diff options
Diffstat (limited to 'OvmfPkg/Library/BaseMemEncryptSevLib/X64')
3 files changed, 51 insertions, 1 deletions
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c index bc891c2636..7797febb8a 100644 --- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecSnpSystemRamValidate.c @@ -14,6 +14,43 @@ #include "SnpPageStateChange.h"
+//
+// The variable used for the VMPL check.
+//
+STATIC UINT8 gVmpl0Data[4096];
+
+/**
+ The function checks whether SEV-SNP guest is booted under VMPL0.
+
+ @retval TRUE The guest is booted under VMPL0
+ @retval FALSE The guest is not booted under VMPL0
+ **/
+STATIC
+BOOLEAN
+SevSnpIsVmpl0 (
+ VOID
+ )
+{
+ UINT64 Rdx;
+ EFI_STATUS Status;
+
+ //
+ // There is no straightforward way to query the current VMPL level.
+ // The simplest method is to use the RMPADJUST instruction to change
+ // a page permission to a VMPL level-1, and if the guest kernel is
+ // launched at a level <= 1, then RMPADJUST instruction will return
+ // an error.
+ //
+ Rdx = 1;
+
+ Status = AsmRmpAdjust ((UINT64)gVmpl0Data, 0, Rdx);
+ if (EFI_ERROR (Status)) {
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
/**
Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
@@ -32,5 +69,14 @@ MemEncryptSevSnpPreValidateSystemRam ( return;
}
+ //
+ // The page state change uses the PVALIDATE instruction. The instruction
+ // can be run on VMPL-0 only. If its not VMPL-0 guest then terminate
+ // the boot.
+ //
+ if (!SevSnpIsVmpl0 ()) {
+ SnpPageStateFailureTerminate ();
+ }
+
InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h index b396f0ffbd..43319cc9ed 100644 --- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChange.h @@ -27,4 +27,9 @@ InternalSetPageState ( IN BOOLEAN UseLargeEntry
);
+VOID
+SnpPageStateFailureTerminate (
+ VOID
+ );
+
#endif
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c index 9c552ef5c7..d11aafae84 100644 --- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c +++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c @@ -42,7 +42,6 @@ MemoryStateToGhcbOp ( return Cmd;
}
-STATIC
VOID
SnpPageStateFailureTerminate (
VOID
|