Re: [PATCH v15 14/41] KVM: VMX: Emulate read and write to CET MSRs

[Xiaoyao Li]

On 9/16/2025 3:48 PM, Chao Gao wrote:
> On Tue, Sep 16, 2025 at 03:07:06PM +0800, Xiaoyao Li wrote:
> > On 9/13/2025 7:22 AM, Sean Christopherson wrote:
> > > From: Yang Weijiang <weijiang.yang@xxxxxxxxx>
> > >
> > > Add emulation interface for CET MSR access. The emulation code is split
> > > into common part and vendor specific part. The former does common checks
> > > for MSRs, e.g., accessibility, data validity etc., then passes operation
> > > to either XSAVE-managed MSRs via the helpers or CET VMCS fields.
> > >
> > > SSP can only be read via RDSSP. Writing even requires destructive and
> > > potentially faulting operations such as SAVEPREVSSP/RSTORSSP or
> > > SETSSBSY/CLRSSBSY. Let the host use a pseudo-MSR that is just a wrapper
> > > for the GUEST_SSP field of the VMCS.
> > >
> > > Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> > > Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
> > > Tested-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
> > > Tested-by: John Allen <john.allen@xxxxxxx>
> > > Tested-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
> > > Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> > > [sean: drop call to kvm_set_xstate_msr() for S_CET, consolidate code]
> >
> > Is the change/update of "drop call to kvm_set_xstate_msr() for S_CET" true
> > for this patch?
>
> v14 has that call, but it is incorrect. So Sean dropped it. See v14:
>
> https://lore.kernel.org/kvm/20250909093953.202028-12-chao.gao@xxxxxxxxx/

Sorry, my fault. I missed it somehow, when bouncing between the 3 MSR 
handlers.

> > > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> >
> > Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>