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

Chao Gao
2025-09-16T07:48:46Z

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@intel.com>
>>
>> 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@google.com>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> Tested-by: Mathias Krause <minipli@grsecurity.net>
>> Tested-by: John Allen <john.allen@amd.com>
>> Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
>> Signed-off-by: Chao Gao <chao.gao@intel.com>
>> [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@intel.com/

>
>> Signed-off-by: Sean Christopherson <seanjc@google.com>
>
>Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>