On 05/19/20 23:50, Lendacky, Thomas wrote:
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
>
> Under SEV-ES, a RDTSC 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>
> Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
> ---
> .../Library/VmgExitLib/X64/VmgExitVcHandler.c | 43 +++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c
> b/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c
> index 0cf26c052b32..3d2a9c6f9bc9 100644
> --- a/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c
> +++ b/OvmfPkg/Library/VmgExitLib/X64/VmgExitVcHandler.c
> @@ -1214,6 +1214,45 @@ CpuidExit (
> return 0;
> }
>
> +/**
> + Handle a RDTSC event.
> +
> + Use the VMGEXIT instruction to handle a RDTSC 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
> +
> + @retval 0 Event handled successfully
> + @retval Others New exception value to propagate
> +
> +**/
> +STATIC
> +UINT64
> +RdtscExit (
> + IN OUT GHCB *Ghcb,
> + IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,
> + IN SEV_ES_INSTRUCTION_DATA *InstructionData
> + )
> +{
> + UINT64 Status;
> +
> + Status = VmgExit (Ghcb, SVM_EXIT_RDTSC, 0, 0);
> + if (Status) {
(1) Please write (Status > 0) or (Status != 0) explicitly.
With that:
Acked-by: Laszlo Ersek <ler...@redhat.com>
Thanks,
Laszlo
> + return Status;
> + }
> +
> + if (!GhcbIsRegValid (Ghcb, GhcbRax) ||
> + !GhcbIsRegValid (Ghcb, GhcbRdx)) {
> + return UnsupportedExit (Ghcb, Regs, InstructionData);
> + }
> + Regs->Rax = Ghcb->SaveArea.Rax;
> + Regs->Rdx = Ghcb->SaveArea.Rdx;
> +
> + return 0;
> +}
> +
> /**
> Handle a #VC exception.
>
> @@ -1258,6 +1297,10 @@ VmgExitHandleVc (
>
> ExitCode = Regs->ExceptionData;
> switch (ExitCode) {
> + case SVM_EXIT_RDTSC:
> + NaeExit = RdtscExit;
> + break;
> +
> case SVM_EXIT_CPUID:
> NaeExit = CpuidExit;
> break;
>
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