From 8715f05269bfbc6453e25e80825d781a82902f8e Mon Sep 17 00:00:00 2001 From: Jim Mattson Date: Fri, 13 Dec 2019 16:15:16 -0800 Subject: 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: 4c6903a0f9d76 ("KVM: x86: fix reporting of AMD speculation bug CPUID leaf") Signed-off-by: Jim Mattson Reviewed-by: Jacob Xu Reviewed-by: Peter Shier Cc: Paolo Bonzini Cc: stable@vger.kernel.org Reported-by: Eric Biggers Signed-off-by: Paolo Bonzini --- arch/x86/kvm/cpuid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index dd18aa6fa317..bf715e5fd35c 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -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); -- cgit v1.2.3-58-ga151