Commit 8715f052 authored by Jim Mattson's avatar Jim Mattson Committed by Paolo Bonzini

kvm: x86: Host feature SSBD doesn't imply guest feature AMD_SSBD

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.80000008H:EBX.AMD_SSBD[bit 24] 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: 4c6903a0 ("KVM: x86: fix reporting of AMD speculation bug CPUID leaf")
Signed-off-by: default avatarJim Mattson <jmattson@google.com>
Reviewed-by: default avatarJacob Xu <jacobhxu@google.com>
Reviewed-by: default avatarPeter Shier <pshier@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Reported-by: default avatarEric Biggers <ebiggers@kernel.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 396d2e87
......@@ -760,7 +760,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
entry->ebx |= F(AMD_IBRS);
if (boot_cpu_has(X86_FEATURE_STIBP))
entry->ebx |= F(AMD_STIBP);
if (boot_cpu_has(X86_FEATURE_SSBD))
if (boot_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
boot_cpu_has(X86_FEATURE_AMD_SSBD))
entry->ebx |= F(AMD_SSBD);
if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
entry->ebx |= F(AMD_SSB_NO);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment