[edk2-devel] [PATCH 3/3] UefiCpuPkg/PiSmmCpuDxeSmm:Map SMRAM in 4K page granularity

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

This patch is to map SMRAM in 4K page granularity
during SMM page table initialization(SmmInitPageTable)
so as to avoid the SMRAM paging-structure layout
change when SMI happens (PerformRemainingTasks).
The reason is to avoid the Paging-Structure change
impact to the multiple Processors. Refer SDM section
"4.10.4" & "4.10.5".

Currently, SMM BSP needs to update the SMRAM range
paging attribute in smm page table according to the
SmmMemoryAttributesTable when SMM ready to lock
happens. If the SMRAM range is not 4k mapped in page
table, the page table update process may split 1G/2M
paging entries to 4k ones.Meanwhile, all APs are still
running in SMI, which might access the affected
linear-address range between the time of modification
and the time of invalidation access. That will be
a potential problem leading exception happens.

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/SmmCpuMemoryManagement.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 92 insertions(+), 24 deletions(-)

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
index 12f3c0b8e8..0012d63674 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
@@ -1647,49 +1647,115 @@ EdkiiSmmClearMemoryAttributes (
 }
 
 /**
-  Create page table based on input PagingMode and PhysicalAddressBits in smm.
-
-  @param[in]      PagingMode           The paging mode.
-  @param[in]      PhysicalAddressBits  The bits of physical address to map.
+  Create page table based on input PagingMode, LinearAddress and Length.
 
-  @retval         PageTable Address
+  @param[in, out]  PageTable           The pointer to the page table.
+  @param[in]       PagingMode          The paging mode.
+  @param[in]       LinearAddress       The start of the linear address range.
+  @param[in]       Length              The length of the linear address range.
 
 **/
-UINTN
-GenSmmPageTable (
-  IN PAGING_MODE  PagingMode,
-  IN UINT8        PhysicalAddressBits
+VOID
+GenPageTable (
+  IN OUT UINTN        *PageTable,
+  IN     PAGING_MODE  PagingMode,
+  IN     UINT64       LinearAddress,
+  IN     UINT64       Length
   )
 {
+  RETURN_STATUS       Status;
   UINTN               PageTableBufferSize;
-  UINTN               PageTable;
   VOID                *PageTableBuffer;
   IA32_MAP_ATTRIBUTE  MapAttribute;
   IA32_MAP_ATTRIBUTE  MapMask;
-  RETURN_STATUS       Status;
-  UINTN               GuardPage;
-  UINTN               Index;
-  UINT64              Length;
 
-  Length                           = LShiftU64 (1, PhysicalAddressBits);
-  PageTable                        = 0;
-  PageTableBufferSize              = 0;
   MapMask.Uint64                   = MAX_UINT64;
-  MapAttribute.Uint64              = mAddressEncMask;
+  MapAttribute.Uint64              = mAddressEncMask|LinearAddress;
   MapAttribute.Bits.Present        = 1;
   MapAttribute.Bits.ReadWrite      = 1;
   MapAttribute.Bits.UserSupervisor = 1;
   MapAttribute.Bits.Accessed       = 1;
   MapAttribute.Bits.Dirty          = 1;
+  PageTableBufferSize              = 0;
+
+  Status = PageTableMap (
+             PageTable,
+             PagingMode,
+             NULL,
+             &PageTableBufferSize,
+             LinearAddress,
+             Length,
+             &MapAttribute,
+             &MapMask,
+             NULL
+             );
+  if (Status == RETURN_BUFFER_TOO_SMALL) {
+    DEBUG ((DEBUG_INFO, "GenSMMPageTable: 0x%x bytes needed for initial SMM page table\n", PageTableBufferSize));
+    PageTableBuffer = AllocatePageTableMemory (EFI_SIZE_TO_PAGES (PageTableBufferSize));
+    ASSERT (PageTableBuffer != NULL);
+    Status = PageTableMap (
+               PageTable,
+               PagingMode,
+               PageTableBuffer,
+               &PageTableBufferSize,
+               LinearAddress,
+               Length,
+               &MapAttribute,
+               &MapMask,
+               NULL
+               );
+  }
 
-  Status = PageTableMap (&PageTable, PagingMode, NULL, &PageTableBufferSize, 0, Length, &MapAttribute, &MapMask, NULL);
-  ASSERT (Status == RETURN_BUFFER_TOO_SMALL);
-  DEBUG ((DEBUG_INFO, "GenSMMPageTable: 0x%x bytes needed for initial SMM page table\n", PageTableBufferSize));
-  PageTableBuffer = AllocatePageTableMemory (EFI_SIZE_TO_PAGES (PageTableBufferSize));
-  ASSERT (PageTableBuffer != NULL);
-  Status = PageTableMap (&PageTable, PagingMode, PageTableBuffer, &PageTableBufferSize, 0, Length, &MapAttribute, &MapMask, NULL);
   ASSERT (Status == RETURN_SUCCESS);
   ASSERT (PageTableBufferSize == 0);
+}
+
+/**
+  Create page table based on input PagingMode and PhysicalAddressBits in smm.
+
+  @param[in]      PagingMode           The paging mode.
+  @param[in]      PhysicalAddressBits  The bits of physical address to map.
+
+  @retval         PageTable Address
+
+**/
+UINTN
+GenSmmPageTable (
+  IN PAGING_MODE  PagingMode,
+  IN UINT8        PhysicalAddressBits
+  )
+{
+  UINTN          PageTable;
+  RETURN_STATUS  Status;
+  UINTN          GuardPage;
+  UINTN          Index;
+  UINT64         Length;
+  PAGING_MODE    SmramPagingMode;
+
+  PageTable = 0;
+  Length    = LShiftU64 (1, PhysicalAddressBits);
+  ASSERT (Length > mCpuHotPlugData.SmrrBase + mCpuHotPlugData.SmrrSize);
+
+  if (sizeof (UINTN) == sizeof (UINT64)) {
+    SmramPagingMode = m5LevelPagingNeeded ? Paging5Level4KB : Paging4Level4KB;
+  } else {
+    SmramPagingMode = PagingPae4KB;
+  }
+
+  GenPageTable (&PageTable, PagingMode, 0, mCpuHotPlugData.SmrrBase);
+
+  //
+  // Map smram range in 4K page granularity to avoid subsequent page split when smm ready to lock.
+  // If BSP are splitting the 1G/2M paging entries to 512 2M/4K paging entries, and all APs are
+  // still running in SMI at the same time, which might access the affected linear-address range
+  // between the time of modification and the time of invalidation access. That will be a potential
+  // problem leading exception happen.
+  //
+  ASSERT (mCpuHotPlugData.SmrrBase % SIZE_4KB == 0);
+  ASSERT (mCpuHotPlugData.SmrrSize % SIZE_4KB == 0);
+  GenPageTable (&PageTable, SmramPagingMode, mCpuHotPlugData.SmrrBase, mCpuHotPlugData.SmrrSize);
+
+  GenPageTable (&PageTable, PagingMode, mCpuHotPlugData.SmrrBase + mCpuHotPlugData.SmrrSize, Length - mCpuHotPlugData.SmrrBase - mCpuHotPlugData.SmrrSize);
 
   if (FeaturePcdGet (PcdCpuSmmStackGuard)) {
     //
@@ -1698,6 +1764,7 @@ GenSmmPageTable (
     for (Index = 0; Index < gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus; Index++) {
       GuardPage = mSmmStackArrayBase + EFI_PAGE_SIZE + Index * (mSmmStackSize + mSmmShadowStackSize);
       Status    = ConvertMemoryPageAttributes (PageTable, PagingMode, GuardPage, SIZE_4KB, EFI_MEMORY_RP, TRUE, NULL);
+      ASSERT (Status == RETURN_SUCCESS);
     }
   }
 
@@ -1706,6 +1773,7 @@ GenSmmPageTable (
     // Mark [0, 4k] as non-present
     //
     Status = ConvertMemoryPageAttributes (PageTable, PagingMode, 0, SIZE_4KB, EFI_MEMORY_RP, TRUE, NULL);
+    ASSERT (Status == RETURN_SUCCESS);
   }
 
   return (UINTN)PageTable;
-- 
2.31.1.windows.1



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