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[edk2-devel] [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case

duntan posted 1 patch 3 months, 3 weeks ago
Failed in applying to current master (apply log)
There is a newer version of this series
UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
[edk2-devel] [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case
Posted by duntan 3 months, 3 weeks ago 
When creating smm page table, limit maximum
supported physical address bits returned by
CalculateMaximumSupportAddress() to 48 if
5-Level Paging is disabled.
When 5-Level Paging is disabled and the
PhysicalAddressBits retrived from CPU HOB or
CpuId is bigger than 48, only [0, 2^48 -1]
range in 52-bit physical address is mapped
in page table.

Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
---
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
index ddd9be66b5..e6f174ca10 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
@@ -137,11 +137,13 @@ GetSubEntriesNum (
 /**
   Calculate the maximum support address.
 
+  @param[in] Is5LevelPagingNeeded    If 5-level paging enabling is needed.
+
   @return the maximum support address.
 **/
 UINT8
 CalculateMaximumSupportAddress (
-  VOID
+  BOOLEAN  Is5LevelPagingNeeded
   )
 {
   UINT32  RegEax;
@@ -164,6 +166,15 @@ CalculateMaximumSupportAddress (
     }
   }
 
+  //
+  // Only [0, 2^48 -1] in 52-bit physical addresses is mapped in page table
+  // when 5-Level Paging is disabled.
+  //
+  ASSERT (PhysicalAddressBits <= 52);
+  if (!Is5LevelPagingNeeded && (PhysicalAddressBits > 48)) {
+    PhysicalAddressBits = 48;
+  }
+
   return PhysicalAddressBits;
 }
 
@@ -197,7 +208,7 @@ SmmInitPageTable (
   mCpuSmmRestrictedMemoryAccess = PcdGetBool (PcdCpuSmmRestrictedMemoryAccess);
   m1GPageTableSupport           = Is1GPageSupport ();
   m5LevelPagingNeeded           = Is5LevelPagingNeeded ();
-  mPhysicalAddressBits          = CalculateMaximumSupportAddress ();
+  mPhysicalAddressBits          = CalculateMaximumSupportAddress (m5LevelPagingNeeded);
   PatchInstructionX86 (gPatch5LevelPagingNeeded, m5LevelPagingNeeded, 1);
   if (m5LevelPagingNeeded) {
     mPagingMode = m1GPageTableSupport ? Paging5Level1GB : Paging5Level;
-- 
2.31.1.windows.1



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Re: [edk2-devel] [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case
Posted by Gerd Hoffmann 3 months, 3 weeks ago 
On Wed, Jan 10, 2024 at 04:05:44PM +0800, Dun Tan wrote:
> When creating smm page table, limit maximum
> supported physical address bits returned by
> CalculateMaximumSupportAddress() to 48 if
> 5-Level Paging is disabled.
> When 5-Level Paging is disabled and the
> PhysicalAddressBits retrived from CPU HOB or
> CpuId is bigger than 48, only [0, 2^48 -1]
> range in 52-bit physical address is mapped
> in page table.

I think this is wrong.  Virtual addresses are sign-extended,
i.e. the virtual address space without 5-level paging is:

 0x0000000000000000 -> 0x00007fffffffffff and
 0xffff800000000000 -> 0xffffffffffffffff

Therefore identity-mapping works for [0, 2^47-1] only.

take care,
  Gerd



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Re: [edk2-devel] [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case
Posted by duntan 3 months, 2 weeks ago 
Hi Gerd,

Thanks for your comments. I agree with your opinion. Will change the code and related comments in V2 patch.

Thanks,
Dun

-----Original Message-----
From: Gerd Hoffmann <kraxel@redhat.com> 
Sent: Wednesday, January 10, 2024 6:55 PM
To: Tan, Dun <dun.tan@intel.com>
Cc: devel@edk2.groups.io; Ni, Ray <ray.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>
Subject: Re: [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case

On Wed, Jan 10, 2024 at 04:05:44PM +0800, Dun Tan wrote:
> When creating smm page table, limit maximum supported physical address 
> bits returned by
> CalculateMaximumSupportAddress() to 48 if 5-Level Paging is disabled.
> When 5-Level Paging is disabled and the PhysicalAddressBits retrived 
> from CPU HOB or CpuId is bigger than 48, only [0, 2^48 -1] range in 
> 52-bit physical address is mapped in page table.

I think this is wrong.  Virtual addresses are sign-extended, i.e. the virtual address space without 5-level paging is:

 0x0000000000000000 -> 0x00007fffffffffff and
 0xffff800000000000 -> 0xffffffffffffffff

Therefore identity-mapping works for [0, 2^47-1] only.

take care,
  Gerd



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Re: [edk2-devel] [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case
Posted by Laszlo Ersek 3 months, 2 weeks ago 
On 1/10/24 11:54, Gerd Hoffmann wrote:
> On Wed, Jan 10, 2024 at 04:05:44PM +0800, Dun Tan wrote:
>> When creating smm page table, limit maximum
>> supported physical address bits returned by
>> CalculateMaximumSupportAddress() to 48 if
>> 5-Level Paging is disabled.
>> When 5-Level Paging is disabled and the
>> PhysicalAddressBits retrived from CPU HOB or
>> CpuId is bigger than 48, only [0, 2^48 -1]
>> range in 52-bit physical address is mapped
>> in page table.
> 
> I think this is wrong.  Virtual addresses are sign-extended,
> i.e. the virtual address space without 5-level paging is:
> 
>  0x0000000000000000 -> 0x00007fffffffffff and
>  0xffff800000000000 -> 0xffffffffffffffff
> 
> Therefore identity-mapping works for [0, 2^47-1] only.

I'd have never noticed this. I'll happily defer reviewing this patch to
you then! :)

Thanks!
Laszlo



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Re: [edk2-devel] [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case
Posted by Ni, Ray 3 months, 3 weeks ago 
Reviewed-by: Ray Ni <ray.ni@intel.com>

Thanks,
Ray
> -----Original Message-----
> From: Tan, Dun <dun.tan@intel.com>
> Sent: Wednesday, January 10, 2024 4:06 PM
> To: devel@edk2.groups.io
> Cc: Ni, Ray <ray.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>; Kumar,
> Rahul R <rahul.r.kumar@intel.com>; Gerd Hoffmann <kraxel@redhat.com>
> Subject: [PATCH] UefiCpuPkg:Limit PhysicalAddressBits in speicial case
> 
> When creating smm page table, limit maximum
> supported physical address bits returned by
> CalculateMaximumSupportAddress() to 48 if
> 5-Level Paging is disabled.
> When 5-Level Paging is disabled and the
> PhysicalAddressBits retrived from CPU HOB or
> CpuId is bigger than 48, only [0, 2^48 -1]
> range in 52-bit physical address is mapped
> in page table.
> 
> Signed-off-by: Dun Tan <dun.tan@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
> index ddd9be66b5..e6f174ca10 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
> @@ -137,11 +137,13 @@ GetSubEntriesNum (
>  /**
>    Calculate the maximum support address.
> 
> +  @param[in] Is5LevelPagingNeeded    If 5-level paging enabling is needed.
> +
>    @return the maximum support address.
>  **/
>  UINT8
>  CalculateMaximumSupportAddress (
> -  VOID
> +  BOOLEAN  Is5LevelPagingNeeded
>    )
>  {
>    UINT32  RegEax;
> @@ -164,6 +166,15 @@ CalculateMaximumSupportAddress (
>      }
>    }
> 
> +  //
> +  // Only [0, 2^48 -1] in 52-bit physical addresses is mapped in page table
> +  // when 5-Level Paging is disabled.
> +  //
> +  ASSERT (PhysicalAddressBits <= 52);
> +  if (!Is5LevelPagingNeeded && (PhysicalAddressBits > 48)) {
> +    PhysicalAddressBits = 48;
> +  }
> +
>    return PhysicalAddressBits;
>  }
> 
> @@ -197,7 +208,7 @@ SmmInitPageTable (
>    mCpuSmmRestrictedMemoryAccess = PcdGetBool
> (PcdCpuSmmRestrictedMemoryAccess);
>    m1GPageTableSupport           = Is1GPageSupport ();
>    m5LevelPagingNeeded           = Is5LevelPagingNeeded ();
> -  mPhysicalAddressBits          = CalculateMaximumSupportAddress ();
> +  mPhysicalAddressBits          = CalculateMaximumSupportAddress
> (m5LevelPagingNeeded);
>    PatchInstructionX86 (gPatch5LevelPagingNeeded, m5LevelPagingNeeded,
> 1);
>    if (m5LevelPagingNeeded) {
>      mPagingMode = m1GPageTableSupport ? Paging5Level1GB : Paging5Level;
> --
> 2.31.1.windows.1



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