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KVM: x86/cpuid: Clear XFD for component i if the base feature is missing

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According to Intel extended feature disable (XFD) spec, the sub-function i
(i > 1) of CPUID function 0DH enumerates "details for state component i.
ECX[2] enumerates support for XFD support for this state component."

If KVM does not report F(XFD) feature (e.g. due to CONFIG_X86_64),
then the corresponding XFD support for any state component i
should also be removed. Translate this dependency into KVM terms.

Fixes: 690a757d61 ("kvm: x86: Add CPUID support for Intel AMX")
Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220117074531.76925-1-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Like Xu 2022-01-17 15:45:31 +08:00 committed by Paolo Bonzini
parent 6ff94f27fd
commit e973746882
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kvm/cpuid.c
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@ -936,6 +936,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
--array->nent;
continue;
}
if (!kvm_cpu_cap_has(X86_FEATURE_XFD))
entry->ecx &= ~BIT_ULL(2);
entry->edx = 0;
}
break;