Reviewed-by: Ray Ni <ray...@intel.com>
> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of duntan
> Sent: Tuesday, May 16, 2023 5:59 PM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.d...@intel.com>; Ni, Ray <ray...@intel.com>; Kumar, Rahul
> R <rahul.r.ku...@intel.com>; Gerd Hoffmann <kra...@redhat.com>
> Subject: [edk2-devel] [Patch V4 08/15] UefiCpuPkg/PiSmmCpuDxeSmm: Clear
> CR0.WP before modify page table
>
> Clear CR0.WP before modify smm page table. Currently, there is
> an assumption that smm pagetable is always RW before ReadyToLock.
> However, when AMD SEV is enabled, FvbServicesSmm driver calls
> MemEncryptSevClearMmioPageEncMask to clear AddressEncMask bit
> in smm page table for this range:
> [PcdOvmfFdBaseAddress,PcdOvmfFdBaseAddress+PcdOvmfFirmwareFdSize]
> If page slpit happens in this process, new memory for smm page
> table is allocated. Then the newly allocated page table memory
> is marked as RO in smm page table in this FvbServicesSmm driver,
> which may lead to PF if smm code doesn't clear CR0.WP before
> modify smm page table when ReadyToLock.
>
> Signed-off-by: Dun Tan <dun....@intel.com>
> Cc: Eric Dong <eric.d...@intel.com>
> Cc: Ray Ni <ray...@intel.com>
> Cc: Rahul Kumar <rahul1.ku...@intel.com>
> Cc: Gerd Hoffmann <kra...@redhat.com>
> ---
> UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 11
> +++++++++++
> UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 5 +++++
> 2 files changed, 16 insertions(+)
>
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> index 4b512edf68..ef0ba9a355 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
> @@ -1036,6 +1036,8 @@ SetMemMapAttributes (
> IA32_MAP_ENTRY *Map;
> UINTN Count;
> UINT64 MemoryAttribute;
> + BOOLEAN WpEnabled;
> + BOOLEAN CetEnabled;
>
> SmmGetSystemConfigurationTable (&gEdkiiPiSmmMemoryAttributesTableGuid,
> (VOID **)&MemoryAttributesTable);
> if (MemoryAttributesTable == NULL) {
> @@ -1078,6 +1080,8 @@ SetMemMapAttributes (
>
> ASSERT_RETURN_ERROR (Status);
>
> + DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
> +
> MemoryMap = MemoryMapStart;
> for (Index = 0; Index < MemoryMapEntryCount; Index++) {
> DEBUG ((DEBUG_VERBOSE, "SetAttribute: Memory Entry - 0x%lx, 0x%x\n",
> MemoryMap->PhysicalStart, MemoryMap->NumberOfPages));
> @@ -1105,6 +1109,7 @@ SetMemMapAttributes (
> MemoryMap = NEXT_MEMORY_DESCRIPTOR (MemoryMap, DescriptorSize);
> }
>
> + EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
> FreePool (Map);
>
> PatchSmmSaveStateMap ();
> @@ -1411,9 +1416,13 @@ SetUefiMemMapAttributes (
> UINTN MemoryMapEntryCount;
> UINTN Index;
> EFI_MEMORY_DESCRIPTOR *Entry;
> + BOOLEAN WpEnabled;
> + BOOLEAN CetEnabled;
>
> DEBUG ((DEBUG_INFO, "SetUefiMemMapAttributes\n"));
>
> + DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
> +
> if (mUefiMemoryMap != NULL) {
> MemoryMapEntryCount = mUefiMemoryMapSize/mUefiDescriptorSize;
> MemoryMap = mUefiMemoryMap;
> @@ -1492,6 +1501,8 @@ SetUefiMemMapAttributes (
> }
> }
>
> + EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
> +
> //
> // Do not free mUefiMemoryAttributesTable, it will be checked in
> IsSmmCommBufferForbiddenAddress().
> //
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> index 1b0b6673e1..5625ba0cac 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
> @@ -574,6 +574,8 @@ InitPaging (
> BOOLEAN Nx;
> IA32_CR4 Cr4;
> BOOLEAN Enable5LevelPaging;
> + BOOLEAN WpEnabled;
> + BOOLEAN CetEnabled;
>
> Cr4.UintN = AsmReadCr4 ();
> Enable5LevelPaging = (BOOLEAN)(Cr4.Bits.LA57 == 1);
> @@ -620,6 +622,7 @@ InitPaging (
> NumberOfPdptEntries = 4;
> }
>
> + DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
> //
> // Go through page table and change 2MB-page into 4KB-page.
> //
> @@ -800,6 +803,8 @@ InitPaging (
> } // end for PML4
> } // end for PML5
>
> + EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
> +
> //
> // Flush TLB
> //
> --
> 2.31.1.windows.1
>
>
>
>
>
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