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

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

Cc: Jordan Justen <jordan.l.jus...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Ard Biesheuvel <ard.biesheu...@arm.com>
Acked-by: Laszlo Ersek <ler...@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
 OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 47 ++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c 
b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
index b77821d2f989..8c2b34c4a83b 100644
--- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
@@ -879,6 +879,49 @@ WbinvdExit (
   return VmgExit (Ghcb, SVM_EXIT_WBINVD, 0, 0);

 }

 

+/**

+  Handle a RDTSCP event.

+

+  Use the VMGEXIT instruction to handle a RDTSCP 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

+RdtscpExit (

+  IN OUT GHCB                     *Ghcb,

+  IN OUT EFI_SYSTEM_CONTEXT_X64   *Regs,

+  IN     SEV_ES_INSTRUCTION_DATA  *InstructionData

+  )

+{

+  UINT64  Status;

+

+  DecodeModRm (Regs, InstructionData);

+

+  Status = VmgExit (Ghcb, SVM_EXIT_RDTSCP, 0, 0);

+  if (Status != 0) {

+    return Status;

+  }

+

+  if (!GhcbIsRegValid (Ghcb, GhcbRax) ||

+      !GhcbIsRegValid (Ghcb, GhcbRcx) ||

+      !GhcbIsRegValid (Ghcb, GhcbRdx)) {

+    return UnsupportedExit (Ghcb, Regs, InstructionData);

+  }

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

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

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

+

+  return 0;

+}

+

 /**

   Handle a VMMCALL event.

 

@@ -1441,6 +1484,10 @@ VmgExitHandleVc (
     NaeExit = VmmCallExit;

     break;

 

+  case SVM_EXIT_RDTSCP:

+    NaeExit = RdtscpExit;

+    break;

+

   case SVM_EXIT_WBINVD:

     NaeExit = WbinvdExit;

     break;

-- 
2.27.0


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