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Thu, 29 Oct 2026 06:18:20 +0000 Message-ID: <64ec4478-8c4a-4d98-9c71-da703234c18e@intel.com> Date: Wed, 28 Oct 2026 23:18:16 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 10/28] KVM: VMX: Add support for saving and restoring FRED MSRs Content-Language: en-US To: Binbin Wu , , CC: Paolo Bonzini , Sean Christopherson , Jonathan Corbet , Shuah Khan , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . 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But the patch emulates the access > of the MSR. > Yes, will change the wording to reflect that only the emulation of the access is being added. >> This >> ensures the guest value is fully virtual and does not alter the hardware >> FRED SSP0 MSR. >> ... >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index 8d3999772ac2..0fd5d4edeebb 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -1032,6 +1032,11 @@ struct kvm_vcpu_arch { >> #if IS_ENABLED(CONFIG_HYPERV) >> hpa_t hv_root_tdp; >> #endif >> + /* >> + * Stores the FRED SSP0 MSR when CET is not supported, prompting KVM > Nit: > CET could be more specific, i.e. SHSTK. I am not sure if there is a situation > that one is supported, but the other is not. > Agreed SHSTK is more precise that CET. I think KVM can clear SHSTK but keep IBT in some situations. > "prompting KVM to intercept its accesses" is confusing to me. I believe it meant to say that fred_ssp0_fallback stores the SSP0 MSR value and the intercepted accesses are emulated using this field. I'll reword it to be less ambiguous. >> + * to intercept its accesses. >> + */ >> + u64 fred_ssp0_fallback; >> }; > > [...]