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[edk2-devel] [PATCH v2 09/11] OvmfPkg/SmmAccess: close and lock SMRAM at default SMBASE

Laszlo Ersek posted 11 patches 5 years, 10 months ago
[edk2-devel] [PATCH v2 09/11] OvmfPkg/SmmAccess: close and lock SMRAM at default SMBASE
Posted by Laszlo Ersek 5 years, 10 months ago 
During normal boot, when EFI_DXE_SMM_READY_TO_LOCK_PROTOCOL is installed
by platform BDS, the SMM IPL locks SMRAM (TSEG) through
EFI_SMM_ACCESS2_PROTOCOL.Lock(). See SmmIplReadyToLockEventNotify() in
"MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c".

During S3 resume, S3Resume2Pei locks SMRAM (TSEG) through
PEI_SMM_ACCESS_PPI.Lock(), before executing the boot script. See
S3ResumeExecuteBootScript() in
"UefiCpuPkg/Universal/Acpi/S3Resume2Pei/S3Resume.c".

Those are precisely the places where the SMRAM at the default SMBASE
should be locked too. Add such an action to SmramAccessLock().

Notes:

- The SMRAM at the default SMBASE doesn't support the "closed and
  unlocked" state (and so it can't be closed without locking it, and it
  cannot be opened after closing it).

- The SMRAM at the default SMBASE isn't (and shouldn't) be exposed with
  another EFI_SMRAM_DESCRIPTOR in the GetCapabilities() members of
  EFI_SMM_ACCESS2_PROTOCOL / PEI_SMM_ACCESS_PPI. That's because the SMRAM
  in question is not "general purpose"; it's only QEMU's solution to
  protect the initial SMI handler from the OS, when a VCPU is hot-plugged.

  Consequently, the state of the SMRAM at the default SMBASE is not
  reflected in the "OpenState" / "LockState" fields of the protocol and
  PPI.

- An alternative to extending SmramAccessLock() would be to register an
  EFI_DXE_SMM_READY_TO_LOCK_PROTOCOL notify in SmmAccess2Dxe (for locking
  at normal boot), and an EDKII_S3_SMM_INIT_DONE_GUID PPI notify in
  SmmAccessPei (for locking at S3 resume).

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
---

Notes:
    v2:
    - trim Cc list
    - pick up Jiewen's R-b <https://edk2.groups.io/g/devel/message/48166>

 OvmfPkg/SmmAccess/SmmAccess2Dxe.inf |  1 +
 OvmfPkg/SmmAccess/SmmAccessPei.inf  |  1 +
 OvmfPkg/SmmAccess/SmramInternal.h   |  8 +++++++
 OvmfPkg/SmmAccess/SmmAccess2Dxe.c   |  7 ++++++
 OvmfPkg/SmmAccess/SmmAccessPei.c    |  6 +++++
 OvmfPkg/SmmAccess/SmramInternal.c   | 25 ++++++++++++++++++++
 6 files changed, 48 insertions(+)

diff --git a/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf b/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
index 7ced6b4e7ff4..d86381d0fbe2 100644
--- a/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
+++ b/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
@@ -49,6 +49,7 @@ [FeaturePcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
 
 [Pcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes
 
 [Depex]
diff --git a/OvmfPkg/SmmAccess/SmmAccessPei.inf b/OvmfPkg/SmmAccess/SmmAccessPei.inf
index d73a029cc790..1698c4ce6c92 100644
--- a/OvmfPkg/SmmAccess/SmmAccessPei.inf
+++ b/OvmfPkg/SmmAccess/SmmAccessPei.inf
@@ -54,6 +54,7 @@ [FeaturePcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
 
 [Pcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes
 
 [Ppis]
diff --git a/OvmfPkg/SmmAccess/SmramInternal.h b/OvmfPkg/SmmAccess/SmramInternal.h
index 74d962b4ecae..a4d8827adfe4 100644
--- a/OvmfPkg/SmmAccess/SmramInternal.h
+++ b/OvmfPkg/SmmAccess/SmramInternal.h
@@ -38,6 +38,14 @@ InitQ35TsegMbytes (
   VOID
   );
 
+/**
+  Save PcdQ35SmramAtDefaultSmbase into mQ35SmramAtDefaultSmbase.
+**/
+VOID
+InitQ35SmramAtDefaultSmbase (
+  VOID
+  );
+
 /**
   Read the MCH_SMRAM and ESMRAMC registers, and update the LockState and
   OpenState fields in the PEI_SMM_ACCESS_PPI / EFI_SMM_ACCESS2_PROTOCOL object,
diff --git a/OvmfPkg/SmmAccess/SmmAccess2Dxe.c b/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
index e098f6f15f77..3691a6cd1f10 100644
--- a/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
+++ b/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
@@ -145,6 +145,13 @@ SmmAccess2DxeEntryPoint (
 
   InitQ35TsegMbytes ();
   GetStates (&mAccess2.LockState, &mAccess2.OpenState);
+
+  //
+  // SmramAccessLock() depends on "mQ35SmramAtDefaultSmbase"; init the latter
+  // just before exposing the former via EFI_SMM_ACCESS2_PROTOCOL.Lock().
+  //
+  InitQ35SmramAtDefaultSmbase ();
+
   return gBS->InstallMultipleProtocolInterfaces (&ImageHandle,
                 &gEfiSmmAccess2ProtocolGuid, &mAccess2,
                 NULL);
diff --git a/OvmfPkg/SmmAccess/SmmAccessPei.c b/OvmfPkg/SmmAccess/SmmAccessPei.c
index d67850651c58..c8bbc17e907a 100644
--- a/OvmfPkg/SmmAccess/SmmAccessPei.c
+++ b/OvmfPkg/SmmAccess/SmmAccessPei.c
@@ -372,6 +372,12 @@ SmmAccessPeiEntryPoint (
   CopyMem (GuidHob, &SmramMap[DescIdxSmmS3ResumeState],
     sizeof SmramMap[DescIdxSmmS3ResumeState]);
 
+  //
+  // SmramAccessLock() depends on "mQ35SmramAtDefaultSmbase"; init the latter
+  // just before exposing the former via PEI_SMM_ACCESS_PPI.Lock().
+  //
+  InitQ35SmramAtDefaultSmbase ();
+
   //
   // We're done. The next step should succeed, but even if it fails, we can't
   // roll back the above BuildGuidHob() allocation, because PEI doesn't support
diff --git a/OvmfPkg/SmmAccess/SmramInternal.c b/OvmfPkg/SmmAccess/SmramInternal.c
index 09657d0f9b0f..0b07dc667b3f 100644
--- a/OvmfPkg/SmmAccess/SmramInternal.c
+++ b/OvmfPkg/SmmAccess/SmramInternal.c
@@ -21,6 +21,12 @@
 //
 UINT16 mQ35TsegMbytes;
 
+//
+// The value of PcdQ35SmramAtDefaultSmbase is saved into this variable at
+// module startup.
+//
+STATIC BOOLEAN mQ35SmramAtDefaultSmbase;
+
 /**
   Save PcdQ35TsegMbytes into mQ35TsegMbytes.
 **/
@@ -32,6 +38,17 @@ InitQ35TsegMbytes (
   mQ35TsegMbytes = PcdGet16 (PcdQ35TsegMbytes);
 }
 
+/**
+  Save PcdQ35SmramAtDefaultSmbase into mQ35SmramAtDefaultSmbase.
+**/
+VOID
+InitQ35SmramAtDefaultSmbase (
+  VOID
+  )
+{
+  mQ35SmramAtDefaultSmbase = PcdGetBool (PcdQ35SmramAtDefaultSmbase);
+}
+
 /**
   Read the MCH_SMRAM and ESMRAMC registers, and update the LockState and
   OpenState fields in the PEI_SMM_ACCESS_PPI / EFI_SMM_ACCESS2_PROTOCOL object,
@@ -125,6 +142,14 @@ SmramAccessLock (
   PciOr8 (DRAMC_REGISTER_Q35 (MCH_ESMRAMC), MCH_ESMRAMC_T_EN);
   PciOr8 (DRAMC_REGISTER_Q35 (MCH_SMRAM),   MCH_SMRAM_D_LCK);
 
+  //
+  // Close & lock the SMRAM at the default SMBASE, if it exists.
+  //
+  if (mQ35SmramAtDefaultSmbase) {
+    PciWrite8 (DRAMC_REGISTER_Q35 (MCH_DEFAULT_SMBASE_CTL),
+      MCH_DEFAULT_SMBASE_LCK);
+  }
+
   GetStates (LockState, OpenState);
   if (*OpenState || !*LockState) {
     return EFI_DEVICE_ERROR;
-- 
2.19.1.3.g30247aa5d201



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