Messages in this thread | | | Date | Wed, 9 Aug 2023 14:07:29 +0800 | Subject | Re: [PATCH v5 17/19] KVM:x86: Enable guest CET supervisor xstate bit support | From | "Yang, Weijiang" <> |
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On 8/5/2023 6:02 AM, Paolo Bonzini wrote: > On 8/3/23 06:27, Yang Weijiang wrote: >> if (boot_cpu_has(X86_FEATURE_XSAVES)) { >> + u32 eax, ebx, ecx, edx; >> + >> + cpuid_count(0xd, 1, &eax, &ebx, &ecx, &edx); >> rdmsrl(MSR_IA32_XSS, host_xss); >> kvm_caps.supported_xss = host_xss & KVM_SUPPORTED_XSS; >> + if (ecx & XFEATURE_MASK_CET_KERNEL) >> + kvm_caps.supported_xss |= XFEATURE_MASK_CET_KERNEL; >> } > > This is a bit hackish and makes me lean more towards adding support for XFEATURE_MASK_CET_KERNEL in host MSR_IA32_XSS (and then possibly hide it in the actual calls to XSAVE/XRSTORS for non-guest FPU). Yes, if kernel can support CET_U/S bits in XSS, things would be much easier. But if CET_S bit cannot be enabled for somehow, we may have KVM emulation for it. > Paolo >
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