On 04/21/21 00:54, Lendacky, Thomas wrote:
> From: Tom Lendacky <thomas.lenda...@amd.com>
>
> 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 <ler...@redhat.com>
> Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
> Cc: Jordan Justen <jordan.l.jus...@intel.com>
> Cc: Brijesh Singh <brijesh.si...@amd.com>
> Cc: James Bottomley <j...@linux.ibm.com>
> Cc: Jiewen Yao <jiewen....@intel.com>
> Cc: Min Xu <min.m...@intel.com>
> Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
> ---
> OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 99 +++++++++++++++++++
> 1 file changed, 99 insertions(+)
>
> diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> index 273f36499988..f9660b757d8e 100644
> --- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> +++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> @@ -678,6 +678,7 @@ MmioExit (
> UINTN Bytes;
> UINT64 *Register;
> UINT8 OpCode, SignByte;
> + UINTN Address;
>
> Bytes = 0;
>
> @@ -727,6 +728,51 @@ 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 += (UINTN) (1 << InstructionData->AddrSize);
> +
> + if (InstructionData->AddrSize == Size8Bits) {
> + Address = *(UINT8 *) InstructionData->Immediate;
> + } else if (InstructionData->AddrSize == Size16Bits) {
> + Address = *(UINT16 *) InstructionData->Immediate;
> + } else if (InstructionData->AddrSize == Size32Bits) {
> + Address = *(UINT32 *) InstructionData->Immediate;
> + } else {
> + Address = *(UINTN *) InstructionData->Immediate;
> + }
(1) Can we simplify this as follows?
InstructionData->ImmediateSize = 1 << InstructionData->AddrSize;
InstructionData->End += InstructionData->ImmediateSize;
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)
> //
> @@ -809,6 +855,58 @@ 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 += (UINTN) (1 << InstructionData->AddrSize);
> +
> + if (InstructionData->AddrSize == Size8Bits) {
> + Address = *(UINT8 *) InstructionData->Immediate;
> + } else if (InstructionData->AddrSize == Size16Bits) {
> + Address = *(UINT16 *) InstructionData->Immediate;
> + } else if (InstructionData->AddrSize == Size32Bits) {
> + Address = *(UINT32 *) InstructionData->Immediate;
> + } else {
> + Address = *(UINTN *) InstructionData->Immediate;
> + }
(2) Similar question as (1).
> +
> + 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;
> + }
(3) This is also seen with opcode 0x8B, but can you remind me please why
we ignore (Bytes == 1) and (Bytes == 2) for zero extension?
> + CopyMem (&Regs->Rax, Ghcb->SharedBuffer, Bytes);
> + break;
> +
> //
> // MMIO read w/ zero-extension ((MOVZX regX, reg/memX)
> //
> @@ -886,6 +984,7 @@ MmioExit (
> break;
>
> default:
> + DEBUG ((DEBUG_INFO, "Invalid MMIO opcode (%x)\n", OpCode));
> Status = GP_EXCEPTION;
> ASSERT (FALSE);
> }
>
(4) We should use the DEBUG_ERROR log mask here.
Thanks
Laszlo
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