BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
Under SEV-ES, a MWAIT/MWAITX intercept generates a #VC exception.
VMGEXIT must be used to allow the hypervisor to handle this intercept.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 36 ++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
index bb068a45ae00..9d93e30a8ea4 100644
--- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
@@ -854,6 +854,38 @@ MmioExit (
return Status;
}
+/**
+ Handle a MWAIT event.
+
+ Use the VMGEXIT instruction to handle a MWAIT event.
+
+ @param[in, out] Ghcb Pointer to the Guest-Hypervisor Communication
+ Block
+ @param[in, out] Regs x64 processor context
+ @param[in] InstructionData Instruction parsing context
+
+ @return 0 Event handled successfully
+ @return Others New exception value to propagate
+
+**/
+STATIC
+UINT64
+MwaitExit (
+ IN OUT GHCB *Ghcb,
+ IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN SEV_ES_INSTRUCTION_DATA *InstructionData
+ )
+{
+ DecodeModRm (Regs, InstructionData);
+
+ Ghcb->SaveArea.Rax = Regs->Rax;
+ GhcbSetRegValid (Ghcb, GhcbRax);
+ Ghcb->SaveArea.Rcx = Regs->Rcx;
+ GhcbSetRegValid (Ghcb, GhcbRcx);
+
+ return VmgExit (Ghcb, SVM_EXIT_MWAIT, 0, 0);
+}
+
/**
Handle a MONITOR event.
@@ -1530,6 +1562,10 @@ VmgExitHandleVc (
NaeExit = MonitorExit;
break;
+ case SVM_EXIT_MWAIT:
+ NaeExit = MwaitExit;
+ break;
+
case SVM_EXIT_NPF:
NaeExit = MmioExit;
break;
--
2.27.0
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