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-rw-r--r--OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf2
-rw-r--r--OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c67
2 files changed, 68 insertions, 1 deletions
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
index 0402e49a10..49d5bd1bef 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
@@ -58,3 +58,5 @@
[FixedPcd]
gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase
+ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
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;
+ }
}