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Date: Wed, 13 Jan 2021 16:36:59 -0800 From: Sean Christopherson <seanjc@...gle.com> To: Paolo Bonzini <pbonzini@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org> Cc: Sean Christopherson <seanjc@...gle.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, Jim Mattson <jmattson@...gle.com>, Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>, Tom Lendacky <thomas.lendacky@....com>, Brijesh Singh <brijesh.singh@....com> Subject: [PATCH v2 05/14] KVM: x86: Override reported SME/SEV feature flags with host mask Add a reverse-CPUID entry for the memory encryption word, 0x8000001F.EAX, and use it to override the supported CPUID flags reported to userspace. Masking the reported CPUID flags avoids over-reporting KVM support, e.g. without the mask a SEV-SNP capable CPU may incorrectly advertise SNP support to userspace. Cc: Brijesh Singh <brijesh.singh@....com> Cc: Tom Lendacky <thomas.lendacky@....com> Signed-off-by: Sean Christopherson <seanjc@...gle.com> --- arch/x86/kvm/cpuid.c | 2 ++ arch/x86/kvm/cpuid.h | 1 + 2 files changed, 3 insertions(+) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 13036cf0b912..b7618cdd06b5 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -855,6 +855,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) case 0x8000001F: if (!boot_cpu_has(X86_FEATURE_SEV)) entry->eax = entry->ebx = entry->ecx = entry->edx = 0; + else + cpuid_entry_override(entry, CPUID_8000_001F_EAX); break; /*Add support for Centaur's CPUID instruction*/ case 0xC0000000: diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index dc921d76e42e..8b6fc9bde248 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -63,6 +63,7 @@ static const struct cpuid_reg reverse_cpuid[] = { [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX}, [CPUID_7_EDX] = { 7, 0, CPUID_EDX}, [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX}, + [CPUID_8000_001F_EAX] = {0x8000001f, 1, CPUID_EAX}, }; /* -- 2.30.0.284.gd98b1dd5eaa7-goog
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