Re: [PATCH v2 14/21] KVM:VMX: Add a synthetic MSR to allow userspace VMM to access GUEST_SSP

[Edgecombe, Rick P]

On Fri, 2023-04-21 at 09:46 -0400, Yang Weijiang wrote:
> Introduce a host-only synthetic MSR, MSR_KVM_GUEST_SSP, so that the
> VMM
> can read/write the guest's SSP, e.g. to migrate CET state.  Use a
> synthetic
> MSR, e.g. as opposed to a VCPU_REG_, as GUEST_SSP is subject to the
> same
> consistency checks as the PL*_SSP MSRs, i.e. can share code.

It seems this is exposed to the guest? I'm thinking maybe it should not
be. IA32_PL0_SSP comes with some extra checks, so MSR_KVM_GUEST_SSP
seems a bit powerful. I think the guest doesn't need it either.