Messages in this thread | | | Subject | Re: [PATCH v3 7/8] KVM:X86: Add XSS bit 11 and 12 support for CET xsaves/xrstors. | From | Paolo Bonzini <> | Date | Fri, 8 Mar 2019 12:32:04 +0100 |
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On 28/02/19 09:44, Yang Weijiang wrote: >>> if (!vmx_xsaves_supported()) >>> return 1; >>> + >>> /* >>> - * The only supported bit as of Skylake is bit 8, but >>> - * it is not supported on KVM. >>> + * Check bits being set are supported in KVM. >> I'd drop the comment altogether, it's pretty obvious from the code that >> were checking which bits are supported. > you won't see these redundancies in next version ;) >>> */ >>> - if (data != 0) >>> + if (data & ~kvm_supported_xss()) >>> return 1;
You should instead check this against CPUID[0xD, 1].EDX:ECX. If CET is disabled in CPUID, the guest should not be able to set it in MSR_IA32_CSS.
Paolo
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