[PATCH v3 2/5] OvmfPkg/VmgExitLib: Add support for new MMIO MOV opcodes


Lendacky, Thomas
 

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3345

Enabling TPM support results in guest termination of an SEV-ES guest
because it uses MMIO opcodes that are not currently supported.

Add support for the new MMIO opcodes (0xA0 - 0xA3), MOV instructions which
use a memory offset directly encoded in the instruction. Also, add a DEBUG
statement to identify an unsupported MMIO opcode being used.

Fixes: c45f678a1ea2080344e125dc55b14e4b9f98483d
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 111 ++++++++++++++++++++
1 file changed, 111 insertions(+)

diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
index b716541ad170..41b0c8cc5312 100644
--- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
@@ -680,6 +680,7 @@ MmioExit (
UINTN Bytes;
UINT64 *Register;
UINT8 OpCode, SignByte;
+ UINTN Address;

Bytes = 0;

@@ -729,6 +730,57 @@ MmioExit (
}
break;

+ //
+ // MMIO write (MOV moffsetX, aX)
+ //
+ case 0xA2:
+ Bytes = 1;
+ //
+ // fall through
+ //
+ case 0xA3:
+ Bytes = ((Bytes != 0) ? Bytes :
+ (InstructionData->DataSize == Size16Bits) ? 2 :
+ (InstructionData->DataSize == Size32Bits) ? 4 :
+ (InstructionData->DataSize == Size64Bits) ? 8 :
+ 0);
+
+ InstructionData->ImmediateSize = (UINTN) (1 << InstructionData->AddrSize);
+ InstructionData->End += InstructionData->ImmediateSize;
+
+ //
+ // This code is X64 only, so a possible 8-byte copy to a UINTN is ok.
+ // Use a STATIC_ASSERT to be certain the code is being built as X64.
+ //
+ STATIC_ASSERT (
+ sizeof (UINTN) == sizeof (UINT64),
+ "sizeof (UINTN) != sizeof (UINT64), this file must be built as X64"
+ );
+
+ Address = 0;
+ CopyMem (
+ &Address,
+ InstructionData->Immediate,
+ InstructionData->ImmediateSize
+ );
+
+ Status = ValidateMmioMemory (Ghcb, Address, Bytes);
+ if (Status != 0) {
+ return Status;
+ }
+
+ ExitInfo1 = Address;
+ ExitInfo2 = Bytes;
+ CopyMem (Ghcb->SharedBuffer, &Regs->Rax, Bytes);
+
+ Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
+ VmgSetOffsetValid (Ghcb, GhcbSwScratch);
+ Status = VmgExit (Ghcb, SVM_EXIT_MMIO_WRITE, ExitInfo1, ExitInfo2);
+ if (Status != 0) {
+ return Status;
+ }
+ break;
+
//
// MMIO write (MOV reg/memX, immX)
//
@@ -811,6 +863,64 @@ MmioExit (
CopyMem (Register, Ghcb->SharedBuffer, Bytes);
break;

+ //
+ // MMIO read (MOV aX, moffsetX)
+ //
+ case 0xA0:
+ Bytes = 1;
+ //
+ // fall through
+ //
+ case 0xA1:
+ Bytes = ((Bytes != 0) ? Bytes :
+ (InstructionData->DataSize == Size16Bits) ? 2 :
+ (InstructionData->DataSize == Size32Bits) ? 4 :
+ (InstructionData->DataSize == Size64Bits) ? 8 :
+ 0);
+
+ InstructionData->ImmediateSize = (UINTN) (1 << InstructionData->AddrSize);
+ InstructionData->End += InstructionData->ImmediateSize;
+
+ //
+ // This code is X64 only, so a possible 8-byte copy to a UINTN is ok.
+ // Use a STATIC_ASSERT to be certain the code is being built as X64.
+ //
+ STATIC_ASSERT (
+ sizeof (UINTN) == sizeof (UINT64),
+ "sizeof (UINTN) != sizeof (UINT64), this file must be built as X64"
+ );
+
+ Address = 0;
+ CopyMem (
+ &Address,
+ InstructionData->Immediate,
+ InstructionData->ImmediateSize
+ );
+
+ Status = ValidateMmioMemory (Ghcb, Address, Bytes);
+ if (Status != 0) {
+ return Status;
+ }
+
+ ExitInfo1 = Address;
+ ExitInfo2 = Bytes;
+
+ Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
+ VmgSetOffsetValid (Ghcb, GhcbSwScratch);
+ Status = VmgExit (Ghcb, SVM_EXIT_MMIO_READ, ExitInfo1, ExitInfo2);
+ if (Status != 0) {
+ return Status;
+ }
+
+ if (Bytes == 4) {
+ //
+ // Zero-extend for 32-bit operation
+ //
+ Regs->Rax = 0;
+ }
+ CopyMem (&Regs->Rax, Ghcb->SharedBuffer, Bytes);
+ break;
+
//
// MMIO read w/ zero-extension ((MOVZX regX, reg/memX)
//
@@ -888,6 +998,7 @@ MmioExit (
break;

default:
+ DEBUG ((DEBUG_ERROR, "Invalid MMIO opcode (%x)\n", OpCode));
Status = GP_EXCEPTION;
ASSERT (FALSE);
}
--
2.31.0

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