[edk2-devel] [PATCH v9 24/46] OvmfPkg/VmgExitLib: Add support for MONITOR/MONITORX NAE events

[Lendacky, Thomas]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

Under SEV-ES, a MONITOR/MONITORX intercept generates a #VC exception.
VMGEXIT must be used to allow the hypervisor to handle this intercept.

Cc: Jordan Justen <jordan.l.justen at intel.com>
Cc: Laszlo Ersek <lersek at redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
Acked-by: Laszlo Ersek <lersek at redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
---
 OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 38 ++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
index 8c2b34c4a83b..bb068a45ae00 100644
--- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
@@ -854,6 +854,40 @@ MmioExit (
   return Status;

 }

 

+/**

+  Handle a MONITOR event.

+

+  Use the VMGEXIT instruction to handle a MONITOR 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

+MonitorExit (

+  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;  // Identity mapped, so VA = PA

+  GhcbSetRegValid (Ghcb, GhcbRax);

+  Ghcb->SaveArea.Rcx = Regs->Rcx;

+  GhcbSetRegValid (Ghcb, GhcbRcx);

+  Ghcb->SaveArea.Rdx = Regs->Rdx;

+  GhcbSetRegValid (Ghcb, GhcbRdx);

+

+  return VmgExit (Ghcb, SVM_EXIT_MONITOR, 0, 0);

+}

+

 /**

   Handle a WBINVD event.

 

@@ -1492,6 +1526,10 @@ VmgExitHandleVc (
     NaeExit = WbinvdExit;

     break;

 

+  case SVM_EXIT_MONITOR:

+    NaeExit = MonitorExit;

+    break;

+

   case SVM_EXIT_NPF:

     NaeExit = MmioExit;

     break;

-- 
2.27.0


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