Re: [PATCH 02/15] KVM: x86: Emulate RDPID only if RDTSCP is supported

[Jim Mattson]

On Tue, May 4, 2021 at 10:17 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>
> Do not advertise emulation support for RDPID if RDTSCP is unsupported.
> RDPID emulation subtly relies on MSR_TSC_AUX to exist in hardware, as
> both vmx_get_msr() and svm_get_msr() will return an error if the MSR is
> unsupported, i.e. ctxt->ops->get_msr() will fail and the emulator will
> inject a #UD.
>
> Note, RDPID emulation also relies on RDTSCP being enabled in the guest,
> but this is a KVM bug and will eventually be fixed.
>
> Fixes: fb6d4d340e05 ("KVM: x86: emulate RDPID")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed by: Jim Mattson <jmattson@xxxxxxxxxx>