1 files changed, 66 insertions, 1 deletions
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
index bc891c2636..2d2136f805 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
@@ -14,6 +14,46 @@
 
 #include "SnpPageStateChange.h"
 
+typedef struct {
+  UINT64    StartAddress;
+  UINT64    EndAddress;
+} SNP_PRE_VALIDATED_RANGE;
+
+STATIC SNP_PRE_VALIDATED_RANGE  mPreValidatedRange[] = {
+  // The below address range was part of the SEV OVMF metadata, and range
+  // should be pre-validated by the Hypervisor.
+  {
+    FixedPcdGet32 (PcdOvmfSecPageTablesBase),
+    FixedPcdGet32 (PcdOvmfPeiMemFvBase),
+  },
+};
+
+STATIC
+BOOLEAN
+DetectPreValidatedOverLap (
+  IN    PHYSICAL_ADDRESS         StartAddress,
+  IN    PHYSICAL_ADDRESS         EndAddress,
+  OUT   SNP_PRE_VALIDATED_RANGE  *OverlapRange
+  )
+{
+  UINTN  i;
+
+  //
+  // Check if the specified address range exist in pre-validated array.
+  //
+  for (i = 0; i < ARRAY_SIZE (mPreValidatedRange); i++) {
+    if ((mPreValidatedRange[i].StartAddress < EndAddress) &&
+        (StartAddress < mPreValidatedRange[i].EndAddress))
+    {
+      OverlapRange->StartAddress = mPreValidatedRange[i].StartAddress;
+      OverlapRange->EndAddress   = mPreValidatedRange[i].EndAddress;
+      return TRUE;
+    }
+  }
+
+  return FALSE;
+}
+
 /**
   Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
 
@@ -28,9 +68,34 @@ MemEncryptSevSnpPreValidateSystemRam (
   IN UINTN             NumPages
   )
 {
+  PHYSICAL_ADDRESS         EndAddress;
+  SNP_PRE_VALIDATED_RANGE  OverlapRange;
+
   if (!MemEncryptSevSnpIsEnabled ()) {
     return;
   }
 
-  InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+  EndAddress = BaseAddress + EFI_PAGES_TO_SIZE (NumPages);
+
+  while (BaseAddress < EndAddress) {
+    //
+    // Check if the range overlaps with the pre-validated ranges.
+    //
+    if (DetectPreValidatedOverLap (BaseAddress, EndAddress, &OverlapRange)) {
+      // Validate the non-overlap regions.
+      if (BaseAddress < OverlapRange.StartAddress) {
+        NumPages = EFI_SIZE_TO_PAGES (OverlapRange.StartAddress - BaseAddress);
+
+        InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+      }
+
+      BaseAddress = OverlapRange.EndAddress;
+      continue;
+    }
+
+    // Validate the remaining pages.
+    NumPages = EFI_SIZE_TO_PAGES (EndAddress - BaseAddress);
+    InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
+    BaseAddress = EndAddress;
+  }
 }