kvm: x86: Host feature SSBD doesn't imply guest feature SPEC_CTRL_SSBD
commit5.4-rM2-2.2.x-imx-squashed396d2e878f
upstream. The host reports support for the synthetic feature X86_FEATURE_SSBD when any of the three following hardware features are set: CPUID.(EAX=7,ECX=0):EDX.SSBD[bit 31] CPUID.80000008H:EBX.AMD_SSBD[bit 24] CPUID.80000008H:EBX.VIRT_SSBD[bit 25] Either of the first two hardware features implies the existence of the IA32_SPEC_CTRL MSR, but CPUID.80000008H:EBX.VIRT_SSBD[bit 25] does not. Therefore, CPUID.(EAX=7,ECX=0):EDX.SSBD[bit 31] should only be set in the guest if CPUID.(EAX=7,ECX=0):EDX.SSBD[bit 31] or CPUID.80000008H:EBX.AMD_SSBD[bit 24] is set on the host. Fixes:0c54914d0c
("KVM: x86: use Intel speculation bugs and features as derived in generic x86 code") Signed-off-by: Jim Mattson <jmattson@google.com> Reviewed-by: Jacob Xu <jacobhxu@google.com> Reviewed-by: Peter Shier <pshier@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: stable@vger.kernel.org Reported-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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0c304e5368
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edaeb11337
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@ -402,7 +402,8 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
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entry->edx |= F(SPEC_CTRL);
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if (boot_cpu_has(X86_FEATURE_STIBP))
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entry->edx |= F(INTEL_STIBP);
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if (boot_cpu_has(X86_FEATURE_SSBD))
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if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
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boot_cpu_has(X86_FEATURE_AMD_SSBD))
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entry->edx |= F(SPEC_CTRL_SSBD);
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/*
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* We emulate ARCH_CAPABILITIES in software even
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