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

[Yang, Weijiang]

On 5/4/2023 1:08 AM, Edgecombe, Rick P wrote:
> 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.

Make sense. The MSR is just for live migration purpose, no need to 
expose it to guest,

will change it, thanks!