On 06/05/20 15:27, Tom Lendacky wrote:
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
>
> Add support to the #VC exception handler to handle string IO. This
> requires expanding the IO instruction parsing to recognize string based
> IO instructions as well as preparing an un-encrypted buffer to be used
> to transfer (either to or from the guest) the string contents for the IO
> operation. The SW_EXITINFO2 and SW_SCRATCH fields of the GHCB are set
> appropriately for the operation. Multiple VMGEXIT invocations may be
> needed to complete the string IO operation.
>
> 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 | 90 +++++++++++++++++---
> 1 file changed, 76 insertions(+), 14 deletions(-)
>
> diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> index 7c2bb12df10a..b74b13045cfd 100644
> --- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> +++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
> @@ -397,6 +397,26 @@ IoioExitInfo (
> ExitInfo = 0;
>
> switch (*(InstructionData->OpCodes)) {
> + //
> + // INS opcodes
> + //
> + case 0x6C:
> + case 0x6D:
> + ExitInfo |= IOIO_TYPE_INS;
> + ExitInfo |= IOIO_SEG_ES;
> + ExitInfo |= ((Regs->Rdx & 0xffff) << 16);
> + break;
> +
> + //
> + // OUTS opcodes
> + //
> + case 0x6E:
> + case 0x6F:
> + ExitInfo |= IOIO_TYPE_OUTS;
> + ExitInfo |= IOIO_SEG_DS;
> + ExitInfo |= ((Regs->Rdx & 0xffff) << 16);
> + break;
> +
> //
> // IN immediate opcodes
> //
> @@ -445,6 +465,8 @@ IoioExitInfo (
> //
> // Single-byte opcodes
> //
> + case 0x6C:
> + case 0x6E:
> case 0xE4:
> case 0xE6:
> case 0xEC:
> @@ -506,30 +528,70 @@ IoioExit (
> IN SEV_ES_INSTRUCTION_DATA *InstructionData
> )
> {
> - UINT64 ExitInfo1, Status;
> + UINT64 ExitInfo1, ExitInfo2, Status;
> + BOOLEAN IsString;
>
> ExitInfo1 = IoioExitInfo (Regs, InstructionData);
> if (ExitInfo1 == 0) {
> return UnsupportedExit (Ghcb, Regs, InstructionData);
> }
>
> - if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
> - Ghcb->SaveArea.Rax = 0;
> + IsString = ((ExitInfo1 & IOIO_TYPE_STR) != 0) ? TRUE : FALSE;
> + if (IsString) {
> + UINTN IoBytes, VmgExitBytes;
> + UINTN GhcbCount, OpCount;
> +
> + Status = 0;
> +
> + IoBytes = IOIO_DATA_BYTES(ExitInfo1);
(1) missing space before the opening paren, but we're at v9. So my ACK
stands.
Thanks
Laszlo
> + GhcbCount = sizeof (Ghcb->SharedBuffer) / IoBytes;
> +
> + OpCount = ((ExitInfo1 & IOIO_REP) != 0) ? Regs->Rcx : 1;
> + while (OpCount) {
> + ExitInfo2 = MIN (OpCount, GhcbCount);
> + VmgExitBytes = ExitInfo2 * IoBytes;
> +
> + if ((ExitInfo1 & IOIO_TYPE_IN) == 0) {
> + CopyMem (Ghcb->SharedBuffer, (VOID *) Regs->Rsi, VmgExitBytes);
> + Regs->Rsi += VmgExitBytes;
> + }
> +
> + Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
> + Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, ExitInfo2);
> + if (Status != 0) {
> + return Status;
> + }
> +
> + if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
> + CopyMem ((VOID *) Regs->Rdi, Ghcb->SharedBuffer, VmgExitBytes);
> + Regs->Rdi += VmgExitBytes;
> + }
> +
> + if ((ExitInfo1 & IOIO_REP) != 0) {
> + Regs->Rcx -= ExitInfo2;
> + }
> +
> + OpCount -= ExitInfo2;
> + }
> } else {
> - CopyMem (&Ghcb->SaveArea.Rax, &Regs->Rax, IOIO_DATA_BYTES (ExitInfo1));
> - }
> - GhcbSetRegValid (Ghcb, GhcbRax);
> + if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
> + Ghcb->SaveArea.Rax = 0;
> + } else {
> + CopyMem (&Ghcb->SaveArea.Rax, &Regs->Rax, IOIO_DATA_BYTES (ExitInfo1));
> + }
> + GhcbSetRegValid (Ghcb, GhcbRax);
>
> - Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, 0);
> - if (Status != 0) {
> - return Status;
> - }
> + Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, 0);
> + if (Status != 0) {
> + return Status;
> + }
>
> - if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
> - if (!GhcbIsRegValid (Ghcb, GhcbRax)) {
> - return UnsupportedExit (Ghcb, Regs, InstructionData);
> + if ((ExitInfo1 & IOIO_TYPE_IN) != 0) {
> + if (!GhcbIsRegValid (Ghcb, GhcbRax)) {
> + return UnsupportedExit (Ghcb, Regs, InstructionData);
> + }
> + CopyMem (&Regs->Rax, &Ghcb->SaveArea.Rax, IOIO_DATA_BYTES (ExitInfo1));
> }
> - CopyMem (&Regs->Rax, &Ghcb->SaveArea.Rax, IOIO_DATA_BYTES (ExitInfo1));
> }
>
> return 0;
>
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