• Subject: [edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
  • Author: Ard Biesheuvel
  • Date: June 7, 2018, 10:46 a.m.
  • Patches: 1 / 1
Changeset
ArmVirtPkg/ArmVirt.dsc.inc                                      |   2 +-
MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S         | 164 +++++
MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S             | 161 +++++
MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm           | 165 +++++
MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf |  50 ++
MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c                | 641 ++++++++++++++++++++
6 files changed, 1182 insertions(+), 1 deletion(-)
Git apply log
Switched to a new branch '20180607104645.22278-1-ard.biesheuvel@linaro.org'
Applying: MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Using index info to reconstruct a base tree...
error: patch failed: ArmVirtPkg/ArmVirt.dsc.inc:41
error: ArmVirtPkg/ArmVirt.dsc.inc: patch does not apply
error: Did you hand edit your patch?
It does not apply to blobs recorded in its index.
Patch failed at 0001 MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
The copy of the patch that failed is found in: .git/rebase-apply/patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Failed to apply patch:
[edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
[edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Posted by Ard Biesheuvel, 2 weeks ago
KVM on ARM refuses to decode load/store instructions used to perform
I/O to emulated devices, and instead relies on the exception syndrome
information to describe the operand register, access size, etc.
This is only possible for instructions that have a single input/output
register (as opposed to ones that increment the offset register, or
load/store pair instructions, etc). Otherwise, QEMU crashes with the
following error

  error: kvm run failed Function not implemented
  R00=01010101 R01=00000008 R02=00000048 R03=08000820
  R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8
  R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080
  R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c
  PSR=800001f3 N--- T svc32
  QEMU: Terminated

and KVM produces a warning such as the following in the kernel log

  kvm [17646]: load/store instruction decoding not implemented

The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic
is based on C code, and when LTO is in effect, the MMIO accesses could
be merged with, e.g., manipulations of the loop counter, producing
opcodes that KVM does not support for emulated MMIO.

So let's add a special ArmVirt flavor of this library that implements
that actual load/store operations in assembler, ensuring that the
instructions involved can be emulated by KVM.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmVirtPkg/ArmVirt.dsc.inc                                      |   2 +-
 MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S         | 164 +++++
 MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S             | 161 +++++
 MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm           | 165 +++++
 MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf |  50 ++
 MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c                | 641 ++++++++++++++++++++
 6 files changed, 1182 insertions(+), 1 deletion(-)

diff --git a/ArmVirtPkg/ArmVirt.dsc.inc b/ArmVirtPkg/ArmVirt.dsc.inc
index 766e4f598a07..7464ac70ed1b 100644
--- a/ArmVirtPkg/ArmVirt.dsc.inc
+++ b/ArmVirtPkg/ArmVirt.dsc.inc
@@ -41,7 +41,7 @@ [LibraryClasses.common]
   PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
   PeCoffGetEntryPointLib|MdePkg/Library/BasePeCoffGetEntryPointLib/BasePeCoffGetEntryPointLib.inf
   PeCoffLib|MdePkg/Library/BasePeCoffLib/BasePeCoffLib.inf
-  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
+  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
   UefiDecompressLib|MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.inf
   CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf
 
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
new file mode 100644
index 000000000000..47be68a3e783
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
@@ -0,0 +1,164 @@
+#
+#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
+#
+#  This program and the accompanying materials are licensed and made available
+#  under the terms and conditions of the BSD License which accompanies this
+#  distribution.  The full text of the license may be found at
+#  http://opensource.org/licenses/bsd-license.php
+#
+#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+#
+
+.text
+.align 3
+
+GCC_ASM_EXPORT(MmioRead8Internal)
+GCC_ASM_EXPORT(MmioWrite8Internal)
+GCC_ASM_EXPORT(MmioRead16Internal)
+GCC_ASM_EXPORT(MmioWrite16Internal)
+GCC_ASM_EXPORT(MmioRead32Internal)
+GCC_ASM_EXPORT(MmioWrite32Internal)
+GCC_ASM_EXPORT(MmioRead64Internal)
+GCC_ASM_EXPORT(MmioWrite64Internal)
+
+//
+//  Reads an 8-bit MMIO register.
+//
+//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 8-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead8Internal):
+  ldrb    w0, [x0]
+  dmb     ld
+  ret
+
+//
+//  Writes an 8-bit MMIO register.
+//
+//  Writes the 8-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 8-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite8Internal):
+  dmb     st
+  strb    w1, [x0]
+  ret
+
+//
+//  Reads a 16-bit MMIO register.
+//
+//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 16-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead16Internal):
+  ldrh    w0, [x0]
+  dmb     ld
+  ret
+
+//
+//  Writes a 16-bit MMIO register.
+//
+//  Writes the 16-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 16-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite16Internal):
+  dmb     st
+  strh    w1, [x0]
+  ret
+
+//
+//  Reads a 32-bit MMIO register.
+//
+//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 32-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead32Internal):
+  ldr     w0, [x0]
+  dmb     ld
+  ret
+
+//
+//  Writes a 32-bit MMIO register.
+//
+//  Writes the 32-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 32-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite32Internal):
+  dmb     st
+  str     w1, [x0]
+  ret
+
+//
+//  Reads a 64-bit MMIO register.
+//
+//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 64-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead64Internal):
+  ldr     x0, [x0]
+  dmb     ld
+  ret
+
+//
+//  Writes a 64-bit MMIO register.
+//
+//  Writes the 64-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 64-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite64Internal):
+  dmb     st
+  str     x1, [x0]
+  ret
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
new file mode 100644
index 000000000000..438805ca7c24
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
@@ -0,0 +1,161 @@
+#
+#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
+#
+#  This program and the accompanying materials are licensed and made available
+#  under the terms and conditions of the BSD License which accompanies this
+#  distribution.  The full text of the license may be found at
+#  http://opensource.org/licenses/bsd-license.php
+#
+#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+#
+
+GCC_ASM_EXPORT(MmioRead8Internal)
+GCC_ASM_EXPORT(MmioWrite8Internal)
+GCC_ASM_EXPORT(MmioRead16Internal)
+GCC_ASM_EXPORT(MmioWrite16Internal)
+GCC_ASM_EXPORT(MmioRead32Internal)
+GCC_ASM_EXPORT(MmioWrite32Internal)
+GCC_ASM_EXPORT(MmioRead64Internal)
+GCC_ASM_EXPORT(MmioWrite64Internal)
+
+//
+//  Reads an 8-bit MMIO register.
+//
+//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 8-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead8Internal):
+  ldrb    r0, [r0]
+  dmb
+  bx      lr
+
+//
+//  Writes an 8-bit MMIO register.
+//
+//  Writes the 8-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 8-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite8Internal):
+  dmb     st
+  strb    r1, [r0]
+  bx      lr
+
+//
+//  Reads a 16-bit MMIO register.
+//
+//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 16-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead16Internal):
+  ldrh    r0, [r0]
+  dmb
+  bx      lr
+
+//
+//  Writes a 16-bit MMIO register.
+//
+//  Writes the 16-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 16-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite16Internal):
+  dmb     st
+  strh    r1, [r0]
+  bx      lr
+
+//
+//  Reads a 32-bit MMIO register.
+//
+//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 32-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead32Internal):
+  ldr     r0, [r0]
+  dmb
+  bx      lr
+
+//
+//  Writes a 32-bit MMIO register.
+//
+//  Writes the 32-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 32-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite32Internal):
+  dmb     st
+  str     r1, [r0]
+  bx      lr
+
+//
+//  Reads a 64-bit MMIO register.
+//
+//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
+//  returned. This function must guarantee that all MMIO read and write
+//  operations are serialized.
+//
+//  If 64-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to read.
+//
+//  @return The value read.
+//
+ASM_PFX(MmioRead64Internal):
+  ldrd    r0, r1, [r0]
+  dmb
+  bx      lr
+
+//
+//  Writes a 64-bit MMIO register.
+//
+//  Writes the 64-bit MMIO register specified by Address with the value specified
+//  by Value and returns Value. This function must guarantee that all MMIO read
+//  and write operations are serialized.
+//
+//  If 64-bit MMIO register operations are not supported, then ASSERT().
+//
+//  @param  Address The MMIO register to write.
+//  @param  Value   The value to write to the MMIO register.
+//
+ASM_PFX(MmioWrite64Internal):
+  dmb     st
+  strd    r2, r3, [r0]
+  bx      lr
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
new file mode 100644
index 000000000000..82add82f800a
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
@@ -0,0 +1,165 @@
+;
+;  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
+;
+;  This program and the accompanying materials are licensed and made available
+;  under the terms and conditions of the BSD License which accompanies this
+;  distribution.  The full text of the license may be found at
+;  http:;opensource.org/licenses/bsd-license.php
+;
+;  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+;  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;
+
+
+AREA IoLibMmio, CODE, READONLY
+
+EXPORT MmioRead8Internal
+EXPORT MmioWrite8Internal
+EXPORT MmioRead16Internal
+EXPORT MmioWrite16Internal
+EXPORT MmioRead32Internal
+EXPORT MmioWrite32Internal
+EXPORT MmioRead64Internal
+EXPORT MmioWrite64Internal
+
+;
+;  Reads an 8-bit MMIO register.
+;
+;  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
+;  returned. This function must guarantee that all MMIO read and write
+;  operations are serialized.
+;
+;  If 8-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to read.
+;
+;  @return The value read.
+;
+MmioRead8Internal
+  ldrb    r0, [r0]
+  dmb
+  bx      lr
+
+;
+;  Writes an 8-bit MMIO register.
+;
+;  Writes the 8-bit MMIO register specified by Address with the value specified
+;  by Value and returns Value. This function must guarantee that all MMIO read
+;  and write operations are serialized.
+;
+;  If 8-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to write.
+;  @param  Value   The value to write to the MMIO register.
+;
+MmioWrite8Internal
+  dmb     st
+  strb    r1, [r0]
+  bx      lr
+
+;
+;  Reads a 16-bit MMIO register.
+;
+;  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
+;  returned. This function must guarantee that all MMIO read and write
+;  operations are serialized.
+;
+;  If 16-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to read.
+;
+;  @return The value read.
+;
+MmioRead16Internal
+  ldrh    r0, [r0]
+  dmb
+  bx      lr
+
+;
+;  Writes a 16-bit MMIO register.
+;
+;  Writes the 16-bit MMIO register specified by Address with the value specified
+;  by Value and returns Value. This function must guarantee that all MMIO read
+;  and write operations are serialized.
+;
+;  If 16-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to write.
+;  @param  Value   The value to write to the MMIO register.
+;
+MmioWrite16Internal
+  dmb     st
+  strh    r1, [r0]
+  bx      lr
+
+;
+;  Reads a 32-bit MMIO register.
+;
+;  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
+;  returned. This function must guarantee that all MMIO read and write
+;  operations are serialized.
+;
+;  If 32-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to read.
+;
+;  @return The value read.
+;
+MmioRead32Internal
+  ldr     r0, [r0]
+  dmb
+  bx      lr
+
+;
+;  Writes a 32-bit MMIO register.
+;
+;  Writes the 32-bit MMIO register specified by Address with the value specified
+;  by Value and returns Value. This function must guarantee that all MMIO read
+;  and write operations are serialized.
+;
+;  If 32-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to write.
+;  @param  Value   The value to write to the MMIO register.
+;
+MmioWrite32Internal
+  dmb     st
+  str     r1, [r0]
+  bx      lr
+
+;
+;  Reads a 64-bit MMIO register.
+;
+;  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
+;  returned. This function must guarantee that all MMIO read and write
+;  operations are serialized.
+;
+;  If 64-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to read.
+;
+;  @return The value read.
+;
+MmioRead64Internal
+  ldrd    r0, r1, [r0]
+  dmb
+  bx      lr
+
+;
+;  Writes a 64-bit MMIO register.
+;
+;  Writes the 64-bit MMIO register specified by Address with the value specified
+;  by Value and returns Value. This function must guarantee that all MMIO read
+;  and write operations are serialized.
+;
+;  If 64-bit MMIO register operations are not supported, then ASSERT().
+;
+;  @param  Address The MMIO register to write.
+;  @param  Value   The value to write to the MMIO register.
+;
+MmioWrite64Internal
+  dmb     st
+  strd    r2, r3, [r0]
+  bx      lr
+
+  END
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
new file mode 100644
index 000000000000..5a1dc87ed2bd
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
@@ -0,0 +1,50 @@
+## @file
+#  Instance of I/O Library using KVM/ARM safe assembler routines
+#
+#  Copyright (c) 2007 - 2015, Intel Corporation. All rights reserved.<BR>
+#  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
+#  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
+#  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
+#
+#  This program and the accompanying materials are licensed and made available
+#  under the terms and conditions of the BSD License which accompanies this
+#  distribution. The full text of the license may be found at
+#  http://opensource.org/licenses/bsd-license.php.
+#
+#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x0001001A
+  BASE_NAME                      = BaseIoLibIntrinsicArmVirt
+  FILE_GUID                      = 217102b4-b465-4a1d-a2de-93dd385ec480
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = IoLib
+
+#
+#  VALID_ARCHITECTURES           = ARM AARCH64
+#
+
+[Sources]
+  IoLibMmioBuffer.c
+  BaseIoLibIntrinsicInternal.h
+  IoHighLevel.c
+
+[Sources.ARM]
+  IoLibArmVirt.c
+  Arm/ArmVirtMmio.S   | GCC
+  Arm/ArmVirtMmio.asm | RVCT
+
+[Sources.AARCH64]
+  IoLibArmVirt.c
+  AArch64/ArmVirtMmio.S
+
+[Packages]
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  DebugLib
+  BaseLib
diff --git a/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
new file mode 100644
index 000000000000..154d583246ac
--- /dev/null
+++ b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
@@ -0,0 +1,641 @@
+/** @file
+  I/O Library for ARM.
+
+  Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
+  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
+  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
+  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
+
+  This program and the accompanying materials are licensed and made available
+  under the terms and conditions of the BSD License which accompanies this
+  distribution. The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php.
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include "BaseIoLibIntrinsicInternal.h"
+
+UINT8
+EFIAPI
+MmioRead8Internal (
+  IN      UINTN                     Address
+  );
+
+VOID
+EFIAPI
+MmioWrite8Internal (
+  IN      UINTN                     Address,
+  IN      UINT8                     Value
+  );
+
+UINT16
+EFIAPI
+MmioRead16Internal (
+  IN      UINTN                     Address
+  );
+
+VOID
+EFIAPI
+MmioWrite16Internal (
+  IN      UINTN                     Address,
+  IN      UINT16                    Value
+  );
+
+UINT32
+EFIAPI
+MmioRead32Internal (
+  IN      UINTN                     Address
+  );
+
+VOID
+EFIAPI
+MmioWrite32Internal (
+  IN      UINTN                     Address,
+  IN      UINT32                    Value
+  );
+
+UINT64
+EFIAPI
+MmioRead64Internal (
+  IN      UINTN                     Address
+  );
+
+VOID
+EFIAPI
+MmioWrite64Internal (
+  IN      UINTN                     Address,
+  IN      UINT64                    Value
+  );
+
+/**
+  Reads an 8-bit I/O port.
+
+  Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
+  This function must guarantee that all I/O read and write operations are
+  serialized.
+
+  If 8-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port  The I/O port to read.
+
+  @return The value read.
+
+**/
+UINT8
+EFIAPI
+IoRead8 (
+  IN      UINTN                     Port
+  )
+{
+  ASSERT (FALSE);
+  return 0;
+}
+
+/**
+  Writes an 8-bit I/O port.
+
+  Writes the 8-bit I/O port specified by Port with the value specified by Value
+  and returns Value. This function must guarantee that all I/O read and write
+  operations are serialized.
+
+  If 8-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port  The I/O port to write.
+  @param  Value The value to write to the I/O port.
+
+  @return The value written the I/O port.
+
+**/
+UINT8
+EFIAPI
+IoWrite8 (
+  IN      UINTN                     Port,
+  IN      UINT8                     Value
+  )
+{
+  ASSERT (FALSE);
+  return Value;
+}
+
+/**
+  Reads a 16-bit I/O port.
+
+  Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
+  This function must guarantee that all I/O read and write operations are
+  serialized.
+
+  If 16-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port  The I/O port to read.
+
+  @return The value read.
+
+**/
+UINT16
+EFIAPI
+IoRead16 (
+  IN      UINTN                     Port
+  )
+{
+  ASSERT (FALSE);
+  return 0;
+}
+
+/**
+  Writes a 16-bit I/O port.
+
+  Writes the 16-bit I/O port specified by Port with the value specified by Value
+  and returns Value. This function must guarantee that all I/O read and write
+  operations are serialized.
+
+  If 16-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port  The I/O port to write.
+  @param  Value The value to write to the I/O port.
+
+  @return The value written the I/O port.
+
+**/
+UINT16
+EFIAPI
+IoWrite16 (
+  IN      UINTN                     Port,
+  IN      UINT16                    Value
+  )
+{
+  ASSERT (FALSE);
+  return Value;
+}
+
+/**
+  Reads a 32-bit I/O port.
+
+  Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
+  This function must guarantee that all I/O read and write operations are
+  serialized.
+
+  If 32-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port  The I/O port to read.
+
+  @return The value read.
+
+**/
+UINT32
+EFIAPI
+IoRead32 (
+  IN      UINTN                     Port
+  )
+{
+  ASSERT (FALSE);
+  return 0;
+}
+
+/**
+  Writes a 32-bit I/O port.
+
+  Writes the 32-bit I/O port specified by Port with the value specified by Value
+  and returns Value. This function must guarantee that all I/O read and write
+  operations are serialized.
+
+  If 32-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port  The I/O port to write.
+  @param  Value The value to write to the I/O port.
+
+  @return The value written the I/O port.
+
+**/
+UINT32
+EFIAPI
+IoWrite32 (
+  IN      UINTN                     Port,
+  IN      UINT32                    Value
+  )
+{
+  ASSERT (FALSE);
+  return Value;
+}
+
+/**
+  Reads a 64-bit I/O port.
+
+  Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
+  This function must guarantee that all I/O read and write operations are
+  serialized.
+
+  If 64-bit I/O port operations are not supported, then ASSERT().
+  If Port is not aligned on a 64-bit boundary, then ASSERT().
+
+  @param  Port  The I/O port to read.
+
+  @return The value read.
+
+**/
+UINT64
+EFIAPI
+IoRead64 (
+  IN      UINTN                     Port
+  )
+{
+  ASSERT (FALSE);
+  return 0;
+}
+
+/**
+  Writes a 64-bit I/O port.
+
+  Writes the 64-bit I/O port specified by Port with the value specified by Value
+  and returns Value. This function must guarantee that all I/O read and write
+  operations are serialized.
+
+  If 64-bit I/O port operations are not supported, then ASSERT().
+  If Port is not aligned on a 64-bit boundary, then ASSERT().
+
+  @param  Port  The I/O port to write.
+  @param  Value The value to write to the I/O port.
+
+  @return The value written to the I/O port.
+
+**/
+UINT64
+EFIAPI
+IoWrite64 (
+  IN      UINTN                     Port,
+  IN      UINT64                    Value
+  )
+{
+  ASSERT (FALSE);
+  return 0;
+}
+
+/**
+  Reads an 8-bit I/O port fifo into a block of memory.
+
+  Reads the 8-bit I/O fifo port specified by Port.
+  The port is read Count times, and the read data is
+  stored in the provided Buffer.
+
+  This function must guarantee that all I/O read and write operations are
+  serialized.
+
+  If 8-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port    The I/O port to read.
+  @param  Count   The number of times to read I/O port.
+  @param  Buffer  The buffer to store the read data into.
+
+**/
+VOID
+EFIAPI
+IoReadFifo8 (
+  IN      UINTN                     Port,
+  IN      UINTN                     Count,
+  OUT     VOID                      *Buffer
+  )
+{
+  ASSERT (FALSE);
+}
+
+/**
+  Writes a block of memory into an 8-bit I/O port fifo.
+
+  Writes the 8-bit I/O fifo port specified by Port.
+  The port is written Count times, and the write data is
+  retrieved from the provided Buffer.
+
+  This function must guarantee that all I/O write and write operations are
+  serialized.
+
+  If 8-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port    The I/O port to write.
+  @param  Count   The number of times to write I/O port.
+  @param  Buffer  The buffer to retrieve the write data from.
+
+**/
+VOID
+EFIAPI
+IoWriteFifo8 (
+  IN      UINTN                     Port,
+  IN      UINTN                     Count,
+  IN      VOID                      *Buffer
+  )
+{
+  ASSERT (FALSE);
+}
+
+/**
+  Reads a 16-bit I/O port fifo into a block of memory.
+
+  Reads the 16-bit I/O fifo port specified by Port.
+  The port is read Count times, and the read data is
+  stored in the provided Buffer.
+
+  This function must guarantee that all I/O read and write operations are
+  serialized.
+
+  If 16-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port    The I/O port to read.
+  @param  Count   The number of times to read I/O port.
+  @param  Buffer  The buffer to store the read data into.
+
+**/
+VOID
+EFIAPI
+IoReadFifo16 (
+  IN      UINTN                     Port,
+  IN      UINTN                     Count,
+  OUT     VOID                      *Buffer
+  )
+{
+  ASSERT (FALSE);
+}
+
+/**
+  Writes a block of memory into a 16-bit I/O port fifo.
+
+  Writes the 16-bit I/O fifo port specified by Port.
+  The port is written Count times, and the write data is
+  retrieved from the provided Buffer.
+
+  This function must guarantee that all I/O write and write operations are
+  serialized.
+
+  If 16-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port    The I/O port to write.
+  @param  Count   The number of times to write I/O port.
+  @param  Buffer  The buffer to retrieve the write data from.
+
+**/
+VOID
+EFIAPI
+IoWriteFifo16 (
+  IN      UINTN                     Port,
+  IN      UINTN                     Count,
+  IN      VOID                      *Buffer
+  )
+{
+  ASSERT (FALSE);
+}
+
+/**
+  Reads a 32-bit I/O port fifo into a block of memory.
+
+  Reads the 32-bit I/O fifo port specified by Port.
+  The port is read Count times, and the read data is
+  stored in the provided Buffer.
+
+  This function must guarantee that all I/O read and write operations are
+  serialized.
+
+  If 32-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port    The I/O port to read.
+  @param  Count   The number of times to read I/O port.
+  @param  Buffer  The buffer to store the read data into.
+
+**/
+VOID
+EFIAPI
+IoReadFifo32 (
+  IN      UINTN                     Port,
+  IN      UINTN                     Count,
+  OUT     VOID                      *Buffer
+  )
+{
+  ASSERT (FALSE);
+}
+
+/**
+  Writes a block of memory into a 32-bit I/O port fifo.
+
+  Writes the 32-bit I/O fifo port specified by Port.
+  The port is written Count times, and the write data is
+  retrieved from the provided Buffer.
+
+  This function must guarantee that all I/O write and write operations are
+  serialized.
+
+  If 32-bit I/O port operations are not supported, then ASSERT().
+
+  @param  Port    The I/O port to write.
+  @param  Count   The number of times to write I/O port.
+  @param  Buffer  The buffer to retrieve the write data from.
+
+**/
+VOID
+EFIAPI
+IoWriteFifo32 (
+  IN      UINTN                     Port,
+  IN      UINTN                     Count,
+  IN      VOID                      *Buffer
+  )
+{
+  ASSERT (FALSE);
+}
+
+/**
+  Reads an 8-bit MMIO register.
+
+  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
+  returned. This function must guarantee that all MMIO read and write
+  operations are serialized.
+
+  If 8-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to read.
+
+  @return The value read.
+
+**/
+UINT8
+EFIAPI
+MmioRead8 (
+  IN      UINTN                     Address
+  )
+{
+  return MmioRead8Internal (Address);
+}
+
+/**
+  Writes an 8-bit MMIO register.
+
+  Writes the 8-bit MMIO register specified by Address with the value specified
+  by Value and returns Value. This function must guarantee that all MMIO read
+  and write operations are serialized.
+
+  If 8-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to write.
+  @param  Value   The value to write to the MMIO register.
+
+**/
+UINT8
+EFIAPI
+MmioWrite8 (
+  IN      UINTN                     Address,
+  IN      UINT8                     Value
+  )
+{
+  MmioWrite8Internal (Address, Value);
+  return Value;
+}
+
+/**
+  Reads a 16-bit MMIO register.
+
+  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
+  returned. This function must guarantee that all MMIO read and write
+  operations are serialized.
+
+  If 16-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to read.
+
+  @return The value read.
+
+**/
+UINT16
+EFIAPI
+MmioRead16 (
+  IN      UINTN                     Address
+  )
+{
+  ASSERT ((Address & 1) == 0);
+
+  return MmioRead16Internal (Address);
+}
+
+/**
+  Writes a 16-bit MMIO register.
+
+  Writes the 16-bit MMIO register specified by Address with the value specified
+  by Value and returns Value. This function must guarantee that all MMIO read
+  and write operations are serialized.
+
+  If 16-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to write.
+  @param  Value   The value to write to the MMIO register.
+
+**/
+UINT16
+EFIAPI
+MmioWrite16 (
+  IN      UINTN                     Address,
+  IN      UINT16                    Value
+  )
+{
+  ASSERT ((Address & 1) == 0);
+
+  MmioWrite16Internal (Address, Value);
+  return Value;
+}
+
+/**
+  Reads a 32-bit MMIO register.
+
+  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
+  returned. This function must guarantee that all MMIO read and write
+  operations are serialized.
+
+  If 32-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to read.
+
+  @return The value read.
+
+**/
+UINT32
+EFIAPI
+MmioRead32 (
+  IN      UINTN                     Address
+  )
+{
+  ASSERT ((Address & 3) == 0);
+
+  return MmioRead32Internal (Address);
+}
+
+/**
+  Writes a 32-bit MMIO register.
+
+  Writes the 32-bit MMIO register specified by Address with the value specified
+  by Value and returns Value. This function must guarantee that all MMIO read
+  and write operations are serialized.
+
+  If 32-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to write.
+  @param  Value   The value to write to the MMIO register.
+
+**/
+UINT32
+EFIAPI
+MmioWrite32 (
+  IN      UINTN                     Address,
+  IN      UINT32                    Value
+  )
+{
+  ASSERT ((Address & 3) == 0);
+
+  MmioWrite32Internal (Address, Value);
+  return Value;
+}
+
+/**
+  Reads a 64-bit MMIO register.
+
+  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
+  returned. This function must guarantee that all MMIO read and write
+  operations are serialized.
+
+  If 64-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to read.
+
+  @return The value read.
+
+**/
+UINT64
+EFIAPI
+MmioRead64 (
+  IN      UINTN                     Address
+  )
+{
+  ASSERT ((Address & 7) == 0);
+
+  return MmioRead64Internal (Address);
+}
+
+/**
+  Writes a 64-bit MMIO register.
+
+  Writes the 64-bit MMIO register specified by Address with the value specified
+  by Value and returns Value. This function must guarantee that all MMIO read
+  and write operations are serialized.
+
+  If 64-bit MMIO register operations are not supported, then ASSERT().
+
+  @param  Address The MMIO register to write.
+  @param  Value   The value to write to the MMIO register.
+
+**/
+UINT64
+EFIAPI
+MmioWrite64 (
+  IN      UINTN                     Address,
+  IN      UINT64                    Value
+  )
+{
+  ASSERT ((Address & 7) == 0);
+
+  MmioWrite64Internal (Address, Value);
+  return Value;
+}
-- 
2.17.0

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Re: [edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Posted by Gao, Liming, 2 weeks ago
Ard:
  If this library instance is specific to ARM emulator with KVM, how about add it into ArmVirtPkg?

Thanks
Liming
> -----Original Message-----
> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> Sent: Thursday, June 7, 2018 6:47 PM
> To: edk2-devel@lists.01.org
> Cc: lersek@redhat.com; leif.lindholm@linaro.org; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Subject: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
> 
> KVM on ARM refuses to decode load/store instructions used to perform
> I/O to emulated devices, and instead relies on the exception syndrome
> information to describe the operand register, access size, etc.
> This is only possible for instructions that have a single input/output
> register (as opposed to ones that increment the offset register, or
> load/store pair instructions, etc). Otherwise, QEMU crashes with the
> following error
> 
>   error: kvm run failed Function not implemented
>   R00=01010101 R01=00000008 R02=00000048 R03=08000820
>   R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8
>   R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080
>   R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c
>   PSR=800001f3 N--- T svc32
>   QEMU: Terminated
> 
> and KVM produces a warning such as the following in the kernel log
> 
>   kvm [17646]: load/store instruction decoding not implemented
> 
> The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic
> is based on C code, and when LTO is in effect, the MMIO accesses could
> be merged with, e.g., manipulations of the loop counter, producing
> opcodes that KVM does not support for emulated MMIO.
> 
> So let's add a special ArmVirt flavor of this library that implements
> that actual load/store operations in assembler, ensuring that the
> instructions involved can be emulated by KVM.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  ArmVirtPkg/ArmVirt.dsc.inc                                      |   2 +-
>  MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S         | 164 +++++
>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S             | 161 +++++
>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm           | 165 +++++
>  MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf |  50 ++
>  MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c                | 641 ++++++++++++++++++++
>  6 files changed, 1182 insertions(+), 1 deletion(-)
> 
> diff --git a/ArmVirtPkg/ArmVirt.dsc.inc b/ArmVirtPkg/ArmVirt.dsc.inc
> index 766e4f598a07..7464ac70ed1b 100644
> --- a/ArmVirtPkg/ArmVirt.dsc.inc
> +++ b/ArmVirtPkg/ArmVirt.dsc.inc
> @@ -41,7 +41,7 @@ [LibraryClasses.common]
>    PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
>    PeCoffGetEntryPointLib|MdePkg/Library/BasePeCoffGetEntryPointLib/BasePeCoffGetEntryPointLib.inf
>    PeCoffLib|MdePkg/Library/BasePeCoffLib/BasePeCoffLib.inf
> -  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
> +  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>    UefiDecompressLib|MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.inf
>    CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf
> 
> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
> new file mode 100644
> index 000000000000..47be68a3e783
> --- /dev/null
> +++ b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
> @@ -0,0 +1,164 @@
> +#
> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
> +#
> +#  This program and the accompanying materials are licensed and made available
> +#  under the terms and conditions of the BSD License which accompanies this
> +#  distribution.  The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php
> +#
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +#
> +#
> +
> +.text
> +.align 3
> +
> +GCC_ASM_EXPORT(MmioRead8Internal)
> +GCC_ASM_EXPORT(MmioWrite8Internal)
> +GCC_ASM_EXPORT(MmioRead16Internal)
> +GCC_ASM_EXPORT(MmioWrite16Internal)
> +GCC_ASM_EXPORT(MmioRead32Internal)
> +GCC_ASM_EXPORT(MmioWrite32Internal)
> +GCC_ASM_EXPORT(MmioRead64Internal)
> +GCC_ASM_EXPORT(MmioWrite64Internal)
> +
> +//
> +//  Reads an 8-bit MMIO register.
> +//
> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead8Internal):
> +  ldrb    w0, [x0]
> +  dmb     ld
> +  ret
> +
> +//
> +//  Writes an 8-bit MMIO register.
> +//
> +//  Writes the 8-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite8Internal):
> +  dmb     st
> +  strb    w1, [x0]
> +  ret
> +
> +//
> +//  Reads a 16-bit MMIO register.
> +//
> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead16Internal):
> +  ldrh    w0, [x0]
> +  dmb     ld
> +  ret
> +
> +//
> +//  Writes a 16-bit MMIO register.
> +//
> +//  Writes the 16-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite16Internal):
> +  dmb     st
> +  strh    w1, [x0]
> +  ret
> +
> +//
> +//  Reads a 32-bit MMIO register.
> +//
> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead32Internal):
> +  ldr     w0, [x0]
> +  dmb     ld
> +  ret
> +
> +//
> +//  Writes a 32-bit MMIO register.
> +//
> +//  Writes the 32-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite32Internal):
> +  dmb     st
> +  str     w1, [x0]
> +  ret
> +
> +//
> +//  Reads a 64-bit MMIO register.
> +//
> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead64Internal):
> +  ldr     x0, [x0]
> +  dmb     ld
> +  ret
> +
> +//
> +//  Writes a 64-bit MMIO register.
> +//
> +//  Writes the 64-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite64Internal):
> +  dmb     st
> +  str     x1, [x0]
> +  ret
> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
> new file mode 100644
> index 000000000000..438805ca7c24
> --- /dev/null
> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
> @@ -0,0 +1,161 @@
> +#
> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
> +#
> +#  This program and the accompanying materials are licensed and made available
> +#  under the terms and conditions of the BSD License which accompanies this
> +#  distribution.  The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php
> +#
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +#
> +#
> +
> +GCC_ASM_EXPORT(MmioRead8Internal)
> +GCC_ASM_EXPORT(MmioWrite8Internal)
> +GCC_ASM_EXPORT(MmioRead16Internal)
> +GCC_ASM_EXPORT(MmioWrite16Internal)
> +GCC_ASM_EXPORT(MmioRead32Internal)
> +GCC_ASM_EXPORT(MmioWrite32Internal)
> +GCC_ASM_EXPORT(MmioRead64Internal)
> +GCC_ASM_EXPORT(MmioWrite64Internal)
> +
> +//
> +//  Reads an 8-bit MMIO register.
> +//
> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead8Internal):
> +  ldrb    r0, [r0]
> +  dmb
> +  bx      lr
> +
> +//
> +//  Writes an 8-bit MMIO register.
> +//
> +//  Writes the 8-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite8Internal):
> +  dmb     st
> +  strb    r1, [r0]
> +  bx      lr
> +
> +//
> +//  Reads a 16-bit MMIO register.
> +//
> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead16Internal):
> +  ldrh    r0, [r0]
> +  dmb
> +  bx      lr
> +
> +//
> +//  Writes a 16-bit MMIO register.
> +//
> +//  Writes the 16-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite16Internal):
> +  dmb     st
> +  strh    r1, [r0]
> +  bx      lr
> +
> +//
> +//  Reads a 32-bit MMIO register.
> +//
> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead32Internal):
> +  ldr     r0, [r0]
> +  dmb
> +  bx      lr
> +
> +//
> +//  Writes a 32-bit MMIO register.
> +//
> +//  Writes the 32-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite32Internal):
> +  dmb     st
> +  str     r1, [r0]
> +  bx      lr
> +
> +//
> +//  Reads a 64-bit MMIO register.
> +//
> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> +//  returned. This function must guarantee that all MMIO read and write
> +//  operations are serialized.
> +//
> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to read.
> +//
> +//  @return The value read.
> +//
> +ASM_PFX(MmioRead64Internal):
> +  ldrd    r0, r1, [r0]
> +  dmb
> +  bx      lr
> +
> +//
> +//  Writes a 64-bit MMIO register.
> +//
> +//  Writes the 64-bit MMIO register specified by Address with the value specified
> +//  by Value and returns Value. This function must guarantee that all MMIO read
> +//  and write operations are serialized.
> +//
> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> +//
> +//  @param  Address The MMIO register to write.
> +//  @param  Value   The value to write to the MMIO register.
> +//
> +ASM_PFX(MmioWrite64Internal):
> +  dmb     st
> +  strd    r2, r3, [r0]
> +  bx      lr
> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
> new file mode 100644
> index 000000000000..82add82f800a
> --- /dev/null
> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
> @@ -0,0 +1,165 @@
> +;
> +;  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
> +;
> +;  This program and the accompanying materials are licensed and made available
> +;  under the terms and conditions of the BSD License which accompanies this
> +;  distribution.  The full text of the license may be found at
> +;  http:;opensource.org/licenses/bsd-license.php
> +;
> +;  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +;  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +;
> +
> +
> +AREA IoLibMmio, CODE, READONLY
> +
> +EXPORT MmioRead8Internal
> +EXPORT MmioWrite8Internal
> +EXPORT MmioRead16Internal
> +EXPORT MmioWrite16Internal
> +EXPORT MmioRead32Internal
> +EXPORT MmioWrite32Internal
> +EXPORT MmioRead64Internal
> +EXPORT MmioWrite64Internal
> +
> +;
> +;  Reads an 8-bit MMIO register.
> +;
> +;  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> +;  returned. This function must guarantee that all MMIO read and write
> +;  operations are serialized.
> +;
> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to read.
> +;
> +;  @return The value read.
> +;
> +MmioRead8Internal
> +  ldrb    r0, [r0]
> +  dmb
> +  bx      lr
> +
> +;
> +;  Writes an 8-bit MMIO register.
> +;
> +;  Writes the 8-bit MMIO register specified by Address with the value specified
> +;  by Value and returns Value. This function must guarantee that all MMIO read
> +;  and write operations are serialized.
> +;
> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to write.
> +;  @param  Value   The value to write to the MMIO register.
> +;
> +MmioWrite8Internal
> +  dmb     st
> +  strb    r1, [r0]
> +  bx      lr
> +
> +;
> +;  Reads a 16-bit MMIO register.
> +;
> +;  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> +;  returned. This function must guarantee that all MMIO read and write
> +;  operations are serialized.
> +;
> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to read.
> +;
> +;  @return The value read.
> +;
> +MmioRead16Internal
> +  ldrh    r0, [r0]
> +  dmb
> +  bx      lr
> +
> +;
> +;  Writes a 16-bit MMIO register.
> +;
> +;  Writes the 16-bit MMIO register specified by Address with the value specified
> +;  by Value and returns Value. This function must guarantee that all MMIO read
> +;  and write operations are serialized.
> +;
> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to write.
> +;  @param  Value   The value to write to the MMIO register.
> +;
> +MmioWrite16Internal
> +  dmb     st
> +  strh    r1, [r0]
> +  bx      lr
> +
> +;
> +;  Reads a 32-bit MMIO register.
> +;
> +;  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> +;  returned. This function must guarantee that all MMIO read and write
> +;  operations are serialized.
> +;
> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to read.
> +;
> +;  @return The value read.
> +;
> +MmioRead32Internal
> +  ldr     r0, [r0]
> +  dmb
> +  bx      lr
> +
> +;
> +;  Writes a 32-bit MMIO register.
> +;
> +;  Writes the 32-bit MMIO register specified by Address with the value specified
> +;  by Value and returns Value. This function must guarantee that all MMIO read
> +;  and write operations are serialized.
> +;
> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to write.
> +;  @param  Value   The value to write to the MMIO register.
> +;
> +MmioWrite32Internal
> +  dmb     st
> +  str     r1, [r0]
> +  bx      lr
> +
> +;
> +;  Reads a 64-bit MMIO register.
> +;
> +;  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> +;  returned. This function must guarantee that all MMIO read and write
> +;  operations are serialized.
> +;
> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to read.
> +;
> +;  @return The value read.
> +;
> +MmioRead64Internal
> +  ldrd    r0, r1, [r0]
> +  dmb
> +  bx      lr
> +
> +;
> +;  Writes a 64-bit MMIO register.
> +;
> +;  Writes the 64-bit MMIO register specified by Address with the value specified
> +;  by Value and returns Value. This function must guarantee that all MMIO read
> +;  and write operations are serialized.
> +;
> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
> +;
> +;  @param  Address The MMIO register to write.
> +;  @param  Value   The value to write to the MMIO register.
> +;
> +MmioWrite64Internal
> +  dmb     st
> +  strd    r2, r3, [r0]
> +  bx      lr
> +
> +  END
> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
> b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
> new file mode 100644
> index 000000000000..5a1dc87ed2bd
> --- /dev/null
> +++ b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
> @@ -0,0 +1,50 @@
> +## @file
> +#  Instance of I/O Library using KVM/ARM safe assembler routines
> +#
> +#  Copyright (c) 2007 - 2015, Intel Corporation. All rights reserved.<BR>
> +#  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
> +#  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
> +#  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
> +#
> +#  This program and the accompanying materials are licensed and made available
> +#  under the terms and conditions of the BSD License which accompanies this
> +#  distribution. The full text of the license may be found at
> +#  http://opensource.org/licenses/bsd-license.php.
> +#
> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +#
> +##
> +
> +[Defines]
> +  INF_VERSION                    = 0x0001001A
> +  BASE_NAME                      = BaseIoLibIntrinsicArmVirt
> +  FILE_GUID                      = 217102b4-b465-4a1d-a2de-93dd385ec480
> +  MODULE_TYPE                    = BASE
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = IoLib
> +
> +#
> +#  VALID_ARCHITECTURES           = ARM AARCH64
> +#
> +
> +[Sources]
> +  IoLibMmioBuffer.c
> +  BaseIoLibIntrinsicInternal.h
> +  IoHighLevel.c
> +
> +[Sources.ARM]
> +  IoLibArmVirt.c
> +  Arm/ArmVirtMmio.S   | GCC
> +  Arm/ArmVirtMmio.asm | RVCT
> +
> +[Sources.AARCH64]
> +  IoLibArmVirt.c
> +  AArch64/ArmVirtMmio.S
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +
> +[LibraryClasses]
> +  DebugLib
> +  BaseLib
> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
> new file mode 100644
> index 000000000000..154d583246ac
> --- /dev/null
> +++ b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
> @@ -0,0 +1,641 @@
> +/** @file
> +  I/O Library for ARM.
> +
> +  Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
> +  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
> +  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
> +  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
> +
> +  This program and the accompanying materials are licensed and made available
> +  under the terms and conditions of the BSD License which accompanies this
> +  distribution. The full text of the license may be found at
> +  http://opensource.org/licenses/bsd-license.php.
> +
> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> +  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> +
> +**/
> +
> +#include "BaseIoLibIntrinsicInternal.h"
> +
> +UINT8
> +EFIAPI
> +MmioRead8Internal (
> +  IN      UINTN                     Address
> +  );
> +
> +VOID
> +EFIAPI
> +MmioWrite8Internal (
> +  IN      UINTN                     Address,
> +  IN      UINT8                     Value
> +  );
> +
> +UINT16
> +EFIAPI
> +MmioRead16Internal (
> +  IN      UINTN                     Address
> +  );
> +
> +VOID
> +EFIAPI
> +MmioWrite16Internal (
> +  IN      UINTN                     Address,
> +  IN      UINT16                    Value
> +  );
> +
> +UINT32
> +EFIAPI
> +MmioRead32Internal (
> +  IN      UINTN                     Address
> +  );
> +
> +VOID
> +EFIAPI
> +MmioWrite32Internal (
> +  IN      UINTN                     Address,
> +  IN      UINT32                    Value
> +  );
> +
> +UINT64
> +EFIAPI
> +MmioRead64Internal (
> +  IN      UINTN                     Address
> +  );
> +
> +VOID
> +EFIAPI
> +MmioWrite64Internal (
> +  IN      UINTN                     Address,
> +  IN      UINT64                    Value
> +  );
> +
> +/**
> +  Reads an 8-bit I/O port.
> +
> +  Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
> +  This function must guarantee that all I/O read and write operations are
> +  serialized.
> +
> +  If 8-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port  The I/O port to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT8
> +EFIAPI
> +IoRead8 (
> +  IN      UINTN                     Port
> +  )
> +{
> +  ASSERT (FALSE);
> +  return 0;
> +}
> +
> +/**
> +  Writes an 8-bit I/O port.
> +
> +  Writes the 8-bit I/O port specified by Port with the value specified by Value
> +  and returns Value. This function must guarantee that all I/O read and write
> +  operations are serialized.
> +
> +  If 8-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port  The I/O port to write.
> +  @param  Value The value to write to the I/O port.
> +
> +  @return The value written the I/O port.
> +
> +**/
> +UINT8
> +EFIAPI
> +IoWrite8 (
> +  IN      UINTN                     Port,
> +  IN      UINT8                     Value
> +  )
> +{
> +  ASSERT (FALSE);
> +  return Value;
> +}
> +
> +/**
> +  Reads a 16-bit I/O port.
> +
> +  Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
> +  This function must guarantee that all I/O read and write operations are
> +  serialized.
> +
> +  If 16-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port  The I/O port to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT16
> +EFIAPI
> +IoRead16 (
> +  IN      UINTN                     Port
> +  )
> +{
> +  ASSERT (FALSE);
> +  return 0;
> +}
> +
> +/**
> +  Writes a 16-bit I/O port.
> +
> +  Writes the 16-bit I/O port specified by Port with the value specified by Value
> +  and returns Value. This function must guarantee that all I/O read and write
> +  operations are serialized.
> +
> +  If 16-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port  The I/O port to write.
> +  @param  Value The value to write to the I/O port.
> +
> +  @return The value written the I/O port.
> +
> +**/
> +UINT16
> +EFIAPI
> +IoWrite16 (
> +  IN      UINTN                     Port,
> +  IN      UINT16                    Value
> +  )
> +{
> +  ASSERT (FALSE);
> +  return Value;
> +}
> +
> +/**
> +  Reads a 32-bit I/O port.
> +
> +  Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
> +  This function must guarantee that all I/O read and write operations are
> +  serialized.
> +
> +  If 32-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port  The I/O port to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT32
> +EFIAPI
> +IoRead32 (
> +  IN      UINTN                     Port
> +  )
> +{
> +  ASSERT (FALSE);
> +  return 0;
> +}
> +
> +/**
> +  Writes a 32-bit I/O port.
> +
> +  Writes the 32-bit I/O port specified by Port with the value specified by Value
> +  and returns Value. This function must guarantee that all I/O read and write
> +  operations are serialized.
> +
> +  If 32-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port  The I/O port to write.
> +  @param  Value The value to write to the I/O port.
> +
> +  @return The value written the I/O port.
> +
> +**/
> +UINT32
> +EFIAPI
> +IoWrite32 (
> +  IN      UINTN                     Port,
> +  IN      UINT32                    Value
> +  )
> +{
> +  ASSERT (FALSE);
> +  return Value;
> +}
> +
> +/**
> +  Reads a 64-bit I/O port.
> +
> +  Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
> +  This function must guarantee that all I/O read and write operations are
> +  serialized.
> +
> +  If 64-bit I/O port operations are not supported, then ASSERT().
> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
> +
> +  @param  Port  The I/O port to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT64
> +EFIAPI
> +IoRead64 (
> +  IN      UINTN                     Port
> +  )
> +{
> +  ASSERT (FALSE);
> +  return 0;
> +}
> +
> +/**
> +  Writes a 64-bit I/O port.
> +
> +  Writes the 64-bit I/O port specified by Port with the value specified by Value
> +  and returns Value. This function must guarantee that all I/O read and write
> +  operations are serialized.
> +
> +  If 64-bit I/O port operations are not supported, then ASSERT().
> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
> +
> +  @param  Port  The I/O port to write.
> +  @param  Value The value to write to the I/O port.
> +
> +  @return The value written to the I/O port.
> +
> +**/
> +UINT64
> +EFIAPI
> +IoWrite64 (
> +  IN      UINTN                     Port,
> +  IN      UINT64                    Value
> +  )
> +{
> +  ASSERT (FALSE);
> +  return 0;
> +}
> +
> +/**
> +  Reads an 8-bit I/O port fifo into a block of memory.
> +
> +  Reads the 8-bit I/O fifo port specified by Port.
> +  The port is read Count times, and the read data is
> +  stored in the provided Buffer.
> +
> +  This function must guarantee that all I/O read and write operations are
> +  serialized.
> +
> +  If 8-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port    The I/O port to read.
> +  @param  Count   The number of times to read I/O port.
> +  @param  Buffer  The buffer to store the read data into.
> +
> +**/
> +VOID
> +EFIAPI
> +IoReadFifo8 (
> +  IN      UINTN                     Port,
> +  IN      UINTN                     Count,
> +  OUT     VOID                      *Buffer
> +  )
> +{
> +  ASSERT (FALSE);
> +}
> +
> +/**
> +  Writes a block of memory into an 8-bit I/O port fifo.
> +
> +  Writes the 8-bit I/O fifo port specified by Port.
> +  The port is written Count times, and the write data is
> +  retrieved from the provided Buffer.
> +
> +  This function must guarantee that all I/O write and write operations are
> +  serialized.
> +
> +  If 8-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port    The I/O port to write.
> +  @param  Count   The number of times to write I/O port.
> +  @param  Buffer  The buffer to retrieve the write data from.
> +
> +**/
> +VOID
> +EFIAPI
> +IoWriteFifo8 (
> +  IN      UINTN                     Port,
> +  IN      UINTN                     Count,
> +  IN      VOID                      *Buffer
> +  )
> +{
> +  ASSERT (FALSE);
> +}
> +
> +/**
> +  Reads a 16-bit I/O port fifo into a block of memory.
> +
> +  Reads the 16-bit I/O fifo port specified by Port.
> +  The port is read Count times, and the read data is
> +  stored in the provided Buffer.
> +
> +  This function must guarantee that all I/O read and write operations are
> +  serialized.
> +
> +  If 16-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port    The I/O port to read.
> +  @param  Count   The number of times to read I/O port.
> +  @param  Buffer  The buffer to store the read data into.
> +
> +**/
> +VOID
> +EFIAPI
> +IoReadFifo16 (
> +  IN      UINTN                     Port,
> +  IN      UINTN                     Count,
> +  OUT     VOID                      *Buffer
> +  )
> +{
> +  ASSERT (FALSE);
> +}
> +
> +/**
> +  Writes a block of memory into a 16-bit I/O port fifo.
> +
> +  Writes the 16-bit I/O fifo port specified by Port.
> +  The port is written Count times, and the write data is
> +  retrieved from the provided Buffer.
> +
> +  This function must guarantee that all I/O write and write operations are
> +  serialized.
> +
> +  If 16-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port    The I/O port to write.
> +  @param  Count   The number of times to write I/O port.
> +  @param  Buffer  The buffer to retrieve the write data from.
> +
> +**/
> +VOID
> +EFIAPI
> +IoWriteFifo16 (
> +  IN      UINTN                     Port,
> +  IN      UINTN                     Count,
> +  IN      VOID                      *Buffer
> +  )
> +{
> +  ASSERT (FALSE);
> +}
> +
> +/**
> +  Reads a 32-bit I/O port fifo into a block of memory.
> +
> +  Reads the 32-bit I/O fifo port specified by Port.
> +  The port is read Count times, and the read data is
> +  stored in the provided Buffer.
> +
> +  This function must guarantee that all I/O read and write operations are
> +  serialized.
> +
> +  If 32-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port    The I/O port to read.
> +  @param  Count   The number of times to read I/O port.
> +  @param  Buffer  The buffer to store the read data into.
> +
> +**/
> +VOID
> +EFIAPI
> +IoReadFifo32 (
> +  IN      UINTN                     Port,
> +  IN      UINTN                     Count,
> +  OUT     VOID                      *Buffer
> +  )
> +{
> +  ASSERT (FALSE);
> +}
> +
> +/**
> +  Writes a block of memory into a 32-bit I/O port fifo.
> +
> +  Writes the 32-bit I/O fifo port specified by Port.
> +  The port is written Count times, and the write data is
> +  retrieved from the provided Buffer.
> +
> +  This function must guarantee that all I/O write and write operations are
> +  serialized.
> +
> +  If 32-bit I/O port operations are not supported, then ASSERT().
> +
> +  @param  Port    The I/O port to write.
> +  @param  Count   The number of times to write I/O port.
> +  @param  Buffer  The buffer to retrieve the write data from.
> +
> +**/
> +VOID
> +EFIAPI
> +IoWriteFifo32 (
> +  IN      UINTN                     Port,
> +  IN      UINTN                     Count,
> +  IN      VOID                      *Buffer
> +  )
> +{
> +  ASSERT (FALSE);
> +}
> +
> +/**
> +  Reads an 8-bit MMIO register.
> +
> +  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> +  returned. This function must guarantee that all MMIO read and write
> +  operations are serialized.
> +
> +  If 8-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT8
> +EFIAPI
> +MmioRead8 (
> +  IN      UINTN                     Address
> +  )
> +{
> +  return MmioRead8Internal (Address);
> +}
> +
> +/**
> +  Writes an 8-bit MMIO register.
> +
> +  Writes the 8-bit MMIO register specified by Address with the value specified
> +  by Value and returns Value. This function must guarantee that all MMIO read
> +  and write operations are serialized.
> +
> +  If 8-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to write.
> +  @param  Value   The value to write to the MMIO register.
> +
> +**/
> +UINT8
> +EFIAPI
> +MmioWrite8 (
> +  IN      UINTN                     Address,
> +  IN      UINT8                     Value
> +  )
> +{
> +  MmioWrite8Internal (Address, Value);
> +  return Value;
> +}
> +
> +/**
> +  Reads a 16-bit MMIO register.
> +
> +  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> +  returned. This function must guarantee that all MMIO read and write
> +  operations are serialized.
> +
> +  If 16-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT16
> +EFIAPI
> +MmioRead16 (
> +  IN      UINTN                     Address
> +  )
> +{
> +  ASSERT ((Address & 1) == 0);
> +
> +  return MmioRead16Internal (Address);
> +}
> +
> +/**
> +  Writes a 16-bit MMIO register.
> +
> +  Writes the 16-bit MMIO register specified by Address with the value specified
> +  by Value and returns Value. This function must guarantee that all MMIO read
> +  and write operations are serialized.
> +
> +  If 16-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to write.
> +  @param  Value   The value to write to the MMIO register.
> +
> +**/
> +UINT16
> +EFIAPI
> +MmioWrite16 (
> +  IN      UINTN                     Address,
> +  IN      UINT16                    Value
> +  )
> +{
> +  ASSERT ((Address & 1) == 0);
> +
> +  MmioWrite16Internal (Address, Value);
> +  return Value;
> +}
> +
> +/**
> +  Reads a 32-bit MMIO register.
> +
> +  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> +  returned. This function must guarantee that all MMIO read and write
> +  operations are serialized.
> +
> +  If 32-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT32
> +EFIAPI
> +MmioRead32 (
> +  IN      UINTN                     Address
> +  )
> +{
> +  ASSERT ((Address & 3) == 0);
> +
> +  return MmioRead32Internal (Address);
> +}
> +
> +/**
> +  Writes a 32-bit MMIO register.
> +
> +  Writes the 32-bit MMIO register specified by Address with the value specified
> +  by Value and returns Value. This function must guarantee that all MMIO read
> +  and write operations are serialized.
> +
> +  If 32-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to write.
> +  @param  Value   The value to write to the MMIO register.
> +
> +**/
> +UINT32
> +EFIAPI
> +MmioWrite32 (
> +  IN      UINTN                     Address,
> +  IN      UINT32                    Value
> +  )
> +{
> +  ASSERT ((Address & 3) == 0);
> +
> +  MmioWrite32Internal (Address, Value);
> +  return Value;
> +}
> +
> +/**
> +  Reads a 64-bit MMIO register.
> +
> +  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> +  returned. This function must guarantee that all MMIO read and write
> +  operations are serialized.
> +
> +  If 64-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to read.
> +
> +  @return The value read.
> +
> +**/
> +UINT64
> +EFIAPI
> +MmioRead64 (
> +  IN      UINTN                     Address
> +  )
> +{
> +  ASSERT ((Address & 7) == 0);
> +
> +  return MmioRead64Internal (Address);
> +}
> +
> +/**
> +  Writes a 64-bit MMIO register.
> +
> +  Writes the 64-bit MMIO register specified by Address with the value specified
> +  by Value and returns Value. This function must guarantee that all MMIO read
> +  and write operations are serialized.
> +
> +  If 64-bit MMIO register operations are not supported, then ASSERT().
> +
> +  @param  Address The MMIO register to write.
> +  @param  Value   The value to write to the MMIO register.
> +
> +**/
> +UINT64
> +EFIAPI
> +MmioWrite64 (
> +  IN      UINTN                     Address,
> +  IN      UINT64                    Value
> +  )
> +{
> +  ASSERT ((Address & 7) == 0);
> +
> +  MmioWrite64Internal (Address, Value);
> +  return Value;
> +}
> --
> 2.17.0

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Re: [edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Posted by Ard Biesheuvel, 2 weeks ago
On 7 June 2018 at 17:08, Gao, Liming <liming.gao@intel.com> wrote:
> Ard:
>   If this library instance is specific to ARM emulator with KVM, how about add it into ArmVirtPkg?
>

Laszlo, do you want to take this question?


>> -----Original Message-----
>> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>> Sent: Thursday, June 7, 2018 6:47 PM
>> To: edk2-devel@lists.01.org
>> Cc: lersek@redhat.com; leif.lindholm@linaro.org; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
>> <michael.d.kinney@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> Subject: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
>>
>> KVM on ARM refuses to decode load/store instructions used to perform
>> I/O to emulated devices, and instead relies on the exception syndrome
>> information to describe the operand register, access size, etc.
>> This is only possible for instructions that have a single input/output
>> register (as opposed to ones that increment the offset register, or
>> load/store pair instructions, etc). Otherwise, QEMU crashes with the
>> following error
>>
>>   error: kvm run failed Function not implemented
>>   R00=01010101 R01=00000008 R02=00000048 R03=08000820
>>   R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8
>>   R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080
>>   R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c
>>   PSR=800001f3 N--- T svc32
>>   QEMU: Terminated
>>
>> and KVM produces a warning such as the following in the kernel log
>>
>>   kvm [17646]: load/store instruction decoding not implemented
>>
>> The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic
>> is based on C code, and when LTO is in effect, the MMIO accesses could
>> be merged with, e.g., manipulations of the loop counter, producing
>> opcodes that KVM does not support for emulated MMIO.
>>
>> So let's add a special ArmVirt flavor of this library that implements
>> that actual load/store operations in assembler, ensuring that the
>> instructions involved can be emulated by KVM.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>>  ArmVirtPkg/ArmVirt.dsc.inc                                      |   2 +-
>>  MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S         | 164 +++++
>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S             | 161 +++++
>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm           | 165 +++++
>>  MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf |  50 ++
>>  MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c                | 641 ++++++++++++++++++++
>>  6 files changed, 1182 insertions(+), 1 deletion(-)
>>
>> diff --git a/ArmVirtPkg/ArmVirt.dsc.inc b/ArmVirtPkg/ArmVirt.dsc.inc
>> index 766e4f598a07..7464ac70ed1b 100644
>> --- a/ArmVirtPkg/ArmVirt.dsc.inc
>> +++ b/ArmVirtPkg/ArmVirt.dsc.inc
>> @@ -41,7 +41,7 @@ [LibraryClasses.common]
>>    PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
>>    PeCoffGetEntryPointLib|MdePkg/Library/BasePeCoffGetEntryPointLib/BasePeCoffGetEntryPointLib.inf
>>    PeCoffLib|MdePkg/Library/BasePeCoffLib/BasePeCoffLib.inf
>> -  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>> +  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>>    UefiDecompressLib|MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.inf
>>    CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf
>>
>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
>> new file mode 100644
>> index 000000000000..47be68a3e783
>> --- /dev/null
>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
>> @@ -0,0 +1,164 @@
>> +#
>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>> +#
>> +#  This program and the accompanying materials are licensed and made available
>> +#  under the terms and conditions of the BSD License which accompanies this
>> +#  distribution.  The full text of the license may be found at
>> +#  http://opensource.org/licenses/bsd-license.php
>> +#
>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +#
>> +#
>> +
>> +.text
>> +.align 3
>> +
>> +GCC_ASM_EXPORT(MmioRead8Internal)
>> +GCC_ASM_EXPORT(MmioWrite8Internal)
>> +GCC_ASM_EXPORT(MmioRead16Internal)
>> +GCC_ASM_EXPORT(MmioWrite16Internal)
>> +GCC_ASM_EXPORT(MmioRead32Internal)
>> +GCC_ASM_EXPORT(MmioWrite32Internal)
>> +GCC_ASM_EXPORT(MmioRead64Internal)
>> +GCC_ASM_EXPORT(MmioWrite64Internal)
>> +
>> +//
>> +//  Reads an 8-bit MMIO register.
>> +//
>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead8Internal):
>> +  ldrb    w0, [x0]
>> +  dmb     ld
>> +  ret
>> +
>> +//
>> +//  Writes an 8-bit MMIO register.
>> +//
>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite8Internal):
>> +  dmb     st
>> +  strb    w1, [x0]
>> +  ret
>> +
>> +//
>> +//  Reads a 16-bit MMIO register.
>> +//
>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead16Internal):
>> +  ldrh    w0, [x0]
>> +  dmb     ld
>> +  ret
>> +
>> +//
>> +//  Writes a 16-bit MMIO register.
>> +//
>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite16Internal):
>> +  dmb     st
>> +  strh    w1, [x0]
>> +  ret
>> +
>> +//
>> +//  Reads a 32-bit MMIO register.
>> +//
>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead32Internal):
>> +  ldr     w0, [x0]
>> +  dmb     ld
>> +  ret
>> +
>> +//
>> +//  Writes a 32-bit MMIO register.
>> +//
>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite32Internal):
>> +  dmb     st
>> +  str     w1, [x0]
>> +  ret
>> +
>> +//
>> +//  Reads a 64-bit MMIO register.
>> +//
>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead64Internal):
>> +  ldr     x0, [x0]
>> +  dmb     ld
>> +  ret
>> +
>> +//
>> +//  Writes a 64-bit MMIO register.
>> +//
>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite64Internal):
>> +  dmb     st
>> +  str     x1, [x0]
>> +  ret
>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
>> new file mode 100644
>> index 000000000000..438805ca7c24
>> --- /dev/null
>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
>> @@ -0,0 +1,161 @@
>> +#
>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>> +#
>> +#  This program and the accompanying materials are licensed and made available
>> +#  under the terms and conditions of the BSD License which accompanies this
>> +#  distribution.  The full text of the license may be found at
>> +#  http://opensource.org/licenses/bsd-license.php
>> +#
>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +#
>> +#
>> +
>> +GCC_ASM_EXPORT(MmioRead8Internal)
>> +GCC_ASM_EXPORT(MmioWrite8Internal)
>> +GCC_ASM_EXPORT(MmioRead16Internal)
>> +GCC_ASM_EXPORT(MmioWrite16Internal)
>> +GCC_ASM_EXPORT(MmioRead32Internal)
>> +GCC_ASM_EXPORT(MmioWrite32Internal)
>> +GCC_ASM_EXPORT(MmioRead64Internal)
>> +GCC_ASM_EXPORT(MmioWrite64Internal)
>> +
>> +//
>> +//  Reads an 8-bit MMIO register.
>> +//
>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead8Internal):
>> +  ldrb    r0, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +//
>> +//  Writes an 8-bit MMIO register.
>> +//
>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite8Internal):
>> +  dmb     st
>> +  strb    r1, [r0]
>> +  bx      lr
>> +
>> +//
>> +//  Reads a 16-bit MMIO register.
>> +//
>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead16Internal):
>> +  ldrh    r0, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +//
>> +//  Writes a 16-bit MMIO register.
>> +//
>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite16Internal):
>> +  dmb     st
>> +  strh    r1, [r0]
>> +  bx      lr
>> +
>> +//
>> +//  Reads a 32-bit MMIO register.
>> +//
>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead32Internal):
>> +  ldr     r0, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +//
>> +//  Writes a 32-bit MMIO register.
>> +//
>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite32Internal):
>> +  dmb     st
>> +  str     r1, [r0]
>> +  bx      lr
>> +
>> +//
>> +//  Reads a 64-bit MMIO register.
>> +//
>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> +//  returned. This function must guarantee that all MMIO read and write
>> +//  operations are serialized.
>> +//
>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to read.
>> +//
>> +//  @return The value read.
>> +//
>> +ASM_PFX(MmioRead64Internal):
>> +  ldrd    r0, r1, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +//
>> +//  Writes a 64-bit MMIO register.
>> +//
>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> +//  and write operations are serialized.
>> +//
>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +//
>> +//  @param  Address The MMIO register to write.
>> +//  @param  Value   The value to write to the MMIO register.
>> +//
>> +ASM_PFX(MmioWrite64Internal):
>> +  dmb     st
>> +  strd    r2, r3, [r0]
>> +  bx      lr
>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
>> new file mode 100644
>> index 000000000000..82add82f800a
>> --- /dev/null
>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
>> @@ -0,0 +1,165 @@
>> +;
>> +;  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>> +;
>> +;  This program and the accompanying materials are licensed and made available
>> +;  under the terms and conditions of the BSD License which accompanies this
>> +;  distribution.  The full text of the license may be found at
>> +;  http:;opensource.org/licenses/bsd-license.php
>> +;
>> +;  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +;  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +;
>> +
>> +
>> +AREA IoLibMmio, CODE, READONLY
>> +
>> +EXPORT MmioRead8Internal
>> +EXPORT MmioWrite8Internal
>> +EXPORT MmioRead16Internal
>> +EXPORT MmioWrite16Internal
>> +EXPORT MmioRead32Internal
>> +EXPORT MmioWrite32Internal
>> +EXPORT MmioRead64Internal
>> +EXPORT MmioWrite64Internal
>> +
>> +;
>> +;  Reads an 8-bit MMIO register.
>> +;
>> +;  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> +;  returned. This function must guarantee that all MMIO read and write
>> +;  operations are serialized.
>> +;
>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to read.
>> +;
>> +;  @return The value read.
>> +;
>> +MmioRead8Internal
>> +  ldrb    r0, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +;
>> +;  Writes an 8-bit MMIO register.
>> +;
>> +;  Writes the 8-bit MMIO register specified by Address with the value specified
>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> +;  and write operations are serialized.
>> +;
>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to write.
>> +;  @param  Value   The value to write to the MMIO register.
>> +;
>> +MmioWrite8Internal
>> +  dmb     st
>> +  strb    r1, [r0]
>> +  bx      lr
>> +
>> +;
>> +;  Reads a 16-bit MMIO register.
>> +;
>> +;  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> +;  returned. This function must guarantee that all MMIO read and write
>> +;  operations are serialized.
>> +;
>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to read.
>> +;
>> +;  @return The value read.
>> +;
>> +MmioRead16Internal
>> +  ldrh    r0, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +;
>> +;  Writes a 16-bit MMIO register.
>> +;
>> +;  Writes the 16-bit MMIO register specified by Address with the value specified
>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> +;  and write operations are serialized.
>> +;
>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to write.
>> +;  @param  Value   The value to write to the MMIO register.
>> +;
>> +MmioWrite16Internal
>> +  dmb     st
>> +  strh    r1, [r0]
>> +  bx      lr
>> +
>> +;
>> +;  Reads a 32-bit MMIO register.
>> +;
>> +;  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> +;  returned. This function must guarantee that all MMIO read and write
>> +;  operations are serialized.
>> +;
>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to read.
>> +;
>> +;  @return The value read.
>> +;
>> +MmioRead32Internal
>> +  ldr     r0, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +;
>> +;  Writes a 32-bit MMIO register.
>> +;
>> +;  Writes the 32-bit MMIO register specified by Address with the value specified
>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> +;  and write operations are serialized.
>> +;
>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to write.
>> +;  @param  Value   The value to write to the MMIO register.
>> +;
>> +MmioWrite32Internal
>> +  dmb     st
>> +  str     r1, [r0]
>> +  bx      lr
>> +
>> +;
>> +;  Reads a 64-bit MMIO register.
>> +;
>> +;  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> +;  returned. This function must guarantee that all MMIO read and write
>> +;  operations are serialized.
>> +;
>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to read.
>> +;
>> +;  @return The value read.
>> +;
>> +MmioRead64Internal
>> +  ldrd    r0, r1, [r0]
>> +  dmb
>> +  bx      lr
>> +
>> +;
>> +;  Writes a 64-bit MMIO register.
>> +;
>> +;  Writes the 64-bit MMIO register specified by Address with the value specified
>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> +;  and write operations are serialized.
>> +;
>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +;
>> +;  @param  Address The MMIO register to write.
>> +;  @param  Value   The value to write to the MMIO register.
>> +;
>> +MmioWrite64Internal
>> +  dmb     st
>> +  strd    r2, r3, [r0]
>> +  bx      lr
>> +
>> +  END
>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>> b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>> new file mode 100644
>> index 000000000000..5a1dc87ed2bd
>> --- /dev/null
>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>> @@ -0,0 +1,50 @@
>> +## @file
>> +#  Instance of I/O Library using KVM/ARM safe assembler routines
>> +#
>> +#  Copyright (c) 2007 - 2015, Intel Corporation. All rights reserved.<BR>
>> +#  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
>> +#  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>> +#  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
>> +#
>> +#  This program and the accompanying materials are licensed and made available
>> +#  under the terms and conditions of the BSD License which accompanies this
>> +#  distribution. The full text of the license may be found at
>> +#  http://opensource.org/licenses/bsd-license.php.
>> +#
>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +#
>> +##
>> +
>> +[Defines]
>> +  INF_VERSION                    = 0x0001001A
>> +  BASE_NAME                      = BaseIoLibIntrinsicArmVirt
>> +  FILE_GUID                      = 217102b4-b465-4a1d-a2de-93dd385ec480
>> +  MODULE_TYPE                    = BASE
>> +  VERSION_STRING                 = 1.0
>> +  LIBRARY_CLASS                  = IoLib
>> +
>> +#
>> +#  VALID_ARCHITECTURES           = ARM AARCH64
>> +#
>> +
>> +[Sources]
>> +  IoLibMmioBuffer.c
>> +  BaseIoLibIntrinsicInternal.h
>> +  IoHighLevel.c
>> +
>> +[Sources.ARM]
>> +  IoLibArmVirt.c
>> +  Arm/ArmVirtMmio.S   | GCC
>> +  Arm/ArmVirtMmio.asm | RVCT
>> +
>> +[Sources.AARCH64]
>> +  IoLibArmVirt.c
>> +  AArch64/ArmVirtMmio.S
>> +
>> +[Packages]
>> +  MdePkg/MdePkg.dec
>> +
>> +[LibraryClasses]
>> +  DebugLib
>> +  BaseLib
>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
>> new file mode 100644
>> index 000000000000..154d583246ac
>> --- /dev/null
>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
>> @@ -0,0 +1,641 @@
>> +/** @file
>> +  I/O Library for ARM.
>> +
>> +  Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
>> +  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
>> +  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>> +  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
>> +
>> +  This program and the accompanying materials are licensed and made available
>> +  under the terms and conditions of the BSD License which accompanies this
>> +  distribution. The full text of the license may be found at
>> +  http://opensource.org/licenses/bsd-license.php.
>> +
>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> +  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> +
>> +**/
>> +
>> +#include "BaseIoLibIntrinsicInternal.h"
>> +
>> +UINT8
>> +EFIAPI
>> +MmioRead8Internal (
>> +  IN      UINTN                     Address
>> +  );
>> +
>> +VOID
>> +EFIAPI
>> +MmioWrite8Internal (
>> +  IN      UINTN                     Address,
>> +  IN      UINT8                     Value
>> +  );
>> +
>> +UINT16
>> +EFIAPI
>> +MmioRead16Internal (
>> +  IN      UINTN                     Address
>> +  );
>> +
>> +VOID
>> +EFIAPI
>> +MmioWrite16Internal (
>> +  IN      UINTN                     Address,
>> +  IN      UINT16                    Value
>> +  );
>> +
>> +UINT32
>> +EFIAPI
>> +MmioRead32Internal (
>> +  IN      UINTN                     Address
>> +  );
>> +
>> +VOID
>> +EFIAPI
>> +MmioWrite32Internal (
>> +  IN      UINTN                     Address,
>> +  IN      UINT32                    Value
>> +  );
>> +
>> +UINT64
>> +EFIAPI
>> +MmioRead64Internal (
>> +  IN      UINTN                     Address
>> +  );
>> +
>> +VOID
>> +EFIAPI
>> +MmioWrite64Internal (
>> +  IN      UINTN                     Address,
>> +  IN      UINT64                    Value
>> +  );
>> +
>> +/**
>> +  Reads an 8-bit I/O port.
>> +
>> +  Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
>> +  This function must guarantee that all I/O read and write operations are
>> +  serialized.
>> +
>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port  The I/O port to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT8
>> +EFIAPI
>> +IoRead8 (
>> +  IN      UINTN                     Port
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return 0;
>> +}
>> +
>> +/**
>> +  Writes an 8-bit I/O port.
>> +
>> +  Writes the 8-bit I/O port specified by Port with the value specified by Value
>> +  and returns Value. This function must guarantee that all I/O read and write
>> +  operations are serialized.
>> +
>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port  The I/O port to write.
>> +  @param  Value The value to write to the I/O port.
>> +
>> +  @return The value written the I/O port.
>> +
>> +**/
>> +UINT8
>> +EFIAPI
>> +IoWrite8 (
>> +  IN      UINTN                     Port,
>> +  IN      UINT8                     Value
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return Value;
>> +}
>> +
>> +/**
>> +  Reads a 16-bit I/O port.
>> +
>> +  Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
>> +  This function must guarantee that all I/O read and write operations are
>> +  serialized.
>> +
>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port  The I/O port to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT16
>> +EFIAPI
>> +IoRead16 (
>> +  IN      UINTN                     Port
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return 0;
>> +}
>> +
>> +/**
>> +  Writes a 16-bit I/O port.
>> +
>> +  Writes the 16-bit I/O port specified by Port with the value specified by Value
>> +  and returns Value. This function must guarantee that all I/O read and write
>> +  operations are serialized.
>> +
>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port  The I/O port to write.
>> +  @param  Value The value to write to the I/O port.
>> +
>> +  @return The value written the I/O port.
>> +
>> +**/
>> +UINT16
>> +EFIAPI
>> +IoWrite16 (
>> +  IN      UINTN                     Port,
>> +  IN      UINT16                    Value
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return Value;
>> +}
>> +
>> +/**
>> +  Reads a 32-bit I/O port.
>> +
>> +  Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
>> +  This function must guarantee that all I/O read and write operations are
>> +  serialized.
>> +
>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port  The I/O port to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT32
>> +EFIAPI
>> +IoRead32 (
>> +  IN      UINTN                     Port
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return 0;
>> +}
>> +
>> +/**
>> +  Writes a 32-bit I/O port.
>> +
>> +  Writes the 32-bit I/O port specified by Port with the value specified by Value
>> +  and returns Value. This function must guarantee that all I/O read and write
>> +  operations are serialized.
>> +
>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port  The I/O port to write.
>> +  @param  Value The value to write to the I/O port.
>> +
>> +  @return The value written the I/O port.
>> +
>> +**/
>> +UINT32
>> +EFIAPI
>> +IoWrite32 (
>> +  IN      UINTN                     Port,
>> +  IN      UINT32                    Value
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return Value;
>> +}
>> +
>> +/**
>> +  Reads a 64-bit I/O port.
>> +
>> +  Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
>> +  This function must guarantee that all I/O read and write operations are
>> +  serialized.
>> +
>> +  If 64-bit I/O port operations are not supported, then ASSERT().
>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
>> +
>> +  @param  Port  The I/O port to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT64
>> +EFIAPI
>> +IoRead64 (
>> +  IN      UINTN                     Port
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return 0;
>> +}
>> +
>> +/**
>> +  Writes a 64-bit I/O port.
>> +
>> +  Writes the 64-bit I/O port specified by Port with the value specified by Value
>> +  and returns Value. This function must guarantee that all I/O read and write
>> +  operations are serialized.
>> +
>> +  If 64-bit I/O port operations are not supported, then ASSERT().
>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
>> +
>> +  @param  Port  The I/O port to write.
>> +  @param  Value The value to write to the I/O port.
>> +
>> +  @return The value written to the I/O port.
>> +
>> +**/
>> +UINT64
>> +EFIAPI
>> +IoWrite64 (
>> +  IN      UINTN                     Port,
>> +  IN      UINT64                    Value
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +  return 0;
>> +}
>> +
>> +/**
>> +  Reads an 8-bit I/O port fifo into a block of memory.
>> +
>> +  Reads the 8-bit I/O fifo port specified by Port.
>> +  The port is read Count times, and the read data is
>> +  stored in the provided Buffer.
>> +
>> +  This function must guarantee that all I/O read and write operations are
>> +  serialized.
>> +
>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port    The I/O port to read.
>> +  @param  Count   The number of times to read I/O port.
>> +  @param  Buffer  The buffer to store the read data into.
>> +
>> +**/
>> +VOID
>> +EFIAPI
>> +IoReadFifo8 (
>> +  IN      UINTN                     Port,
>> +  IN      UINTN                     Count,
>> +  OUT     VOID                      *Buffer
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +}
>> +
>> +/**
>> +  Writes a block of memory into an 8-bit I/O port fifo.
>> +
>> +  Writes the 8-bit I/O fifo port specified by Port.
>> +  The port is written Count times, and the write data is
>> +  retrieved from the provided Buffer.
>> +
>> +  This function must guarantee that all I/O write and write operations are
>> +  serialized.
>> +
>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port    The I/O port to write.
>> +  @param  Count   The number of times to write I/O port.
>> +  @param  Buffer  The buffer to retrieve the write data from.
>> +
>> +**/
>> +VOID
>> +EFIAPI
>> +IoWriteFifo8 (
>> +  IN      UINTN                     Port,
>> +  IN      UINTN                     Count,
>> +  IN      VOID                      *Buffer
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +}
>> +
>> +/**
>> +  Reads a 16-bit I/O port fifo into a block of memory.
>> +
>> +  Reads the 16-bit I/O fifo port specified by Port.
>> +  The port is read Count times, and the read data is
>> +  stored in the provided Buffer.
>> +
>> +  This function must guarantee that all I/O read and write operations are
>> +  serialized.
>> +
>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port    The I/O port to read.
>> +  @param  Count   The number of times to read I/O port.
>> +  @param  Buffer  The buffer to store the read data into.
>> +
>> +**/
>> +VOID
>> +EFIAPI
>> +IoReadFifo16 (
>> +  IN      UINTN                     Port,
>> +  IN      UINTN                     Count,
>> +  OUT     VOID                      *Buffer
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +}
>> +
>> +/**
>> +  Writes a block of memory into a 16-bit I/O port fifo.
>> +
>> +  Writes the 16-bit I/O fifo port specified by Port.
>> +  The port is written Count times, and the write data is
>> +  retrieved from the provided Buffer.
>> +
>> +  This function must guarantee that all I/O write and write operations are
>> +  serialized.
>> +
>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port    The I/O port to write.
>> +  @param  Count   The number of times to write I/O port.
>> +  @param  Buffer  The buffer to retrieve the write data from.
>> +
>> +**/
>> +VOID
>> +EFIAPI
>> +IoWriteFifo16 (
>> +  IN      UINTN                     Port,
>> +  IN      UINTN                     Count,
>> +  IN      VOID                      *Buffer
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +}
>> +
>> +/**
>> +  Reads a 32-bit I/O port fifo into a block of memory.
>> +
>> +  Reads the 32-bit I/O fifo port specified by Port.
>> +  The port is read Count times, and the read data is
>> +  stored in the provided Buffer.
>> +
>> +  This function must guarantee that all I/O read and write operations are
>> +  serialized.
>> +
>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port    The I/O port to read.
>> +  @param  Count   The number of times to read I/O port.
>> +  @param  Buffer  The buffer to store the read data into.
>> +
>> +**/
>> +VOID
>> +EFIAPI
>> +IoReadFifo32 (
>> +  IN      UINTN                     Port,
>> +  IN      UINTN                     Count,
>> +  OUT     VOID                      *Buffer
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +}
>> +
>> +/**
>> +  Writes a block of memory into a 32-bit I/O port fifo.
>> +
>> +  Writes the 32-bit I/O fifo port specified by Port.
>> +  The port is written Count times, and the write data is
>> +  retrieved from the provided Buffer.
>> +
>> +  This function must guarantee that all I/O write and write operations are
>> +  serialized.
>> +
>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> +
>> +  @param  Port    The I/O port to write.
>> +  @param  Count   The number of times to write I/O port.
>> +  @param  Buffer  The buffer to retrieve the write data from.
>> +
>> +**/
>> +VOID
>> +EFIAPI
>> +IoWriteFifo32 (
>> +  IN      UINTN                     Port,
>> +  IN      UINTN                     Count,
>> +  IN      VOID                      *Buffer
>> +  )
>> +{
>> +  ASSERT (FALSE);
>> +}
>> +
>> +/**
>> +  Reads an 8-bit MMIO register.
>> +
>> +  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> +  returned. This function must guarantee that all MMIO read and write
>> +  operations are serialized.
>> +
>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT8
>> +EFIAPI
>> +MmioRead8 (
>> +  IN      UINTN                     Address
>> +  )
>> +{
>> +  return MmioRead8Internal (Address);
>> +}
>> +
>> +/**
>> +  Writes an 8-bit MMIO register.
>> +
>> +  Writes the 8-bit MMIO register specified by Address with the value specified
>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> +  and write operations are serialized.
>> +
>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to write.
>> +  @param  Value   The value to write to the MMIO register.
>> +
>> +**/
>> +UINT8
>> +EFIAPI
>> +MmioWrite8 (
>> +  IN      UINTN                     Address,
>> +  IN      UINT8                     Value
>> +  )
>> +{
>> +  MmioWrite8Internal (Address, Value);
>> +  return Value;
>> +}
>> +
>> +/**
>> +  Reads a 16-bit MMIO register.
>> +
>> +  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> +  returned. This function must guarantee that all MMIO read and write
>> +  operations are serialized.
>> +
>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT16
>> +EFIAPI
>> +MmioRead16 (
>> +  IN      UINTN                     Address
>> +  )
>> +{
>> +  ASSERT ((Address & 1) == 0);
>> +
>> +  return MmioRead16Internal (Address);
>> +}
>> +
>> +/**
>> +  Writes a 16-bit MMIO register.
>> +
>> +  Writes the 16-bit MMIO register specified by Address with the value specified
>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> +  and write operations are serialized.
>> +
>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to write.
>> +  @param  Value   The value to write to the MMIO register.
>> +
>> +**/
>> +UINT16
>> +EFIAPI
>> +MmioWrite16 (
>> +  IN      UINTN                     Address,
>> +  IN      UINT16                    Value
>> +  )
>> +{
>> +  ASSERT ((Address & 1) == 0);
>> +
>> +  MmioWrite16Internal (Address, Value);
>> +  return Value;
>> +}
>> +
>> +/**
>> +  Reads a 32-bit MMIO register.
>> +
>> +  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> +  returned. This function must guarantee that all MMIO read and write
>> +  operations are serialized.
>> +
>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT32
>> +EFIAPI
>> +MmioRead32 (
>> +  IN      UINTN                     Address
>> +  )
>> +{
>> +  ASSERT ((Address & 3) == 0);
>> +
>> +  return MmioRead32Internal (Address);
>> +}
>> +
>> +/**
>> +  Writes a 32-bit MMIO register.
>> +
>> +  Writes the 32-bit MMIO register specified by Address with the value specified
>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> +  and write operations are serialized.
>> +
>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to write.
>> +  @param  Value   The value to write to the MMIO register.
>> +
>> +**/
>> +UINT32
>> +EFIAPI
>> +MmioWrite32 (
>> +  IN      UINTN                     Address,
>> +  IN      UINT32                    Value
>> +  )
>> +{
>> +  ASSERT ((Address & 3) == 0);
>> +
>> +  MmioWrite32Internal (Address, Value);
>> +  return Value;
>> +}
>> +
>> +/**
>> +  Reads a 64-bit MMIO register.
>> +
>> +  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> +  returned. This function must guarantee that all MMIO read and write
>> +  operations are serialized.
>> +
>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to read.
>> +
>> +  @return The value read.
>> +
>> +**/
>> +UINT64
>> +EFIAPI
>> +MmioRead64 (
>> +  IN      UINTN                     Address
>> +  )
>> +{
>> +  ASSERT ((Address & 7) == 0);
>> +
>> +  return MmioRead64Internal (Address);
>> +}
>> +
>> +/**
>> +  Writes a 64-bit MMIO register.
>> +
>> +  Writes the 64-bit MMIO register specified by Address with the value specified
>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> +  and write operations are serialized.
>> +
>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
>> +
>> +  @param  Address The MMIO register to write.
>> +  @param  Value   The value to write to the MMIO register.
>> +
>> +**/
>> +UINT64
>> +EFIAPI
>> +MmioWrite64 (
>> +  IN      UINTN                     Address,
>> +  IN      UINT64                    Value
>> +  )
>> +{
>> +  ASSERT ((Address & 7) == 0);
>> +
>> +  MmioWrite64Internal (Address, Value);
>> +  return Value;
>> +}
>> --
>> 2.17.0
>
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Re: [edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Posted by Laszlo Ersek, 2 weeks ago
On 06/07/18 17:09, Ard Biesheuvel wrote:
> On 7 June 2018 at 17:08, Gao, Liming <liming.gao@intel.com> wrote:
>> Ard:
>>   If this library instance is specific to ARM emulator with KVM, how about add it into ArmVirtPkg?
>>
> 
> Laszlo, do you want to take this question?

Certainly.

Liming, in commit b6d11d7c4678, we added "BaseIoLibIntrinsicSev.inf" to
"MdePkg/Library/BaseIoLibIntrinsic", with some custom Ia32 and X64 NASM
files, but mostly reusing the large existent files ("IoLibMmioBuffer.c",
"IoHighLevel.c" etc).

That library instance (and the NASM customizations) target AMD SEV; that
is, when the code runs in a virtual machine for which AMD Secure
Encrypted Virtualization is enabled. The NASM code uses CPUID to
dynamically determine whether it runs in a SEV guest, or in a normal
guest, and in the former case, it avoids using the REP prefix in the
IoFifo routines (it uses open-coded LOOPs).

The "BaseIoLibIntrinsicSev.inf" instance is only ever used in OvmfPkg
(it only makes sense in virtual machines), but the consensus back then
was to add the lib instance to MdePkg.


This time, Ard has already implemented (and posted) the IoLib instance
that we need for ARM KVM such that it lands under ArmVirtPkg -- however,
that library instance duplicates a huge amount of code, un-changed, from
"BaseIoLibIntrinsic" (such as "IoLibMmioBuffer.c", "IoHighLevel.c"). I
suggested that Ard instead post the new library instance as a new INF
file (plus some assembly files) for BaseIoLibIntrinsic itself, because:
(a) this way we avoid code duplication, and (b) that's exactly what we
did -- for another virtualization-only use case -- in commit
b6d11d7c4678 earlier.

If you'd like us to add the code to ArmVirtPkg, I don't think that's the
right or consequent action, but technically, we can simply fall back to
the ArmVirtPkg patches that Ard already wrote and posted.

Thanks,
Laszlo

>>> -----Original Message-----
>>> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>>> Sent: Thursday, June 7, 2018 6:47 PM
>>> To: edk2-devel@lists.01.org
>>> Cc: lersek@redhat.com; leif.lindholm@linaro.org; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
>>> <michael.d.kinney@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>> Subject: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
>>>
>>> KVM on ARM refuses to decode load/store instructions used to perform
>>> I/O to emulated devices, and instead relies on the exception syndrome
>>> information to describe the operand register, access size, etc.
>>> This is only possible for instructions that have a single input/output
>>> register (as opposed to ones that increment the offset register, or
>>> load/store pair instructions, etc). Otherwise, QEMU crashes with the
>>> following error
>>>
>>>   error: kvm run failed Function not implemented
>>>   R00=01010101 R01=00000008 R02=00000048 R03=08000820
>>>   R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8
>>>   R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080
>>>   R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c
>>>   PSR=800001f3 N--- T svc32
>>>   QEMU: Terminated
>>>
>>> and KVM produces a warning such as the following in the kernel log
>>>
>>>   kvm [17646]: load/store instruction decoding not implemented
>>>
>>> The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic
>>> is based on C code, and when LTO is in effect, the MMIO accesses could
>>> be merged with, e.g., manipulations of the loop counter, producing
>>> opcodes that KVM does not support for emulated MMIO.
>>>
>>> So let's add a special ArmVirt flavor of this library that implements
>>> that actual load/store operations in assembler, ensuring that the
>>> instructions involved can be emulated by KVM.
>>>
>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>> ---
>>>  ArmVirtPkg/ArmVirt.dsc.inc                                      |   2 +-
>>>  MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S         | 164 +++++
>>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S             | 161 +++++
>>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm           | 165 +++++
>>>  MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf |  50 ++
>>>  MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c                | 641 ++++++++++++++++++++
>>>  6 files changed, 1182 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/ArmVirtPkg/ArmVirt.dsc.inc b/ArmVirtPkg/ArmVirt.dsc.inc
>>> index 766e4f598a07..7464ac70ed1b 100644
>>> --- a/ArmVirtPkg/ArmVirt.dsc.inc
>>> +++ b/ArmVirtPkg/ArmVirt.dsc.inc
>>> @@ -41,7 +41,7 @@ [LibraryClasses.common]
>>>    PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
>>>    PeCoffGetEntryPointLib|MdePkg/Library/BasePeCoffGetEntryPointLib/BasePeCoffGetEntryPointLib.inf
>>>    PeCoffLib|MdePkg/Library/BasePeCoffLib/BasePeCoffLib.inf
>>> -  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>>> +  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>>>    UefiDecompressLib|MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.inf
>>>    CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf
>>>
>>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
>>> new file mode 100644
>>> index 000000000000..47be68a3e783
>>> --- /dev/null
>>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
>>> @@ -0,0 +1,164 @@
>>> +#
>>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>>> +#
>>> +#  This program and the accompanying materials are licensed and made available
>>> +#  under the terms and conditions of the BSD License which accompanies this
>>> +#  distribution.  The full text of the license may be found at
>>> +#  http://opensource.org/licenses/bsd-license.php
>>> +#
>>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>>> +#
>>> +#
>>> +
>>> +.text
>>> +.align 3
>>> +
>>> +GCC_ASM_EXPORT(MmioRead8Internal)
>>> +GCC_ASM_EXPORT(MmioWrite8Internal)
>>> +GCC_ASM_EXPORT(MmioRead16Internal)
>>> +GCC_ASM_EXPORT(MmioWrite16Internal)
>>> +GCC_ASM_EXPORT(MmioRead32Internal)
>>> +GCC_ASM_EXPORT(MmioWrite32Internal)
>>> +GCC_ASM_EXPORT(MmioRead64Internal)
>>> +GCC_ASM_EXPORT(MmioWrite64Internal)
>>> +
>>> +//
>>> +//  Reads an 8-bit MMIO register.
>>> +//
>>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead8Internal):
>>> +  ldrb    w0, [x0]
>>> +  dmb     ld
>>> +  ret
>>> +
>>> +//
>>> +//  Writes an 8-bit MMIO register.
>>> +//
>>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite8Internal):
>>> +  dmb     st
>>> +  strb    w1, [x0]
>>> +  ret
>>> +
>>> +//
>>> +//  Reads a 16-bit MMIO register.
>>> +//
>>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead16Internal):
>>> +  ldrh    w0, [x0]
>>> +  dmb     ld
>>> +  ret
>>> +
>>> +//
>>> +//  Writes a 16-bit MMIO register.
>>> +//
>>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite16Internal):
>>> +  dmb     st
>>> +  strh    w1, [x0]
>>> +  ret
>>> +
>>> +//
>>> +//  Reads a 32-bit MMIO register.
>>> +//
>>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead32Internal):
>>> +  ldr     w0, [x0]
>>> +  dmb     ld
>>> +  ret
>>> +
>>> +//
>>> +//  Writes a 32-bit MMIO register.
>>> +//
>>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite32Internal):
>>> +  dmb     st
>>> +  str     w1, [x0]
>>> +  ret
>>> +
>>> +//
>>> +//  Reads a 64-bit MMIO register.
>>> +//
>>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead64Internal):
>>> +  ldr     x0, [x0]
>>> +  dmb     ld
>>> +  ret
>>> +
>>> +//
>>> +//  Writes a 64-bit MMIO register.
>>> +//
>>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite64Internal):
>>> +  dmb     st
>>> +  str     x1, [x0]
>>> +  ret
>>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
>>> new file mode 100644
>>> index 000000000000..438805ca7c24
>>> --- /dev/null
>>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
>>> @@ -0,0 +1,161 @@
>>> +#
>>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>>> +#
>>> +#  This program and the accompanying materials are licensed and made available
>>> +#  under the terms and conditions of the BSD License which accompanies this
>>> +#  distribution.  The full text of the license may be found at
>>> +#  http://opensource.org/licenses/bsd-license.php
>>> +#
>>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>>> +#
>>> +#
>>> +
>>> +GCC_ASM_EXPORT(MmioRead8Internal)
>>> +GCC_ASM_EXPORT(MmioWrite8Internal)
>>> +GCC_ASM_EXPORT(MmioRead16Internal)
>>> +GCC_ASM_EXPORT(MmioWrite16Internal)
>>> +GCC_ASM_EXPORT(MmioRead32Internal)
>>> +GCC_ASM_EXPORT(MmioWrite32Internal)
>>> +GCC_ASM_EXPORT(MmioRead64Internal)
>>> +GCC_ASM_EXPORT(MmioWrite64Internal)
>>> +
>>> +//
>>> +//  Reads an 8-bit MMIO register.
>>> +//
>>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead8Internal):
>>> +  ldrb    r0, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +//
>>> +//  Writes an 8-bit MMIO register.
>>> +//
>>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite8Internal):
>>> +  dmb     st
>>> +  strb    r1, [r0]
>>> +  bx      lr
>>> +
>>> +//
>>> +//  Reads a 16-bit MMIO register.
>>> +//
>>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead16Internal):
>>> +  ldrh    r0, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +//
>>> +//  Writes a 16-bit MMIO register.
>>> +//
>>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite16Internal):
>>> +  dmb     st
>>> +  strh    r1, [r0]
>>> +  bx      lr
>>> +
>>> +//
>>> +//  Reads a 32-bit MMIO register.
>>> +//
>>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead32Internal):
>>> +  ldr     r0, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +//
>>> +//  Writes a 32-bit MMIO register.
>>> +//
>>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite32Internal):
>>> +  dmb     st
>>> +  str     r1, [r0]
>>> +  bx      lr
>>> +
>>> +//
>>> +//  Reads a 64-bit MMIO register.
>>> +//
>>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>>> +//  returned. This function must guarantee that all MMIO read and write
>>> +//  operations are serialized.
>>> +//
>>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to read.
>>> +//
>>> +//  @return The value read.
>>> +//
>>> +ASM_PFX(MmioRead64Internal):
>>> +  ldrd    r0, r1, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +//
>>> +//  Writes a 64-bit MMIO register.
>>> +//
>>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
>>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>>> +//  and write operations are serialized.
>>> +//
>>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +//
>>> +//  @param  Address The MMIO register to write.
>>> +//  @param  Value   The value to write to the MMIO register.
>>> +//
>>> +ASM_PFX(MmioWrite64Internal):
>>> +  dmb     st
>>> +  strd    r2, r3, [r0]
>>> +  bx      lr
>>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
>>> new file mode 100644
>>> index 000000000000..82add82f800a
>>> --- /dev/null
>>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
>>> @@ -0,0 +1,165 @@
>>> +;
>>> +;  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>>> +;
>>> +;  This program and the accompanying materials are licensed and made available
>>> +;  under the terms and conditions of the BSD License which accompanies this
>>> +;  distribution.  The full text of the license may be found at
>>> +;  http:;opensource.org/licenses/bsd-license.php
>>> +;
>>> +;  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>>> +;  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>>> +;
>>> +
>>> +
>>> +AREA IoLibMmio, CODE, READONLY
>>> +
>>> +EXPORT MmioRead8Internal
>>> +EXPORT MmioWrite8Internal
>>> +EXPORT MmioRead16Internal
>>> +EXPORT MmioWrite16Internal
>>> +EXPORT MmioRead32Internal
>>> +EXPORT MmioWrite32Internal
>>> +EXPORT MmioRead64Internal
>>> +EXPORT MmioWrite64Internal
>>> +
>>> +;
>>> +;  Reads an 8-bit MMIO register.
>>> +;
>>> +;  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>>> +;  returned. This function must guarantee that all MMIO read and write
>>> +;  operations are serialized.
>>> +;
>>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to read.
>>> +;
>>> +;  @return The value read.
>>> +;
>>> +MmioRead8Internal
>>> +  ldrb    r0, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +;
>>> +;  Writes an 8-bit MMIO register.
>>> +;
>>> +;  Writes the 8-bit MMIO register specified by Address with the value specified
>>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>>> +;  and write operations are serialized.
>>> +;
>>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to write.
>>> +;  @param  Value   The value to write to the MMIO register.
>>> +;
>>> +MmioWrite8Internal
>>> +  dmb     st
>>> +  strb    r1, [r0]
>>> +  bx      lr
>>> +
>>> +;
>>> +;  Reads a 16-bit MMIO register.
>>> +;
>>> +;  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>>> +;  returned. This function must guarantee that all MMIO read and write
>>> +;  operations are serialized.
>>> +;
>>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to read.
>>> +;
>>> +;  @return The value read.
>>> +;
>>> +MmioRead16Internal
>>> +  ldrh    r0, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +;
>>> +;  Writes a 16-bit MMIO register.
>>> +;
>>> +;  Writes the 16-bit MMIO register specified by Address with the value specified
>>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>>> +;  and write operations are serialized.
>>> +;
>>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to write.
>>> +;  @param  Value   The value to write to the MMIO register.
>>> +;
>>> +MmioWrite16Internal
>>> +  dmb     st
>>> +  strh    r1, [r0]
>>> +  bx      lr
>>> +
>>> +;
>>> +;  Reads a 32-bit MMIO register.
>>> +;
>>> +;  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>>> +;  returned. This function must guarantee that all MMIO read and write
>>> +;  operations are serialized.
>>> +;
>>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to read.
>>> +;
>>> +;  @return The value read.
>>> +;
>>> +MmioRead32Internal
>>> +  ldr     r0, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +;
>>> +;  Writes a 32-bit MMIO register.
>>> +;
>>> +;  Writes the 32-bit MMIO register specified by Address with the value specified
>>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>>> +;  and write operations are serialized.
>>> +;
>>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to write.
>>> +;  @param  Value   The value to write to the MMIO register.
>>> +;
>>> +MmioWrite32Internal
>>> +  dmb     st
>>> +  str     r1, [r0]
>>> +  bx      lr
>>> +
>>> +;
>>> +;  Reads a 64-bit MMIO register.
>>> +;
>>> +;  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>>> +;  returned. This function must guarantee that all MMIO read and write
>>> +;  operations are serialized.
>>> +;
>>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to read.
>>> +;
>>> +;  @return The value read.
>>> +;
>>> +MmioRead64Internal
>>> +  ldrd    r0, r1, [r0]
>>> +  dmb
>>> +  bx      lr
>>> +
>>> +;
>>> +;  Writes a 64-bit MMIO register.
>>> +;
>>> +;  Writes the 64-bit MMIO register specified by Address with the value specified
>>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>>> +;  and write operations are serialized.
>>> +;
>>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +;
>>> +;  @param  Address The MMIO register to write.
>>> +;  @param  Value   The value to write to the MMIO register.
>>> +;
>>> +MmioWrite64Internal
>>> +  dmb     st
>>> +  strd    r2, r3, [r0]
>>> +  bx      lr
>>> +
>>> +  END
>>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>>> b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>>> new file mode 100644
>>> index 000000000000..5a1dc87ed2bd
>>> --- /dev/null
>>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>>> @@ -0,0 +1,50 @@
>>> +## @file
>>> +#  Instance of I/O Library using KVM/ARM safe assembler routines
>>> +#
>>> +#  Copyright (c) 2007 - 2015, Intel Corporation. All rights reserved.<BR>
>>> +#  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
>>> +#  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>>> +#  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
>>> +#
>>> +#  This program and the accompanying materials are licensed and made available
>>> +#  under the terms and conditions of the BSD License which accompanies this
>>> +#  distribution. The full text of the license may be found at
>>> +#  http://opensource.org/licenses/bsd-license.php.
>>> +#
>>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>>> +#
>>> +##
>>> +
>>> +[Defines]
>>> +  INF_VERSION                    = 0x0001001A
>>> +  BASE_NAME                      = BaseIoLibIntrinsicArmVirt
>>> +  FILE_GUID                      = 217102b4-b465-4a1d-a2de-93dd385ec480
>>> +  MODULE_TYPE                    = BASE
>>> +  VERSION_STRING                 = 1.0
>>> +  LIBRARY_CLASS                  = IoLib
>>> +
>>> +#
>>> +#  VALID_ARCHITECTURES           = ARM AARCH64
>>> +#
>>> +
>>> +[Sources]
>>> +  IoLibMmioBuffer.c
>>> +  BaseIoLibIntrinsicInternal.h
>>> +  IoHighLevel.c
>>> +
>>> +[Sources.ARM]
>>> +  IoLibArmVirt.c
>>> +  Arm/ArmVirtMmio.S   | GCC
>>> +  Arm/ArmVirtMmio.asm | RVCT
>>> +
>>> +[Sources.AARCH64]
>>> +  IoLibArmVirt.c
>>> +  AArch64/ArmVirtMmio.S
>>> +
>>> +[Packages]
>>> +  MdePkg/MdePkg.dec
>>> +
>>> +[LibraryClasses]
>>> +  DebugLib
>>> +  BaseLib
>>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
>>> new file mode 100644
>>> index 000000000000..154d583246ac
>>> --- /dev/null
>>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
>>> @@ -0,0 +1,641 @@
>>> +/** @file
>>> +  I/O Library for ARM.
>>> +
>>> +  Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
>>> +  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
>>> +  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>>> +  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
>>> +
>>> +  This program and the accompanying materials are licensed and made available
>>> +  under the terms and conditions of the BSD License which accompanies this
>>> +  distribution. The full text of the license may be found at
>>> +  http://opensource.org/licenses/bsd-license.php.
>>> +
>>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>>> +  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>>> +
>>> +**/
>>> +
>>> +#include "BaseIoLibIntrinsicInternal.h"
>>> +
>>> +UINT8
>>> +EFIAPI
>>> +MmioRead8Internal (
>>> +  IN      UINTN                     Address
>>> +  );
>>> +
>>> +VOID
>>> +EFIAPI
>>> +MmioWrite8Internal (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT8                     Value
>>> +  );
>>> +
>>> +UINT16
>>> +EFIAPI
>>> +MmioRead16Internal (
>>> +  IN      UINTN                     Address
>>> +  );
>>> +
>>> +VOID
>>> +EFIAPI
>>> +MmioWrite16Internal (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT16                    Value
>>> +  );
>>> +
>>> +UINT32
>>> +EFIAPI
>>> +MmioRead32Internal (
>>> +  IN      UINTN                     Address
>>> +  );
>>> +
>>> +VOID
>>> +EFIAPI
>>> +MmioWrite32Internal (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT32                    Value
>>> +  );
>>> +
>>> +UINT64
>>> +EFIAPI
>>> +MmioRead64Internal (
>>> +  IN      UINTN                     Address
>>> +  );
>>> +
>>> +VOID
>>> +EFIAPI
>>> +MmioWrite64Internal (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT64                    Value
>>> +  );
>>> +
>>> +/**
>>> +  Reads an 8-bit I/O port.
>>> +
>>> +  Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
>>> +  This function must guarantee that all I/O read and write operations are
>>> +  serialized.
>>> +
>>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT8
>>> +EFIAPI
>>> +IoRead8 (
>>> +  IN      UINTN                     Port
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return 0;
>>> +}
>>> +
>>> +/**
>>> +  Writes an 8-bit I/O port.
>>> +
>>> +  Writes the 8-bit I/O port specified by Port with the value specified by Value
>>> +  and returns Value. This function must guarantee that all I/O read and write
>>> +  operations are serialized.
>>> +
>>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to write.
>>> +  @param  Value The value to write to the I/O port.
>>> +
>>> +  @return The value written the I/O port.
>>> +
>>> +**/
>>> +UINT8
>>> +EFIAPI
>>> +IoWrite8 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINT8                     Value
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return Value;
>>> +}
>>> +
>>> +/**
>>> +  Reads a 16-bit I/O port.
>>> +
>>> +  Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
>>> +  This function must guarantee that all I/O read and write operations are
>>> +  serialized.
>>> +
>>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT16
>>> +EFIAPI
>>> +IoRead16 (
>>> +  IN      UINTN                     Port
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return 0;
>>> +}
>>> +
>>> +/**
>>> +  Writes a 16-bit I/O port.
>>> +
>>> +  Writes the 16-bit I/O port specified by Port with the value specified by Value
>>> +  and returns Value. This function must guarantee that all I/O read and write
>>> +  operations are serialized.
>>> +
>>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to write.
>>> +  @param  Value The value to write to the I/O port.
>>> +
>>> +  @return The value written the I/O port.
>>> +
>>> +**/
>>> +UINT16
>>> +EFIAPI
>>> +IoWrite16 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINT16                    Value
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return Value;
>>> +}
>>> +
>>> +/**
>>> +  Reads a 32-bit I/O port.
>>> +
>>> +  Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
>>> +  This function must guarantee that all I/O read and write operations are
>>> +  serialized.
>>> +
>>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT32
>>> +EFIAPI
>>> +IoRead32 (
>>> +  IN      UINTN                     Port
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return 0;
>>> +}
>>> +
>>> +/**
>>> +  Writes a 32-bit I/O port.
>>> +
>>> +  Writes the 32-bit I/O port specified by Port with the value specified by Value
>>> +  and returns Value. This function must guarantee that all I/O read and write
>>> +  operations are serialized.
>>> +
>>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to write.
>>> +  @param  Value The value to write to the I/O port.
>>> +
>>> +  @return The value written the I/O port.
>>> +
>>> +**/
>>> +UINT32
>>> +EFIAPI
>>> +IoWrite32 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINT32                    Value
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return Value;
>>> +}
>>> +
>>> +/**
>>> +  Reads a 64-bit I/O port.
>>> +
>>> +  Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
>>> +  This function must guarantee that all I/O read and write operations are
>>> +  serialized.
>>> +
>>> +  If 64-bit I/O port operations are not supported, then ASSERT().
>>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT64
>>> +EFIAPI
>>> +IoRead64 (
>>> +  IN      UINTN                     Port
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return 0;
>>> +}
>>> +
>>> +/**
>>> +  Writes a 64-bit I/O port.
>>> +
>>> +  Writes the 64-bit I/O port specified by Port with the value specified by Value
>>> +  and returns Value. This function must guarantee that all I/O read and write
>>> +  operations are serialized.
>>> +
>>> +  If 64-bit I/O port operations are not supported, then ASSERT().
>>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
>>> +
>>> +  @param  Port  The I/O port to write.
>>> +  @param  Value The value to write to the I/O port.
>>> +
>>> +  @return The value written to the I/O port.
>>> +
>>> +**/
>>> +UINT64
>>> +EFIAPI
>>> +IoWrite64 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINT64                    Value
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return 0;
>>> +}
>>> +
>>> +/**
>>> +  Reads an 8-bit I/O port fifo into a block of memory.
>>> +
>>> +  Reads the 8-bit I/O fifo port specified by Port.
>>> +  The port is read Count times, and the read data is
>>> +  stored in the provided Buffer.
>>> +
>>> +  This function must guarantee that all I/O read and write operations are
>>> +  serialized.
>>> +
>>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port    The I/O port to read.
>>> +  @param  Count   The number of times to read I/O port.
>>> +  @param  Buffer  The buffer to store the read data into.
>>> +
>>> +**/
>>> +VOID
>>> +EFIAPI
>>> +IoReadFifo8 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINTN                     Count,
>>> +  OUT     VOID                      *Buffer
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +}
>>> +
>>> +/**
>>> +  Writes a block of memory into an 8-bit I/O port fifo.
>>> +
>>> +  Writes the 8-bit I/O fifo port specified by Port.
>>> +  The port is written Count times, and the write data is
>>> +  retrieved from the provided Buffer.
>>> +
>>> +  This function must guarantee that all I/O write and write operations are
>>> +  serialized.
>>> +
>>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port    The I/O port to write.
>>> +  @param  Count   The number of times to write I/O port.
>>> +  @param  Buffer  The buffer to retrieve the write data from.
>>> +
>>> +**/
>>> +VOID
>>> +EFIAPI
>>> +IoWriteFifo8 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINTN                     Count,
>>> +  IN      VOID                      *Buffer
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +}
>>> +
>>> +/**
>>> +  Reads a 16-bit I/O port fifo into a block of memory.
>>> +
>>> +  Reads the 16-bit I/O fifo port specified by Port.
>>> +  The port is read Count times, and the read data is
>>> +  stored in the provided Buffer.
>>> +
>>> +  This function must guarantee that all I/O read and write operations are
>>> +  serialized.
>>> +
>>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port    The I/O port to read.
>>> +  @param  Count   The number of times to read I/O port.
>>> +  @param  Buffer  The buffer to store the read data into.
>>> +
>>> +**/
>>> +VOID
>>> +EFIAPI
>>> +IoReadFifo16 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINTN                     Count,
>>> +  OUT     VOID                      *Buffer
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +}
>>> +
>>> +/**
>>> +  Writes a block of memory into a 16-bit I/O port fifo.
>>> +
>>> +  Writes the 16-bit I/O fifo port specified by Port.
>>> +  The port is written Count times, and the write data is
>>> +  retrieved from the provided Buffer.
>>> +
>>> +  This function must guarantee that all I/O write and write operations are
>>> +  serialized.
>>> +
>>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port    The I/O port to write.
>>> +  @param  Count   The number of times to write I/O port.
>>> +  @param  Buffer  The buffer to retrieve the write data from.
>>> +
>>> +**/
>>> +VOID
>>> +EFIAPI
>>> +IoWriteFifo16 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINTN                     Count,
>>> +  IN      VOID                      *Buffer
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +}
>>> +
>>> +/**
>>> +  Reads a 32-bit I/O port fifo into a block of memory.
>>> +
>>> +  Reads the 32-bit I/O fifo port specified by Port.
>>> +  The port is read Count times, and the read data is
>>> +  stored in the provided Buffer.
>>> +
>>> +  This function must guarantee that all I/O read and write operations are
>>> +  serialized.
>>> +
>>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port    The I/O port to read.
>>> +  @param  Count   The number of times to read I/O port.
>>> +  @param  Buffer  The buffer to store the read data into.
>>> +
>>> +**/
>>> +VOID
>>> +EFIAPI
>>> +IoReadFifo32 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINTN                     Count,
>>> +  OUT     VOID                      *Buffer
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +}
>>> +
>>> +/**
>>> +  Writes a block of memory into a 32-bit I/O port fifo.
>>> +
>>> +  Writes the 32-bit I/O fifo port specified by Port.
>>> +  The port is written Count times, and the write data is
>>> +  retrieved from the provided Buffer.
>>> +
>>> +  This function must guarantee that all I/O write and write operations are
>>> +  serialized.
>>> +
>>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>>> +
>>> +  @param  Port    The I/O port to write.
>>> +  @param  Count   The number of times to write I/O port.
>>> +  @param  Buffer  The buffer to retrieve the write data from.
>>> +
>>> +**/
>>> +VOID
>>> +EFIAPI
>>> +IoWriteFifo32 (
>>> +  IN      UINTN                     Port,
>>> +  IN      UINTN                     Count,
>>> +  IN      VOID                      *Buffer
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +}
>>> +
>>> +/**
>>> +  Reads an 8-bit MMIO register.
>>> +
>>> +  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>>> +  returned. This function must guarantee that all MMIO read and write
>>> +  operations are serialized.
>>> +
>>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT8
>>> +EFIAPI
>>> +MmioRead8 (
>>> +  IN      UINTN                     Address
>>> +  )
>>> +{
>>> +  return MmioRead8Internal (Address);
>>> +}
>>> +
>>> +/**
>>> +  Writes an 8-bit MMIO register.
>>> +
>>> +  Writes the 8-bit MMIO register specified by Address with the value specified
>>> +  by Value and returns Value. This function must guarantee that all MMIO read
>>> +  and write operations are serialized.
>>> +
>>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to write.
>>> +  @param  Value   The value to write to the MMIO register.
>>> +
>>> +**/
>>> +UINT8
>>> +EFIAPI
>>> +MmioWrite8 (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT8                     Value
>>> +  )
>>> +{
>>> +  MmioWrite8Internal (Address, Value);
>>> +  return Value;
>>> +}
>>> +
>>> +/**
>>> +  Reads a 16-bit MMIO register.
>>> +
>>> +  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>>> +  returned. This function must guarantee that all MMIO read and write
>>> +  operations are serialized.
>>> +
>>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT16
>>> +EFIAPI
>>> +MmioRead16 (
>>> +  IN      UINTN                     Address
>>> +  )
>>> +{
>>> +  ASSERT ((Address & 1) == 0);
>>> +
>>> +  return MmioRead16Internal (Address);
>>> +}
>>> +
>>> +/**
>>> +  Writes a 16-bit MMIO register.
>>> +
>>> +  Writes the 16-bit MMIO register specified by Address with the value specified
>>> +  by Value and returns Value. This function must guarantee that all MMIO read
>>> +  and write operations are serialized.
>>> +
>>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to write.
>>> +  @param  Value   The value to write to the MMIO register.
>>> +
>>> +**/
>>> +UINT16
>>> +EFIAPI
>>> +MmioWrite16 (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT16                    Value
>>> +  )
>>> +{
>>> +  ASSERT ((Address & 1) == 0);
>>> +
>>> +  MmioWrite16Internal (Address, Value);
>>> +  return Value;
>>> +}
>>> +
>>> +/**
>>> +  Reads a 32-bit MMIO register.
>>> +
>>> +  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>>> +  returned. This function must guarantee that all MMIO read and write
>>> +  operations are serialized.
>>> +
>>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT32
>>> +EFIAPI
>>> +MmioRead32 (
>>> +  IN      UINTN                     Address
>>> +  )
>>> +{
>>> +  ASSERT ((Address & 3) == 0);
>>> +
>>> +  return MmioRead32Internal (Address);
>>> +}
>>> +
>>> +/**
>>> +  Writes a 32-bit MMIO register.
>>> +
>>> +  Writes the 32-bit MMIO register specified by Address with the value specified
>>> +  by Value and returns Value. This function must guarantee that all MMIO read
>>> +  and write operations are serialized.
>>> +
>>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to write.
>>> +  @param  Value   The value to write to the MMIO register.
>>> +
>>> +**/
>>> +UINT32
>>> +EFIAPI
>>> +MmioWrite32 (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT32                    Value
>>> +  )
>>> +{
>>> +  ASSERT ((Address & 3) == 0);
>>> +
>>> +  MmioWrite32Internal (Address, Value);
>>> +  return Value;
>>> +}
>>> +
>>> +/**
>>> +  Reads a 64-bit MMIO register.
>>> +
>>> +  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>>> +  returned. This function must guarantee that all MMIO read and write
>>> +  operations are serialized.
>>> +
>>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to read.
>>> +
>>> +  @return The value read.
>>> +
>>> +**/
>>> +UINT64
>>> +EFIAPI
>>> +MmioRead64 (
>>> +  IN      UINTN                     Address
>>> +  )
>>> +{
>>> +  ASSERT ((Address & 7) == 0);
>>> +
>>> +  return MmioRead64Internal (Address);
>>> +}
>>> +
>>> +/**
>>> +  Writes a 64-bit MMIO register.
>>> +
>>> +  Writes the 64-bit MMIO register specified by Address with the value specified
>>> +  by Value and returns Value. This function must guarantee that all MMIO read
>>> +  and write operations are serialized.
>>> +
>>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
>>> +
>>> +  @param  Address The MMIO register to write.
>>> +  @param  Value   The value to write to the MMIO register.
>>> +
>>> +**/
>>> +UINT64
>>> +EFIAPI
>>> +MmioWrite64 (
>>> +  IN      UINTN                     Address,
>>> +  IN      UINT64                    Value
>>> +  )
>>> +{
>>> +  ASSERT ((Address & 7) == 0);
>>> +
>>> +  MmioWrite64Internal (Address, Value);
>>> +  return Value;
>>> +}
>>> --
>>> 2.17.0
>>

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Re: [edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Posted by Gao, Liming, 2 weeks ago
Laszlo:
  I get your point. I am OK to add this library instance in MdePkg for code sharing. 

Ard:
  Have you plan to make this library instance pass VS2017 tool chain? 

Thanks
Liming
> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Friday, June 8, 2018 12:56 AM
> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Gao, Liming <liming.gao@intel.com>
> Cc: edk2-devel@lists.01.org; leif.lindholm@linaro.org; Kinney, Michael D <michael.d.kinney@intel.com>
> Subject: Re: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
> 
> On 06/07/18 17:09, Ard Biesheuvel wrote:
> > On 7 June 2018 at 17:08, Gao, Liming <liming.gao@intel.com> wrote:
> >> Ard:
> >>   If this library instance is specific to ARM emulator with KVM, how about add it into ArmVirtPkg?
> >>
> >
> > Laszlo, do you want to take this question?
> 
> Certainly.
> 
> Liming, in commit b6d11d7c4678, we added "BaseIoLibIntrinsicSev.inf" to
> "MdePkg/Library/BaseIoLibIntrinsic", with some custom Ia32 and X64 NASM
> files, but mostly reusing the large existent files ("IoLibMmioBuffer.c",
> "IoHighLevel.c" etc).
> 
> That library instance (and the NASM customizations) target AMD SEV; that
> is, when the code runs in a virtual machine for which AMD Secure
> Encrypted Virtualization is enabled. The NASM code uses CPUID to
> dynamically determine whether it runs in a SEV guest, or in a normal
> guest, and in the former case, it avoids using the REP prefix in the
> IoFifo routines (it uses open-coded LOOPs).
> 
> The "BaseIoLibIntrinsicSev.inf" instance is only ever used in OvmfPkg
> (it only makes sense in virtual machines), but the consensus back then
> was to add the lib instance to MdePkg.
> 
> 
> This time, Ard has already implemented (and posted) the IoLib instance
> that we need for ARM KVM such that it lands under ArmVirtPkg -- however,
> that library instance duplicates a huge amount of code, un-changed, from
> "BaseIoLibIntrinsic" (such as "IoLibMmioBuffer.c", "IoHighLevel.c"). I
> suggested that Ard instead post the new library instance as a new INF
> file (plus some assembly files) for BaseIoLibIntrinsic itself, because:
> (a) this way we avoid code duplication, and (b) that's exactly what we
> did -- for another virtualization-only use case -- in commit
> b6d11d7c4678 earlier.
> 
> If you'd like us to add the code to ArmVirtPkg, I don't think that's the
> right or consequent action, but technically, we can simply fall back to
> the ArmVirtPkg patches that Ard already wrote and posted.
> 
> Thanks,
> Laszlo
> 
> >>> -----Original Message-----
> >>> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> >>> Sent: Thursday, June 7, 2018 6:47 PM
> >>> To: edk2-devel@lists.01.org
> >>> Cc: lersek@redhat.com; leif.lindholm@linaro.org; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
> >>> <michael.d.kinney@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >>> Subject: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
> >>>
> >>> KVM on ARM refuses to decode load/store instructions used to perform
> >>> I/O to emulated devices, and instead relies on the exception syndrome
> >>> information to describe the operand register, access size, etc.
> >>> This is only possible for instructions that have a single input/output
> >>> register (as opposed to ones that increment the offset register, or
> >>> load/store pair instructions, etc). Otherwise, QEMU crashes with the
> >>> following error
> >>>
> >>>   error: kvm run failed Function not implemented
> >>>   R00=01010101 R01=00000008 R02=00000048 R03=08000820
> >>>   R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8
> >>>   R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080
> >>>   R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c
> >>>   PSR=800001f3 N--- T svc32
> >>>   QEMU: Terminated
> >>>
> >>> and KVM produces a warning such as the following in the kernel log
> >>>
> >>>   kvm [17646]: load/store instruction decoding not implemented
> >>>
> >>> The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic
> >>> is based on C code, and when LTO is in effect, the MMIO accesses could
> >>> be merged with, e.g., manipulations of the loop counter, producing
> >>> opcodes that KVM does not support for emulated MMIO.
> >>>
> >>> So let's add a special ArmVirt flavor of this library that implements
> >>> that actual load/store operations in assembler, ensuring that the
> >>> instructions involved can be emulated by KVM.
> >>>
> >>> Contributed-under: TianoCore Contribution Agreement 1.1
> >>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >>> ---
> >>>  ArmVirtPkg/ArmVirt.dsc.inc                                      |   2 +-
> >>>  MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S         | 164 +++++
> >>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S             | 161 +++++
> >>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm           | 165 +++++
> >>>  MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf |  50 ++
> >>>  MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c                | 641 ++++++++++++++++++++
> >>>  6 files changed, 1182 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/ArmVirtPkg/ArmVirt.dsc.inc b/ArmVirtPkg/ArmVirt.dsc.inc
> >>> index 766e4f598a07..7464ac70ed1b 100644
> >>> --- a/ArmVirtPkg/ArmVirt.dsc.inc
> >>> +++ b/ArmVirtPkg/ArmVirt.dsc.inc
> >>> @@ -41,7 +41,7 @@ [LibraryClasses.common]
> >>>    PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
> >>>    PeCoffGetEntryPointLib|MdePkg/Library/BasePeCoffGetEntryPointLib/BasePeCoffGetEntryPointLib.inf
> >>>    PeCoffLib|MdePkg/Library/BasePeCoffLib/BasePeCoffLib.inf
> >>> -  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
> >>> +  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
> >>>    UefiDecompressLib|MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.inf
> >>>    CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf
> >>>
> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
> b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
> >>> new file mode 100644
> >>> index 000000000000..47be68a3e783
> >>> --- /dev/null
> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
> >>> @@ -0,0 +1,164 @@
> >>> +#
> >>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
> >>> +#
> >>> +#  This program and the accompanying materials are licensed and made available
> >>> +#  under the terms and conditions of the BSD License which accompanies this
> >>> +#  distribution.  The full text of the license may be found at
> >>> +#  http://opensource.org/licenses/bsd-license.php
> >>> +#
> >>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >>> +#
> >>> +#
> >>> +
> >>> +.text
> >>> +.align 3
> >>> +
> >>> +GCC_ASM_EXPORT(MmioRead8Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite8Internal)
> >>> +GCC_ASM_EXPORT(MmioRead16Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite16Internal)
> >>> +GCC_ASM_EXPORT(MmioRead32Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite32Internal)
> >>> +GCC_ASM_EXPORT(MmioRead64Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite64Internal)
> >>> +
> >>> +//
> >>> +//  Reads an 8-bit MMIO register.
> >>> +//
> >>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead8Internal):
> >>> +  ldrb    w0, [x0]
> >>> +  dmb     ld
> >>> +  ret
> >>> +
> >>> +//
> >>> +//  Writes an 8-bit MMIO register.
> >>> +//
> >>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite8Internal):
> >>> +  dmb     st
> >>> +  strb    w1, [x0]
> >>> +  ret
> >>> +
> >>> +//
> >>> +//  Reads a 16-bit MMIO register.
> >>> +//
> >>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead16Internal):
> >>> +  ldrh    w0, [x0]
> >>> +  dmb     ld
> >>> +  ret
> >>> +
> >>> +//
> >>> +//  Writes a 16-bit MMIO register.
> >>> +//
> >>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite16Internal):
> >>> +  dmb     st
> >>> +  strh    w1, [x0]
> >>> +  ret
> >>> +
> >>> +//
> >>> +//  Reads a 32-bit MMIO register.
> >>> +//
> >>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead32Internal):
> >>> +  ldr     w0, [x0]
> >>> +  dmb     ld
> >>> +  ret
> >>> +
> >>> +//
> >>> +//  Writes a 32-bit MMIO register.
> >>> +//
> >>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite32Internal):
> >>> +  dmb     st
> >>> +  str     w1, [x0]
> >>> +  ret
> >>> +
> >>> +//
> >>> +//  Reads a 64-bit MMIO register.
> >>> +//
> >>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead64Internal):
> >>> +  ldr     x0, [x0]
> >>> +  dmb     ld
> >>> +  ret
> >>> +
> >>> +//
> >>> +//  Writes a 64-bit MMIO register.
> >>> +//
> >>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite64Internal):
> >>> +  dmb     st
> >>> +  str     x1, [x0]
> >>> +  ret
> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
> >>> new file mode 100644
> >>> index 000000000000..438805ca7c24
> >>> --- /dev/null
> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
> >>> @@ -0,0 +1,161 @@
> >>> +#
> >>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
> >>> +#
> >>> +#  This program and the accompanying materials are licensed and made available
> >>> +#  under the terms and conditions of the BSD License which accompanies this
> >>> +#  distribution.  The full text of the license may be found at
> >>> +#  http://opensource.org/licenses/bsd-license.php
> >>> +#
> >>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >>> +#
> >>> +#
> >>> +
> >>> +GCC_ASM_EXPORT(MmioRead8Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite8Internal)
> >>> +GCC_ASM_EXPORT(MmioRead16Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite16Internal)
> >>> +GCC_ASM_EXPORT(MmioRead32Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite32Internal)
> >>> +GCC_ASM_EXPORT(MmioRead64Internal)
> >>> +GCC_ASM_EXPORT(MmioWrite64Internal)
> >>> +
> >>> +//
> >>> +//  Reads an 8-bit MMIO register.
> >>> +//
> >>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead8Internal):
> >>> +  ldrb    r0, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +//
> >>> +//  Writes an 8-bit MMIO register.
> >>> +//
> >>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite8Internal):
> >>> +  dmb     st
> >>> +  strb    r1, [r0]
> >>> +  bx      lr
> >>> +
> >>> +//
> >>> +//  Reads a 16-bit MMIO register.
> >>> +//
> >>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead16Internal):
> >>> +  ldrh    r0, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +//
> >>> +//  Writes a 16-bit MMIO register.
> >>> +//
> >>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite16Internal):
> >>> +  dmb     st
> >>> +  strh    r1, [r0]
> >>> +  bx      lr
> >>> +
> >>> +//
> >>> +//  Reads a 32-bit MMIO register.
> >>> +//
> >>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead32Internal):
> >>> +  ldr     r0, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +//
> >>> +//  Writes a 32-bit MMIO register.
> >>> +//
> >>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite32Internal):
> >>> +  dmb     st
> >>> +  str     r1, [r0]
> >>> +  bx      lr
> >>> +
> >>> +//
> >>> +//  Reads a 64-bit MMIO register.
> >>> +//
> >>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> >>> +//  returned. This function must guarantee that all MMIO read and write
> >>> +//  operations are serialized.
> >>> +//
> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to read.
> >>> +//
> >>> +//  @return The value read.
> >>> +//
> >>> +ASM_PFX(MmioRead64Internal):
> >>> +  ldrd    r0, r1, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +//
> >>> +//  Writes a 64-bit MMIO register.
> >>> +//
> >>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +//  and write operations are serialized.
> >>> +//
> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +//
> >>> +//  @param  Address The MMIO register to write.
> >>> +//  @param  Value   The value to write to the MMIO register.
> >>> +//
> >>> +ASM_PFX(MmioWrite64Internal):
> >>> +  dmb     st
> >>> +  strd    r2, r3, [r0]
> >>> +  bx      lr
> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
> b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
> >>> new file mode 100644
> >>> index 000000000000..82add82f800a
> >>> --- /dev/null
> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
> >>> @@ -0,0 +1,165 @@
> >>> +;
> >>> +;  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
> >>> +;
> >>> +;  This program and the accompanying materials are licensed and made available
> >>> +;  under the terms and conditions of the BSD License which accompanies this
> >>> +;  distribution.  The full text of the license may be found at
> >>> +;  http:;opensource.org/licenses/bsd-license.php
> >>> +;
> >>> +;  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >>> +;  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >>> +;
> >>> +
> >>> +
> >>> +AREA IoLibMmio, CODE, READONLY
> >>> +
> >>> +EXPORT MmioRead8Internal
> >>> +EXPORT MmioWrite8Internal
> >>> +EXPORT MmioRead16Internal
> >>> +EXPORT MmioWrite16Internal
> >>> +EXPORT MmioRead32Internal
> >>> +EXPORT MmioWrite32Internal
> >>> +EXPORT MmioRead64Internal
> >>> +EXPORT MmioWrite64Internal
> >>> +
> >>> +;
> >>> +;  Reads an 8-bit MMIO register.
> >>> +;
> >>> +;  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> >>> +;  returned. This function must guarantee that all MMIO read and write
> >>> +;  operations are serialized.
> >>> +;
> >>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to read.
> >>> +;
> >>> +;  @return The value read.
> >>> +;
> >>> +MmioRead8Internal
> >>> +  ldrb    r0, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +;
> >>> +;  Writes an 8-bit MMIO register.
> >>> +;
> >>> +;  Writes the 8-bit MMIO register specified by Address with the value specified
> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +;  and write operations are serialized.
> >>> +;
> >>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to write.
> >>> +;  @param  Value   The value to write to the MMIO register.
> >>> +;
> >>> +MmioWrite8Internal
> >>> +  dmb     st
> >>> +  strb    r1, [r0]
> >>> +  bx      lr
> >>> +
> >>> +;
> >>> +;  Reads a 16-bit MMIO register.
> >>> +;
> >>> +;  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> >>> +;  returned. This function must guarantee that all MMIO read and write
> >>> +;  operations are serialized.
> >>> +;
> >>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to read.
> >>> +;
> >>> +;  @return The value read.
> >>> +;
> >>> +MmioRead16Internal
> >>> +  ldrh    r0, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +;
> >>> +;  Writes a 16-bit MMIO register.
> >>> +;
> >>> +;  Writes the 16-bit MMIO register specified by Address with the value specified
> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +;  and write operations are serialized.
> >>> +;
> >>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to write.
> >>> +;  @param  Value   The value to write to the MMIO register.
> >>> +;
> >>> +MmioWrite16Internal
> >>> +  dmb     st
> >>> +  strh    r1, [r0]
> >>> +  bx      lr
> >>> +
> >>> +;
> >>> +;  Reads a 32-bit MMIO register.
> >>> +;
> >>> +;  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> >>> +;  returned. This function must guarantee that all MMIO read and write
> >>> +;  operations are serialized.
> >>> +;
> >>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to read.
> >>> +;
> >>> +;  @return The value read.
> >>> +;
> >>> +MmioRead32Internal
> >>> +  ldr     r0, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +;
> >>> +;  Writes a 32-bit MMIO register.
> >>> +;
> >>> +;  Writes the 32-bit MMIO register specified by Address with the value specified
> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +;  and write operations are serialized.
> >>> +;
> >>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to write.
> >>> +;  @param  Value   The value to write to the MMIO register.
> >>> +;
> >>> +MmioWrite32Internal
> >>> +  dmb     st
> >>> +  str     r1, [r0]
> >>> +  bx      lr
> >>> +
> >>> +;
> >>> +;  Reads a 64-bit MMIO register.
> >>> +;
> >>> +;  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> >>> +;  returned. This function must guarantee that all MMIO read and write
> >>> +;  operations are serialized.
> >>> +;
> >>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to read.
> >>> +;
> >>> +;  @return The value read.
> >>> +;
> >>> +MmioRead64Internal
> >>> +  ldrd    r0, r1, [r0]
> >>> +  dmb
> >>> +  bx      lr
> >>> +
> >>> +;
> >>> +;  Writes a 64-bit MMIO register.
> >>> +;
> >>> +;  Writes the 64-bit MMIO register specified by Address with the value specified
> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +;  and write operations are serialized.
> >>> +;
> >>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +;
> >>> +;  @param  Address The MMIO register to write.
> >>> +;  @param  Value   The value to write to the MMIO register.
> >>> +;
> >>> +MmioWrite64Internal
> >>> +  dmb     st
> >>> +  strd    r2, r3, [r0]
> >>> +  bx      lr
> >>> +
> >>> +  END
> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
> >>> b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
> >>> new file mode 100644
> >>> index 000000000000..5a1dc87ed2bd
> >>> --- /dev/null
> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
> >>> @@ -0,0 +1,50 @@
> >>> +## @file
> >>> +#  Instance of I/O Library using KVM/ARM safe assembler routines
> >>> +#
> >>> +#  Copyright (c) 2007 - 2015, Intel Corporation. All rights reserved.<BR>
> >>> +#  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
> >>> +#  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
> >>> +#  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
> >>> +#
> >>> +#  This program and the accompanying materials are licensed and made available
> >>> +#  under the terms and conditions of the BSD License which accompanies this
> >>> +#  distribution. The full text of the license may be found at
> >>> +#  http://opensource.org/licenses/bsd-license.php.
> >>> +#
> >>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >>> +#
> >>> +##
> >>> +
> >>> +[Defines]
> >>> +  INF_VERSION                    = 0x0001001A
> >>> +  BASE_NAME                      = BaseIoLibIntrinsicArmVirt
> >>> +  FILE_GUID                      = 217102b4-b465-4a1d-a2de-93dd385ec480
> >>> +  MODULE_TYPE                    = BASE
> >>> +  VERSION_STRING                 = 1.0
> >>> +  LIBRARY_CLASS                  = IoLib
> >>> +
> >>> +#
> >>> +#  VALID_ARCHITECTURES           = ARM AARCH64
> >>> +#
> >>> +
> >>> +[Sources]
> >>> +  IoLibMmioBuffer.c
> >>> +  BaseIoLibIntrinsicInternal.h
> >>> +  IoHighLevel.c
> >>> +
> >>> +[Sources.ARM]
> >>> +  IoLibArmVirt.c
> >>> +  Arm/ArmVirtMmio.S   | GCC
> >>> +  Arm/ArmVirtMmio.asm | RVCT
> >>> +
> >>> +[Sources.AARCH64]
> >>> +  IoLibArmVirt.c
> >>> +  AArch64/ArmVirtMmio.S
> >>> +
> >>> +[Packages]
> >>> +  MdePkg/MdePkg.dec
> >>> +
> >>> +[LibraryClasses]
> >>> +  DebugLib
> >>> +  BaseLib
> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
> >>> new file mode 100644
> >>> index 000000000000..154d583246ac
> >>> --- /dev/null
> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
> >>> @@ -0,0 +1,641 @@
> >>> +/** @file
> >>> +  I/O Library for ARM.
> >>> +
> >>> +  Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
> >>> +  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
> >>> +  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
> >>> +  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
> >>> +
> >>> +  This program and the accompanying materials are licensed and made available
> >>> +  under the terms and conditions of the BSD License which accompanies this
> >>> +  distribution. The full text of the license may be found at
> >>> +  http://opensource.org/licenses/bsd-license.php.
> >>> +
> >>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
> >>> +  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
> >>> +
> >>> +**/
> >>> +
> >>> +#include "BaseIoLibIntrinsicInternal.h"
> >>> +
> >>> +UINT8
> >>> +EFIAPI
> >>> +MmioRead8Internal (
> >>> +  IN      UINTN                     Address
> >>> +  );
> >>> +
> >>> +VOID
> >>> +EFIAPI
> >>> +MmioWrite8Internal (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT8                     Value
> >>> +  );
> >>> +
> >>> +UINT16
> >>> +EFIAPI
> >>> +MmioRead16Internal (
> >>> +  IN      UINTN                     Address
> >>> +  );
> >>> +
> >>> +VOID
> >>> +EFIAPI
> >>> +MmioWrite16Internal (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT16                    Value
> >>> +  );
> >>> +
> >>> +UINT32
> >>> +EFIAPI
> >>> +MmioRead32Internal (
> >>> +  IN      UINTN                     Address
> >>> +  );
> >>> +
> >>> +VOID
> >>> +EFIAPI
> >>> +MmioWrite32Internal (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT32                    Value
> >>> +  );
> >>> +
> >>> +UINT64
> >>> +EFIAPI
> >>> +MmioRead64Internal (
> >>> +  IN      UINTN                     Address
> >>> +  );
> >>> +
> >>> +VOID
> >>> +EFIAPI
> >>> +MmioWrite64Internal (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT64                    Value
> >>> +  );
> >>> +
> >>> +/**
> >>> +  Reads an 8-bit I/O port.
> >>> +
> >>> +  Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
> >>> +  This function must guarantee that all I/O read and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT8
> >>> +EFIAPI
> >>> +IoRead8 (
> >>> +  IN      UINTN                     Port
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return 0;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes an 8-bit I/O port.
> >>> +
> >>> +  Writes the 8-bit I/O port specified by Port with the value specified by Value
> >>> +  and returns Value. This function must guarantee that all I/O read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to write.
> >>> +  @param  Value The value to write to the I/O port.
> >>> +
> >>> +  @return The value written the I/O port.
> >>> +
> >>> +**/
> >>> +UINT8
> >>> +EFIAPI
> >>> +IoWrite8 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINT8                     Value
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return Value;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 16-bit I/O port.
> >>> +
> >>> +  Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
> >>> +  This function must guarantee that all I/O read and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT16
> >>> +EFIAPI
> >>> +IoRead16 (
> >>> +  IN      UINTN                     Port
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return 0;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a 16-bit I/O port.
> >>> +
> >>> +  Writes the 16-bit I/O port specified by Port with the value specified by Value
> >>> +  and returns Value. This function must guarantee that all I/O read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to write.
> >>> +  @param  Value The value to write to the I/O port.
> >>> +
> >>> +  @return The value written the I/O port.
> >>> +
> >>> +**/
> >>> +UINT16
> >>> +EFIAPI
> >>> +IoWrite16 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINT16                    Value
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return Value;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 32-bit I/O port.
> >>> +
> >>> +  Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
> >>> +  This function must guarantee that all I/O read and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT32
> >>> +EFIAPI
> >>> +IoRead32 (
> >>> +  IN      UINTN                     Port
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return 0;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a 32-bit I/O port.
> >>> +
> >>> +  Writes the 32-bit I/O port specified by Port with the value specified by Value
> >>> +  and returns Value. This function must guarantee that all I/O read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to write.
> >>> +  @param  Value The value to write to the I/O port.
> >>> +
> >>> +  @return The value written the I/O port.
> >>> +
> >>> +**/
> >>> +UINT32
> >>> +EFIAPI
> >>> +IoWrite32 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINT32                    Value
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return Value;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 64-bit I/O port.
> >>> +
> >>> +  Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
> >>> +  This function must guarantee that all I/O read and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 64-bit I/O port operations are not supported, then ASSERT().
> >>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT64
> >>> +EFIAPI
> >>> +IoRead64 (
> >>> +  IN      UINTN                     Port
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return 0;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a 64-bit I/O port.
> >>> +
> >>> +  Writes the 64-bit I/O port specified by Port with the value specified by Value
> >>> +  and returns Value. This function must guarantee that all I/O read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 64-bit I/O port operations are not supported, then ASSERT().
> >>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
> >>> +
> >>> +  @param  Port  The I/O port to write.
> >>> +  @param  Value The value to write to the I/O port.
> >>> +
> >>> +  @return The value written to the I/O port.
> >>> +
> >>> +**/
> >>> +UINT64
> >>> +EFIAPI
> >>> +IoWrite64 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINT64                    Value
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +  return 0;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads an 8-bit I/O port fifo into a block of memory.
> >>> +
> >>> +  Reads the 8-bit I/O fifo port specified by Port.
> >>> +  The port is read Count times, and the read data is
> >>> +  stored in the provided Buffer.
> >>> +
> >>> +  This function must guarantee that all I/O read and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port    The I/O port to read.
> >>> +  @param  Count   The number of times to read I/O port.
> >>> +  @param  Buffer  The buffer to store the read data into.
> >>> +
> >>> +**/
> >>> +VOID
> >>> +EFIAPI
> >>> +IoReadFifo8 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINTN                     Count,
> >>> +  OUT     VOID                      *Buffer
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a block of memory into an 8-bit I/O port fifo.
> >>> +
> >>> +  Writes the 8-bit I/O fifo port specified by Port.
> >>> +  The port is written Count times, and the write data is
> >>> +  retrieved from the provided Buffer.
> >>> +
> >>> +  This function must guarantee that all I/O write and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port    The I/O port to write.
> >>> +  @param  Count   The number of times to write I/O port.
> >>> +  @param  Buffer  The buffer to retrieve the write data from.
> >>> +
> >>> +**/
> >>> +VOID
> >>> +EFIAPI
> >>> +IoWriteFifo8 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINTN                     Count,
> >>> +  IN      VOID                      *Buffer
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 16-bit I/O port fifo into a block of memory.
> >>> +
> >>> +  Reads the 16-bit I/O fifo port specified by Port.
> >>> +  The port is read Count times, and the read data is
> >>> +  stored in the provided Buffer.
> >>> +
> >>> +  This function must guarantee that all I/O read and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port    The I/O port to read.
> >>> +  @param  Count   The number of times to read I/O port.
> >>> +  @param  Buffer  The buffer to store the read data into.
> >>> +
> >>> +**/
> >>> +VOID
> >>> +EFIAPI
> >>> +IoReadFifo16 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINTN                     Count,
> >>> +  OUT     VOID                      *Buffer
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a block of memory into a 16-bit I/O port fifo.
> >>> +
> >>> +  Writes the 16-bit I/O fifo port specified by Port.
> >>> +  The port is written Count times, and the write data is
> >>> +  retrieved from the provided Buffer.
> >>> +
> >>> +  This function must guarantee that all I/O write and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port    The I/O port to write.
> >>> +  @param  Count   The number of times to write I/O port.
> >>> +  @param  Buffer  The buffer to retrieve the write data from.
> >>> +
> >>> +**/
> >>> +VOID
> >>> +EFIAPI
> >>> +IoWriteFifo16 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINTN                     Count,
> >>> +  IN      VOID                      *Buffer
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 32-bit I/O port fifo into a block of memory.
> >>> +
> >>> +  Reads the 32-bit I/O fifo port specified by Port.
> >>> +  The port is read Count times, and the read data is
> >>> +  stored in the provided Buffer.
> >>> +
> >>> +  This function must guarantee that all I/O read and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port    The I/O port to read.
> >>> +  @param  Count   The number of times to read I/O port.
> >>> +  @param  Buffer  The buffer to store the read data into.
> >>> +
> >>> +**/
> >>> +VOID
> >>> +EFIAPI
> >>> +IoReadFifo32 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINTN                     Count,
> >>> +  OUT     VOID                      *Buffer
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a block of memory into a 32-bit I/O port fifo.
> >>> +
> >>> +  Writes the 32-bit I/O fifo port specified by Port.
> >>> +  The port is written Count times, and the write data is
> >>> +  retrieved from the provided Buffer.
> >>> +
> >>> +  This function must guarantee that all I/O write and write operations are
> >>> +  serialized.
> >>> +
> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Port    The I/O port to write.
> >>> +  @param  Count   The number of times to write I/O port.
> >>> +  @param  Buffer  The buffer to retrieve the write data from.
> >>> +
> >>> +**/
> >>> +VOID
> >>> +EFIAPI
> >>> +IoWriteFifo32 (
> >>> +  IN      UINTN                     Port,
> >>> +  IN      UINTN                     Count,
> >>> +  IN      VOID                      *Buffer
> >>> +  )
> >>> +{
> >>> +  ASSERT (FALSE);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads an 8-bit MMIO register.
> >>> +
> >>> +  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
> >>> +  returned. This function must guarantee that all MMIO read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT8
> >>> +EFIAPI
> >>> +MmioRead8 (
> >>> +  IN      UINTN                     Address
> >>> +  )
> >>> +{
> >>> +  return MmioRead8Internal (Address);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes an 8-bit MMIO register.
> >>> +
> >>> +  Writes the 8-bit MMIO register specified by Address with the value specified
> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +  and write operations are serialized.
> >>> +
> >>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to write.
> >>> +  @param  Value   The value to write to the MMIO register.
> >>> +
> >>> +**/
> >>> +UINT8
> >>> +EFIAPI
> >>> +MmioWrite8 (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT8                     Value
> >>> +  )
> >>> +{
> >>> +  MmioWrite8Internal (Address, Value);
> >>> +  return Value;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 16-bit MMIO register.
> >>> +
> >>> +  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
> >>> +  returned. This function must guarantee that all MMIO read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT16
> >>> +EFIAPI
> >>> +MmioRead16 (
> >>> +  IN      UINTN                     Address
> >>> +  )
> >>> +{
> >>> +  ASSERT ((Address & 1) == 0);
> >>> +
> >>> +  return MmioRead16Internal (Address);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a 16-bit MMIO register.
> >>> +
> >>> +  Writes the 16-bit MMIO register specified by Address with the value specified
> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +  and write operations are serialized.
> >>> +
> >>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to write.
> >>> +  @param  Value   The value to write to the MMIO register.
> >>> +
> >>> +**/
> >>> +UINT16
> >>> +EFIAPI
> >>> +MmioWrite16 (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT16                    Value
> >>> +  )
> >>> +{
> >>> +  ASSERT ((Address & 1) == 0);
> >>> +
> >>> +  MmioWrite16Internal (Address, Value);
> >>> +  return Value;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 32-bit MMIO register.
> >>> +
> >>> +  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
> >>> +  returned. This function must guarantee that all MMIO read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT32
> >>> +EFIAPI
> >>> +MmioRead32 (
> >>> +  IN      UINTN                     Address
> >>> +  )
> >>> +{
> >>> +  ASSERT ((Address & 3) == 0);
> >>> +
> >>> +  return MmioRead32Internal (Address);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a 32-bit MMIO register.
> >>> +
> >>> +  Writes the 32-bit MMIO register specified by Address with the value specified
> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +  and write operations are serialized.
> >>> +
> >>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to write.
> >>> +  @param  Value   The value to write to the MMIO register.
> >>> +
> >>> +**/
> >>> +UINT32
> >>> +EFIAPI
> >>> +MmioWrite32 (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT32                    Value
> >>> +  )
> >>> +{
> >>> +  ASSERT ((Address & 3) == 0);
> >>> +
> >>> +  MmioWrite32Internal (Address, Value);
> >>> +  return Value;
> >>> +}
> >>> +
> >>> +/**
> >>> +  Reads a 64-bit MMIO register.
> >>> +
> >>> +  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
> >>> +  returned. This function must guarantee that all MMIO read and write
> >>> +  operations are serialized.
> >>> +
> >>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to read.
> >>> +
> >>> +  @return The value read.
> >>> +
> >>> +**/
> >>> +UINT64
> >>> +EFIAPI
> >>> +MmioRead64 (
> >>> +  IN      UINTN                     Address
> >>> +  )
> >>> +{
> >>> +  ASSERT ((Address & 7) == 0);
> >>> +
> >>> +  return MmioRead64Internal (Address);
> >>> +}
> >>> +
> >>> +/**
> >>> +  Writes a 64-bit MMIO register.
> >>> +
> >>> +  Writes the 64-bit MMIO register specified by Address with the value specified
> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
> >>> +  and write operations are serialized.
> >>> +
> >>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
> >>> +
> >>> +  @param  Address The MMIO register to write.
> >>> +  @param  Value   The value to write to the MMIO register.
> >>> +
> >>> +**/
> >>> +UINT64
> >>> +EFIAPI
> >>> +MmioWrite64 (
> >>> +  IN      UINTN                     Address,
> >>> +  IN      UINT64                    Value
> >>> +  )
> >>> +{
> >>> +  ASSERT ((Address & 7) == 0);
> >>> +
> >>> +  MmioWrite64Internal (Address, Value);
> >>> +  return Value;
> >>> +}
> >>> --
> >>> 2.17.0
> >>

_______________________________________________
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Re: [edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Posted by Ard Biesheuvel, 2 weeks ago
On 8 June 2018 at 18:38, Gao, Liming <liming.gao@intel.com> wrote:
> Laszlo:
>   I get your point. I am OK to add this library instance in MdePkg for code sharing.
>
> Ard:
>   Have you plan to make this library instance pass VS2017 tool chain?
>

Good point. I will add that.

> Thanks
> Liming
>> -----Original Message-----
>> From: Laszlo Ersek [mailto:lersek@redhat.com]
>> Sent: Friday, June 8, 2018 12:56 AM
>> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Gao, Liming <liming.gao@intel.com>
>> Cc: edk2-devel@lists.01.org; leif.lindholm@linaro.org; Kinney, Michael D <michael.d.kinney@intel.com>
>> Subject: Re: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
>>
>> On 06/07/18 17:09, Ard Biesheuvel wrote:
>> > On 7 June 2018 at 17:08, Gao, Liming <liming.gao@intel.com> wrote:
>> >> Ard:
>> >>   If this library instance is specific to ARM emulator with KVM, how about add it into ArmVirtPkg?
>> >>
>> >
>> > Laszlo, do you want to take this question?
>>
>> Certainly.
>>
>> Liming, in commit b6d11d7c4678, we added "BaseIoLibIntrinsicSev.inf" to
>> "MdePkg/Library/BaseIoLibIntrinsic", with some custom Ia32 and X64 NASM
>> files, but mostly reusing the large existent files ("IoLibMmioBuffer.c",
>> "IoHighLevel.c" etc).
>>
>> That library instance (and the NASM customizations) target AMD SEV; that
>> is, when the code runs in a virtual machine for which AMD Secure
>> Encrypted Virtualization is enabled. The NASM code uses CPUID to
>> dynamically determine whether it runs in a SEV guest, or in a normal
>> guest, and in the former case, it avoids using the REP prefix in the
>> IoFifo routines (it uses open-coded LOOPs).
>>
>> The "BaseIoLibIntrinsicSev.inf" instance is only ever used in OvmfPkg
>> (it only makes sense in virtual machines), but the consensus back then
>> was to add the lib instance to MdePkg.
>>
>>
>> This time, Ard has already implemented (and posted) the IoLib instance
>> that we need for ARM KVM such that it lands under ArmVirtPkg -- however,
>> that library instance duplicates a huge amount of code, un-changed, from
>> "BaseIoLibIntrinsic" (such as "IoLibMmioBuffer.c", "IoHighLevel.c"). I
>> suggested that Ard instead post the new library instance as a new INF
>> file (plus some assembly files) for BaseIoLibIntrinsic itself, because:
>> (a) this way we avoid code duplication, and (b) that's exactly what we
>> did -- for another virtualization-only use case -- in commit
>> b6d11d7c4678 earlier.
>>
>> If you'd like us to add the code to ArmVirtPkg, I don't think that's the
>> right or consequent action, but technically, we can simply fall back to
>> the ArmVirtPkg patches that Ard already wrote and posted.
>>
>> Thanks,
>> Laszlo
>>
>> >>> -----Original Message-----
>> >>> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>> >>> Sent: Thursday, June 7, 2018 6:47 PM
>> >>> To: edk2-devel@lists.01.org
>> >>> Cc: lersek@redhat.com; leif.lindholm@linaro.org; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
>> >>> <michael.d.kinney@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> >>> Subject: [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
>> >>>
>> >>> KVM on ARM refuses to decode load/store instructions used to perform
>> >>> I/O to emulated devices, and instead relies on the exception syndrome
>> >>> information to describe the operand register, access size, etc.
>> >>> This is only possible for instructions that have a single input/output
>> >>> register (as opposed to ones that increment the offset register, or
>> >>> load/store pair instructions, etc). Otherwise, QEMU crashes with the
>> >>> following error
>> >>>
>> >>>   error: kvm run failed Function not implemented
>> >>>   R00=01010101 R01=00000008 R02=00000048 R03=08000820
>> >>>   R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8
>> >>>   R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080
>> >>>   R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c
>> >>>   PSR=800001f3 N--- T svc32
>> >>>   QEMU: Terminated
>> >>>
>> >>> and KVM produces a warning such as the following in the kernel log
>> >>>
>> >>>   kvm [17646]: load/store instruction decoding not implemented
>> >>>
>> >>> The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic
>> >>> is based on C code, and when LTO is in effect, the MMIO accesses could
>> >>> be merged with, e.g., manipulations of the loop counter, producing
>> >>> opcodes that KVM does not support for emulated MMIO.
>> >>>
>> >>> So let's add a special ArmVirt flavor of this library that implements
>> >>> that actual load/store operations in assembler, ensuring that the
>> >>> instructions involved can be emulated by KVM.
>> >>>
>> >>> Contributed-under: TianoCore Contribution Agreement 1.1
>> >>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> >>> ---
>> >>>  ArmVirtPkg/ArmVirt.dsc.inc                                      |   2 +-
>> >>>  MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S         | 164 +++++
>> >>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S             | 161 +++++
>> >>>  MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm           | 165 +++++
>> >>>  MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf |  50 ++
>> >>>  MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c                | 641 ++++++++++++++++++++
>> >>>  6 files changed, 1182 insertions(+), 1 deletion(-)
>> >>>
>> >>> diff --git a/ArmVirtPkg/ArmVirt.dsc.inc b/ArmVirtPkg/ArmVirt.dsc.inc
>> >>> index 766e4f598a07..7464ac70ed1b 100644
>> >>> --- a/ArmVirtPkg/ArmVirt.dsc.inc
>> >>> +++ b/ArmVirtPkg/ArmVirt.dsc.inc
>> >>> @@ -41,7 +41,7 @@ [LibraryClasses.common]
>> >>>    PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
>> >>>    PeCoffGetEntryPointLib|MdePkg/Library/BasePeCoffGetEntryPointLib/BasePeCoffGetEntryPointLib.inf
>> >>>    PeCoffLib|MdePkg/Library/BasePeCoffLib/BasePeCoffLib.inf
>> >>> -  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>> >>> +  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>> >>>    UefiDecompressLib|MdePkg/Library/BaseUefiDecompressLib/BaseUefiDecompressLib.inf
>> >>>    CpuLib|MdePkg/Library/BaseCpuLib/BaseCpuLib.inf
>> >>>
>> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
>> b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
>> >>> new file mode 100644
>> >>> index 000000000000..47be68a3e783
>> >>> --- /dev/null
>> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/AArch64/ArmVirtMmio.S
>> >>> @@ -0,0 +1,164 @@
>> >>> +#
>> >>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>> >>> +#
>> >>> +#  This program and the accompanying materials are licensed and made available
>> >>> +#  under the terms and conditions of the BSD License which accompanies this
>> >>> +#  distribution.  The full text of the license may be found at
>> >>> +#  http://opensource.org/licenses/bsd-license.php
>> >>> +#
>> >>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> >>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> >>> +#
>> >>> +#
>> >>> +
>> >>> +.text
>> >>> +.align 3
>> >>> +
>> >>> +GCC_ASM_EXPORT(MmioRead8Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite8Internal)
>> >>> +GCC_ASM_EXPORT(MmioRead16Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite16Internal)
>> >>> +GCC_ASM_EXPORT(MmioRead32Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite32Internal)
>> >>> +GCC_ASM_EXPORT(MmioRead64Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite64Internal)
>> >>> +
>> >>> +//
>> >>> +//  Reads an 8-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead8Internal):
>> >>> +  ldrb    w0, [x0]
>> >>> +  dmb     ld
>> >>> +  ret
>> >>> +
>> >>> +//
>> >>> +//  Writes an 8-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite8Internal):
>> >>> +  dmb     st
>> >>> +  strb    w1, [x0]
>> >>> +  ret
>> >>> +
>> >>> +//
>> >>> +//  Reads a 16-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead16Internal):
>> >>> +  ldrh    w0, [x0]
>> >>> +  dmb     ld
>> >>> +  ret
>> >>> +
>> >>> +//
>> >>> +//  Writes a 16-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite16Internal):
>> >>> +  dmb     st
>> >>> +  strh    w1, [x0]
>> >>> +  ret
>> >>> +
>> >>> +//
>> >>> +//  Reads a 32-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead32Internal):
>> >>> +  ldr     w0, [x0]
>> >>> +  dmb     ld
>> >>> +  ret
>> >>> +
>> >>> +//
>> >>> +//  Writes a 32-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite32Internal):
>> >>> +  dmb     st
>> >>> +  str     w1, [x0]
>> >>> +  ret
>> >>> +
>> >>> +//
>> >>> +//  Reads a 64-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead64Internal):
>> >>> +  ldr     x0, [x0]
>> >>> +  dmb     ld
>> >>> +  ret
>> >>> +
>> >>> +//
>> >>> +//  Writes a 64-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite64Internal):
>> >>> +  dmb     st
>> >>> +  str     x1, [x0]
>> >>> +  ret
>> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
>> >>> new file mode 100644
>> >>> index 000000000000..438805ca7c24
>> >>> --- /dev/null
>> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S
>> >>> @@ -0,0 +1,161 @@
>> >>> +#
>> >>> +#  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>> >>> +#
>> >>> +#  This program and the accompanying materials are licensed and made available
>> >>> +#  under the terms and conditions of the BSD License which accompanies this
>> >>> +#  distribution.  The full text of the license may be found at
>> >>> +#  http://opensource.org/licenses/bsd-license.php
>> >>> +#
>> >>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> >>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> >>> +#
>> >>> +#
>> >>> +
>> >>> +GCC_ASM_EXPORT(MmioRead8Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite8Internal)
>> >>> +GCC_ASM_EXPORT(MmioRead16Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite16Internal)
>> >>> +GCC_ASM_EXPORT(MmioRead32Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite32Internal)
>> >>> +GCC_ASM_EXPORT(MmioRead64Internal)
>> >>> +GCC_ASM_EXPORT(MmioWrite64Internal)
>> >>> +
>> >>> +//
>> >>> +//  Reads an 8-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead8Internal):
>> >>> +  ldrb    r0, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +//
>> >>> +//  Writes an 8-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 8-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite8Internal):
>> >>> +  dmb     st
>> >>> +  strb    r1, [r0]
>> >>> +  bx      lr
>> >>> +
>> >>> +//
>> >>> +//  Reads a 16-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead16Internal):
>> >>> +  ldrh    r0, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +//
>> >>> +//  Writes a 16-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 16-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite16Internal):
>> >>> +  dmb     st
>> >>> +  strh    r1, [r0]
>> >>> +  bx      lr
>> >>> +
>> >>> +//
>> >>> +//  Reads a 32-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead32Internal):
>> >>> +  ldr     r0, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +//
>> >>> +//  Writes a 32-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 32-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite32Internal):
>> >>> +  dmb     st
>> >>> +  str     r1, [r0]
>> >>> +  bx      lr
>> >>> +
>> >>> +//
>> >>> +//  Reads a 64-bit MMIO register.
>> >>> +//
>> >>> +//  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> >>> +//  returned. This function must guarantee that all MMIO read and write
>> >>> +//  operations are serialized.
>> >>> +//
>> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to read.
>> >>> +//
>> >>> +//  @return The value read.
>> >>> +//
>> >>> +ASM_PFX(MmioRead64Internal):
>> >>> +  ldrd    r0, r1, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +//
>> >>> +//  Writes a 64-bit MMIO register.
>> >>> +//
>> >>> +//  Writes the 64-bit MMIO register specified by Address with the value specified
>> >>> +//  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +//  and write operations are serialized.
>> >>> +//
>> >>> +//  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +//
>> >>> +//  @param  Address The MMIO register to write.
>> >>> +//  @param  Value   The value to write to the MMIO register.
>> >>> +//
>> >>> +ASM_PFX(MmioWrite64Internal):
>> >>> +  dmb     st
>> >>> +  strd    r2, r3, [r0]
>> >>> +  bx      lr
>> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
>> b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
>> >>> new file mode 100644
>> >>> index 000000000000..82add82f800a
>> >>> --- /dev/null
>> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm
>> >>> @@ -0,0 +1,165 @@
>> >>> +;
>> >>> +;  Copyright (c) 2014-2018, Linaro Limited. All rights reserved.
>> >>> +;
>> >>> +;  This program and the accompanying materials are licensed and made available
>> >>> +;  under the terms and conditions of the BSD License which accompanies this
>> >>> +;  distribution.  The full text of the license may be found at
>> >>> +;  http:;opensource.org/licenses/bsd-license.php
>> >>> +;
>> >>> +;  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> >>> +;  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> >>> +;
>> >>> +
>> >>> +
>> >>> +AREA IoLibMmio, CODE, READONLY
>> >>> +
>> >>> +EXPORT MmioRead8Internal
>> >>> +EXPORT MmioWrite8Internal
>> >>> +EXPORT MmioRead16Internal
>> >>> +EXPORT MmioWrite16Internal
>> >>> +EXPORT MmioRead32Internal
>> >>> +EXPORT MmioWrite32Internal
>> >>> +EXPORT MmioRead64Internal
>> >>> +EXPORT MmioWrite64Internal
>> >>> +
>> >>> +;
>> >>> +;  Reads an 8-bit MMIO register.
>> >>> +;
>> >>> +;  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> >>> +;  returned. This function must guarantee that all MMIO read and write
>> >>> +;  operations are serialized.
>> >>> +;
>> >>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to read.
>> >>> +;
>> >>> +;  @return The value read.
>> >>> +;
>> >>> +MmioRead8Internal
>> >>> +  ldrb    r0, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +;
>> >>> +;  Writes an 8-bit MMIO register.
>> >>> +;
>> >>> +;  Writes the 8-bit MMIO register specified by Address with the value specified
>> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +;  and write operations are serialized.
>> >>> +;
>> >>> +;  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to write.
>> >>> +;  @param  Value   The value to write to the MMIO register.
>> >>> +;
>> >>> +MmioWrite8Internal
>> >>> +  dmb     st
>> >>> +  strb    r1, [r0]
>> >>> +  bx      lr
>> >>> +
>> >>> +;
>> >>> +;  Reads a 16-bit MMIO register.
>> >>> +;
>> >>> +;  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> >>> +;  returned. This function must guarantee that all MMIO read and write
>> >>> +;  operations are serialized.
>> >>> +;
>> >>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to read.
>> >>> +;
>> >>> +;  @return The value read.
>> >>> +;
>> >>> +MmioRead16Internal
>> >>> +  ldrh    r0, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +;
>> >>> +;  Writes a 16-bit MMIO register.
>> >>> +;
>> >>> +;  Writes the 16-bit MMIO register specified by Address with the value specified
>> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +;  and write operations are serialized.
>> >>> +;
>> >>> +;  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to write.
>> >>> +;  @param  Value   The value to write to the MMIO register.
>> >>> +;
>> >>> +MmioWrite16Internal
>> >>> +  dmb     st
>> >>> +  strh    r1, [r0]
>> >>> +  bx      lr
>> >>> +
>> >>> +;
>> >>> +;  Reads a 32-bit MMIO register.
>> >>> +;
>> >>> +;  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> >>> +;  returned. This function must guarantee that all MMIO read and write
>> >>> +;  operations are serialized.
>> >>> +;
>> >>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to read.
>> >>> +;
>> >>> +;  @return The value read.
>> >>> +;
>> >>> +MmioRead32Internal
>> >>> +  ldr     r0, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +;
>> >>> +;  Writes a 32-bit MMIO register.
>> >>> +;
>> >>> +;  Writes the 32-bit MMIO register specified by Address with the value specified
>> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +;  and write operations are serialized.
>> >>> +;
>> >>> +;  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to write.
>> >>> +;  @param  Value   The value to write to the MMIO register.
>> >>> +;
>> >>> +MmioWrite32Internal
>> >>> +  dmb     st
>> >>> +  str     r1, [r0]
>> >>> +  bx      lr
>> >>> +
>> >>> +;
>> >>> +;  Reads a 64-bit MMIO register.
>> >>> +;
>> >>> +;  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> >>> +;  returned. This function must guarantee that all MMIO read and write
>> >>> +;  operations are serialized.
>> >>> +;
>> >>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to read.
>> >>> +;
>> >>> +;  @return The value read.
>> >>> +;
>> >>> +MmioRead64Internal
>> >>> +  ldrd    r0, r1, [r0]
>> >>> +  dmb
>> >>> +  bx      lr
>> >>> +
>> >>> +;
>> >>> +;  Writes a 64-bit MMIO register.
>> >>> +;
>> >>> +;  Writes the 64-bit MMIO register specified by Address with the value specified
>> >>> +;  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +;  and write operations are serialized.
>> >>> +;
>> >>> +;  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +;
>> >>> +;  @param  Address The MMIO register to write.
>> >>> +;  @param  Value   The value to write to the MMIO register.
>> >>> +;
>> >>> +MmioWrite64Internal
>> >>> +  dmb     st
>> >>> +  strd    r2, r3, [r0]
>> >>> +  bx      lr
>> >>> +
>> >>> +  END
>> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>> >>> b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>> >>> new file mode 100644
>> >>> index 000000000000..5a1dc87ed2bd
>> >>> --- /dev/null
>> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicArmVirt.inf
>> >>> @@ -0,0 +1,50 @@
>> >>> +## @file
>> >>> +#  Instance of I/O Library using KVM/ARM safe assembler routines
>> >>> +#
>> >>> +#  Copyright (c) 2007 - 2015, Intel Corporation. All rights reserved.<BR>
>> >>> +#  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
>> >>> +#  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>> >>> +#  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
>> >>> +#
>> >>> +#  This program and the accompanying materials are licensed and made available
>> >>> +#  under the terms and conditions of the BSD License which accompanies this
>> >>> +#  distribution. The full text of the license may be found at
>> >>> +#  http://opensource.org/licenses/bsd-license.php.
>> >>> +#
>> >>> +#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> >>> +#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> >>> +#
>> >>> +##
>> >>> +
>> >>> +[Defines]
>> >>> +  INF_VERSION                    = 0x0001001A
>> >>> +  BASE_NAME                      = BaseIoLibIntrinsicArmVirt
>> >>> +  FILE_GUID                      = 217102b4-b465-4a1d-a2de-93dd385ec480
>> >>> +  MODULE_TYPE                    = BASE
>> >>> +  VERSION_STRING                 = 1.0
>> >>> +  LIBRARY_CLASS                  = IoLib
>> >>> +
>> >>> +#
>> >>> +#  VALID_ARCHITECTURES           = ARM AARCH64
>> >>> +#
>> >>> +
>> >>> +[Sources]
>> >>> +  IoLibMmioBuffer.c
>> >>> +  BaseIoLibIntrinsicInternal.h
>> >>> +  IoHighLevel.c
>> >>> +
>> >>> +[Sources.ARM]
>> >>> +  IoLibArmVirt.c
>> >>> +  Arm/ArmVirtMmio.S   | GCC
>> >>> +  Arm/ArmVirtMmio.asm | RVCT
>> >>> +
>> >>> +[Sources.AARCH64]
>> >>> +  IoLibArmVirt.c
>> >>> +  AArch64/ArmVirtMmio.S
>> >>> +
>> >>> +[Packages]
>> >>> +  MdePkg/MdePkg.dec
>> >>> +
>> >>> +[LibraryClasses]
>> >>> +  DebugLib
>> >>> +  BaseLib
>> >>> diff --git a/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
>> >>> new file mode 100644
>> >>> index 000000000000..154d583246ac
>> >>> --- /dev/null
>> >>> +++ b/MdePkg/Library/BaseIoLibIntrinsic/IoLibArmVirt.c
>> >>> @@ -0,0 +1,641 @@
>> >>> +/** @file
>> >>> +  I/O Library for ARM.
>> >>> +
>> >>> +  Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
>> >>> +  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
>> >>> +  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
>> >>> +  Copyright (c) 2018, Linaro, Ltd. All rights reserved.<BR>
>> >>> +
>> >>> +  This program and the accompanying materials are licensed and made available
>> >>> +  under the terms and conditions of the BSD License which accompanies this
>> >>> +  distribution. The full text of the license may be found at
>> >>> +  http://opensource.org/licenses/bsd-license.php.
>> >>> +
>> >>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
>> >>> +  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>> >>> +
>> >>> +**/
>> >>> +
>> >>> +#include "BaseIoLibIntrinsicInternal.h"
>> >>> +
>> >>> +UINT8
>> >>> +EFIAPI
>> >>> +MmioRead8Internal (
>> >>> +  IN      UINTN                     Address
>> >>> +  );
>> >>> +
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +MmioWrite8Internal (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT8                     Value
>> >>> +  );
>> >>> +
>> >>> +UINT16
>> >>> +EFIAPI
>> >>> +MmioRead16Internal (
>> >>> +  IN      UINTN                     Address
>> >>> +  );
>> >>> +
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +MmioWrite16Internal (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT16                    Value
>> >>> +  );
>> >>> +
>> >>> +UINT32
>> >>> +EFIAPI
>> >>> +MmioRead32Internal (
>> >>> +  IN      UINTN                     Address
>> >>> +  );
>> >>> +
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +MmioWrite32Internal (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT32                    Value
>> >>> +  );
>> >>> +
>> >>> +UINT64
>> >>> +EFIAPI
>> >>> +MmioRead64Internal (
>> >>> +  IN      UINTN                     Address
>> >>> +  );
>> >>> +
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +MmioWrite64Internal (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT64                    Value
>> >>> +  );
>> >>> +
>> >>> +/**
>> >>> +  Reads an 8-bit I/O port.
>> >>> +
>> >>> +  Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
>> >>> +  This function must guarantee that all I/O read and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT8
>> >>> +EFIAPI
>> >>> +IoRead8 (
>> >>> +  IN      UINTN                     Port
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return 0;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes an 8-bit I/O port.
>> >>> +
>> >>> +  Writes the 8-bit I/O port specified by Port with the value specified by Value
>> >>> +  and returns Value. This function must guarantee that all I/O read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to write.
>> >>> +  @param  Value The value to write to the I/O port.
>> >>> +
>> >>> +  @return The value written the I/O port.
>> >>> +
>> >>> +**/
>> >>> +UINT8
>> >>> +EFIAPI
>> >>> +IoWrite8 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINT8                     Value
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return Value;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 16-bit I/O port.
>> >>> +
>> >>> +  Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
>> >>> +  This function must guarantee that all I/O read and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT16
>> >>> +EFIAPI
>> >>> +IoRead16 (
>> >>> +  IN      UINTN                     Port
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return 0;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a 16-bit I/O port.
>> >>> +
>> >>> +  Writes the 16-bit I/O port specified by Port with the value specified by Value
>> >>> +  and returns Value. This function must guarantee that all I/O read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to write.
>> >>> +  @param  Value The value to write to the I/O port.
>> >>> +
>> >>> +  @return The value written the I/O port.
>> >>> +
>> >>> +**/
>> >>> +UINT16
>> >>> +EFIAPI
>> >>> +IoWrite16 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINT16                    Value
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return Value;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 32-bit I/O port.
>> >>> +
>> >>> +  Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
>> >>> +  This function must guarantee that all I/O read and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT32
>> >>> +EFIAPI
>> >>> +IoRead32 (
>> >>> +  IN      UINTN                     Port
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return 0;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a 32-bit I/O port.
>> >>> +
>> >>> +  Writes the 32-bit I/O port specified by Port with the value specified by Value
>> >>> +  and returns Value. This function must guarantee that all I/O read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to write.
>> >>> +  @param  Value The value to write to the I/O port.
>> >>> +
>> >>> +  @return The value written the I/O port.
>> >>> +
>> >>> +**/
>> >>> +UINT32
>> >>> +EFIAPI
>> >>> +IoWrite32 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINT32                    Value
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return Value;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 64-bit I/O port.
>> >>> +
>> >>> +  Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
>> >>> +  This function must guarantee that all I/O read and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 64-bit I/O port operations are not supported, then ASSERT().
>> >>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT64
>> >>> +EFIAPI
>> >>> +IoRead64 (
>> >>> +  IN      UINTN                     Port
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return 0;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a 64-bit I/O port.
>> >>> +
>> >>> +  Writes the 64-bit I/O port specified by Port with the value specified by Value
>> >>> +  and returns Value. This function must guarantee that all I/O read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 64-bit I/O port operations are not supported, then ASSERT().
>> >>> +  If Port is not aligned on a 64-bit boundary, then ASSERT().
>> >>> +
>> >>> +  @param  Port  The I/O port to write.
>> >>> +  @param  Value The value to write to the I/O port.
>> >>> +
>> >>> +  @return The value written to the I/O port.
>> >>> +
>> >>> +**/
>> >>> +UINT64
>> >>> +EFIAPI
>> >>> +IoWrite64 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINT64                    Value
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +  return 0;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads an 8-bit I/O port fifo into a block of memory.
>> >>> +
>> >>> +  Reads the 8-bit I/O fifo port specified by Port.
>> >>> +  The port is read Count times, and the read data is
>> >>> +  stored in the provided Buffer.
>> >>> +
>> >>> +  This function must guarantee that all I/O read and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port    The I/O port to read.
>> >>> +  @param  Count   The number of times to read I/O port.
>> >>> +  @param  Buffer  The buffer to store the read data into.
>> >>> +
>> >>> +**/
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +IoReadFifo8 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINTN                     Count,
>> >>> +  OUT     VOID                      *Buffer
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a block of memory into an 8-bit I/O port fifo.
>> >>> +
>> >>> +  Writes the 8-bit I/O fifo port specified by Port.
>> >>> +  The port is written Count times, and the write data is
>> >>> +  retrieved from the provided Buffer.
>> >>> +
>> >>> +  This function must guarantee that all I/O write and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 8-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port    The I/O port to write.
>> >>> +  @param  Count   The number of times to write I/O port.
>> >>> +  @param  Buffer  The buffer to retrieve the write data from.
>> >>> +
>> >>> +**/
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +IoWriteFifo8 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINTN                     Count,
>> >>> +  IN      VOID                      *Buffer
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 16-bit I/O port fifo into a block of memory.
>> >>> +
>> >>> +  Reads the 16-bit I/O fifo port specified by Port.
>> >>> +  The port is read Count times, and the read data is
>> >>> +  stored in the provided Buffer.
>> >>> +
>> >>> +  This function must guarantee that all I/O read and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port    The I/O port to read.
>> >>> +  @param  Count   The number of times to read I/O port.
>> >>> +  @param  Buffer  The buffer to store the read data into.
>> >>> +
>> >>> +**/
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +IoReadFifo16 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINTN                     Count,
>> >>> +  OUT     VOID                      *Buffer
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a block of memory into a 16-bit I/O port fifo.
>> >>> +
>> >>> +  Writes the 16-bit I/O fifo port specified by Port.
>> >>> +  The port is written Count times, and the write data is
>> >>> +  retrieved from the provided Buffer.
>> >>> +
>> >>> +  This function must guarantee that all I/O write and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 16-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port    The I/O port to write.
>> >>> +  @param  Count   The number of times to write I/O port.
>> >>> +  @param  Buffer  The buffer to retrieve the write data from.
>> >>> +
>> >>> +**/
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +IoWriteFifo16 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINTN                     Count,
>> >>> +  IN      VOID                      *Buffer
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 32-bit I/O port fifo into a block of memory.
>> >>> +
>> >>> +  Reads the 32-bit I/O fifo port specified by Port.
>> >>> +  The port is read Count times, and the read data is
>> >>> +  stored in the provided Buffer.
>> >>> +
>> >>> +  This function must guarantee that all I/O read and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port    The I/O port to read.
>> >>> +  @param  Count   The number of times to read I/O port.
>> >>> +  @param  Buffer  The buffer to store the read data into.
>> >>> +
>> >>> +**/
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +IoReadFifo32 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINTN                     Count,
>> >>> +  OUT     VOID                      *Buffer
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a block of memory into a 32-bit I/O port fifo.
>> >>> +
>> >>> +  Writes the 32-bit I/O fifo port specified by Port.
>> >>> +  The port is written Count times, and the write data is
>> >>> +  retrieved from the provided Buffer.
>> >>> +
>> >>> +  This function must guarantee that all I/O write and write operations are
>> >>> +  serialized.
>> >>> +
>> >>> +  If 32-bit I/O port operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Port    The I/O port to write.
>> >>> +  @param  Count   The number of times to write I/O port.
>> >>> +  @param  Buffer  The buffer to retrieve the write data from.
>> >>> +
>> >>> +**/
>> >>> +VOID
>> >>> +EFIAPI
>> >>> +IoWriteFifo32 (
>> >>> +  IN      UINTN                     Port,
>> >>> +  IN      UINTN                     Count,
>> >>> +  IN      VOID                      *Buffer
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT (FALSE);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads an 8-bit MMIO register.
>> >>> +
>> >>> +  Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
>> >>> +  returned. This function must guarantee that all MMIO read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT8
>> >>> +EFIAPI
>> >>> +MmioRead8 (
>> >>> +  IN      UINTN                     Address
>> >>> +  )
>> >>> +{
>> >>> +  return MmioRead8Internal (Address);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes an 8-bit MMIO register.
>> >>> +
>> >>> +  Writes the 8-bit MMIO register specified by Address with the value specified
>> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +  and write operations are serialized.
>> >>> +
>> >>> +  If 8-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to write.
>> >>> +  @param  Value   The value to write to the MMIO register.
>> >>> +
>> >>> +**/
>> >>> +UINT8
>> >>> +EFIAPI
>> >>> +MmioWrite8 (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT8                     Value
>> >>> +  )
>> >>> +{
>> >>> +  MmioWrite8Internal (Address, Value);
>> >>> +  return Value;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 16-bit MMIO register.
>> >>> +
>> >>> +  Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
>> >>> +  returned. This function must guarantee that all MMIO read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT16
>> >>> +EFIAPI
>> >>> +MmioRead16 (
>> >>> +  IN      UINTN                     Address
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT ((Address & 1) == 0);
>> >>> +
>> >>> +  return MmioRead16Internal (Address);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a 16-bit MMIO register.
>> >>> +
>> >>> +  Writes the 16-bit MMIO register specified by Address with the value specified
>> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +  and write operations are serialized.
>> >>> +
>> >>> +  If 16-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to write.
>> >>> +  @param  Value   The value to write to the MMIO register.
>> >>> +
>> >>> +**/
>> >>> +UINT16
>> >>> +EFIAPI
>> >>> +MmioWrite16 (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT16                    Value
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT ((Address & 1) == 0);
>> >>> +
>> >>> +  MmioWrite16Internal (Address, Value);
>> >>> +  return Value;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 32-bit MMIO register.
>> >>> +
>> >>> +  Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
>> >>> +  returned. This function must guarantee that all MMIO read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT32
>> >>> +EFIAPI
>> >>> +MmioRead32 (
>> >>> +  IN      UINTN                     Address
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT ((Address & 3) == 0);
>> >>> +
>> >>> +  return MmioRead32Internal (Address);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a 32-bit MMIO register.
>> >>> +
>> >>> +  Writes the 32-bit MMIO register specified by Address with the value specified
>> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +  and write operations are serialized.
>> >>> +
>> >>> +  If 32-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to write.
>> >>> +  @param  Value   The value to write to the MMIO register.
>> >>> +
>> >>> +**/
>> >>> +UINT32
>> >>> +EFIAPI
>> >>> +MmioWrite32 (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT32                    Value
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT ((Address & 3) == 0);
>> >>> +
>> >>> +  MmioWrite32Internal (Address, Value);
>> >>> +  return Value;
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Reads a 64-bit MMIO register.
>> >>> +
>> >>> +  Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
>> >>> +  returned. This function must guarantee that all MMIO read and write
>> >>> +  operations are serialized.
>> >>> +
>> >>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to read.
>> >>> +
>> >>> +  @return The value read.
>> >>> +
>> >>> +**/
>> >>> +UINT64
>> >>> +EFIAPI
>> >>> +MmioRead64 (
>> >>> +  IN      UINTN                     Address
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT ((Address & 7) == 0);
>> >>> +
>> >>> +  return MmioRead64Internal (Address);
>> >>> +}
>> >>> +
>> >>> +/**
>> >>> +  Writes a 64-bit MMIO register.
>> >>> +
>> >>> +  Writes the 64-bit MMIO register specified by Address with the value specified
>> >>> +  by Value and returns Value. This function must guarantee that all MMIO read
>> >>> +  and write operations are serialized.
>> >>> +
>> >>> +  If 64-bit MMIO register operations are not supported, then ASSERT().
>> >>> +
>> >>> +  @param  Address The MMIO register to write.
>> >>> +  @param  Value   The value to write to the MMIO register.
>> >>> +
>> >>> +**/
>> >>> +UINT64
>> >>> +EFIAPI
>> >>> +MmioWrite64 (
>> >>> +  IN      UINTN                     Address,
>> >>> +  IN      UINT64                    Value
>> >>> +  )
>> >>> +{
>> >>> +  ASSERT ((Address & 7) == 0);
>> >>> +
>> >>> +  MmioWrite64Internal (Address, Value);
>> >>> +  return Value;
>> >>> +}
>> >>> --
>> >>> 2.17.0
>> >>
>
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Re: [edk2] [PATCH] MdePkg/BaseIoLibIntrinsic: make BaseIoLibIntrinsic safe for ArmVirt/KVM
Posted by Leif Lindholm, 2 weeks ago
This addresses all of the items I mentioned in my review of the
previous solution to this problem, so for me:

Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

On Thu, Jun 07, 2018 at 12:46:45PM +0200, Ard Biesheuvel wrote:
> KVM on ARM refuses to decode load/store instructions used to perform
> I/O to emulated devices, and instead relies on the exception syndrome
> information to describe the operand register, access size, etc.
> This is only possible for instructions that have a single input/output
> register (as opposed to ones that increment the offset register, or
> load/store pair instructions, etc). Otherwise, QEMU crashes with the
> following error
> 
>   error: kvm run failed Function not implemented
>   R00=01010101 R01=00000008 R02=00000048 R03=08000820
>   R04=00000120 R05=7faaa0e0 R06=7faaa0dc R07=7faaa0e8
>   R08=7faaa0ec R09=7faaa088 R10=000000ff R11=00000080
>   R12=ff000000 R13=7fccfe08 R14=7faa835f R15=7faa887c
>   PSR=800001f3 N--- T svc32
>   QEMU: Terminated
> 
> and KVM produces a warning such as the following in the kernel log
> 
>   kvm [17646]: load/store instruction decoding not implemented
> 
> The IoLib implementation provided by MdePkg/Library/BaseIoLibIntrinsic
> is based on C code, and when LTO is in effect, the MMIO accesses could
> be merged with, e.g., manipulations of the loop counter, producing
> opcodes that KVM does not support for emulated MMIO.
> 
> So let's add a special ArmVirt flavor of this library that implements
> that actual load/store operations in assembler, ensuring that the
> instructions involved can be emulated by KVM.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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