From: Sean Christopherson <seanjc@google.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Brijesh Singh <brijesh.singh@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: [PATCH v3 2/2] KVM: x86: Override reported SME/SEV feature flags with host mask
Date: Fri, 22 Jan 2021 12:40:47 -0800 [thread overview]
Message-ID: <20210122204047.2860075-3-seanjc@google.com> (raw)
In-Reply-To: <20210122204047.2860075-1-seanjc@google.com>
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: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.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},
};
/*
--
2.30.0.280.ga3ce27912f-goog
prev parent reply other threads:[~2021-01-22 20:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-22 20:40 [PATCH v3 0/2] x86/cpufeatures: KVM: Add mem encrypt word Sean Christopherson
2021-01-22 20:40 ` [PATCH v3 1/2] x86/cpufeatures: Assign dedicated feature word for CPUID_0x8000001F[EAX] Sean Christopherson
2021-01-22 20:40 ` Sean Christopherson [this message]
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