Re: [edk2-devel] [Patch V6 01/14] OvmfPkg:Remove code that apply AddressEncMask to non-leaf entry

["duntan" <dun.tan@intel.com>]

Hi all,

Could you please help to review this patch?

Thanks,
Dun

-----Original Message-----
From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of duntan
Sent: Friday, June 9, 2023 5:16 PM
To: devel@edk2.groups.io
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>; Yao, Jiewen <jiewen.yao@intel.com>; Justen, Jordan L <jordan.l.justen@intel.com>; Gerd Hoffmann <kraxel@redhat.com>; Tom Lendacky <thomas.lendacky@amd.com>; Ni, Ray <ray.ni@intel.com>
Subject: [edk2-devel] [Patch V6 01/14] OvmfPkg:Remove code that apply AddressEncMask to non-leaf entry

Remove code that apply AddressEncMask to non-leaf entry when split smm page table by MemEncryptSevLib. In FvbServicesSmm driver, it calls MemEncryptSevClearMmioPageEncMask to clear AddressEncMask bit in page table for a specific range. In AMD SEV feature, this AddressEncMask bit in page table is used to indicate if the memory is guest private memory or shared memory. But all memory used by page table are treated as encrypted regardless of encryption bit.
So remove the EncMask bit for smm non-leaf page table entry doesn't impact AMD SEV feature.
If page split happens in the AddressEncMask bit clear process, there will be some new non-leaf entries with AddressEncMask applied in smm page table. When ReadyToLock, code in PiSmmCpuDxe module will use CpuPageTableLib to modify smm page table. So remove code to apply AddressEncMask for new non-leaf entries since CpuPageTableLib doesn't consume the EncMask PCD.

Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
---
 OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
index cf2441b551..aba2e8c081 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
@@ -233,7 +233,7 @@ Split2MPageTo4K (
   // Fill in 2M page entry.
   //
   *PageEntry2M = ((UINT64)(UINTN)PageTableEntry1 |
-                  IA32_PG_P | IA32_PG_RW | AddressEncMask);
+                  IA32_PG_P | IA32_PG_RW);
 }
 
 /**
@@ -352,7 +352,7 @@ SetPageTablePoolReadOnly (
         PhysicalAddress += LevelSize[Level - 1];
       }
 
-      PageTable[Index] = (UINT64)(UINTN)NewPageTable | AddressEncMask |
+      PageTable[Index] = (UINT64)(UINTN)NewPageTable |
                          IA32_PG_P | IA32_PG_RW;
       PageTable = NewPageTable;
     }
@@ -440,7 +440,7 @@ Split1GPageTo2M (
   // Fill in 1G page entry.
   //
   *PageEntry1G = ((UINT64)(UINTN)PageDirectoryEntry |
-                  IA32_PG_P | IA32_PG_RW | AddressEncMask);
+                  IA32_PG_P | IA32_PG_RW);
 
   PhysicalAddress2M = PhysicalAddress;
   for (IndexOfPageDirectoryEntries = 0;
--
2.31.1.windows.1