KVM: x86: fix reporting of AMD speculation bug CPUID leaf

The AMD_* bits have to be set from the vendor-independent
feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
about the vendor and they should be set on Intel processors as well.
On top of this, SSBD, STIBP and AMD_SSB_NO bit were not set, and
VIRT_SSBD does not have to be added manually because it is a
cpufeature that comes directly from the host's CPUID bit.

Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 22c2720cd948e321d3f0021670c1dce1e0b5799f..43caeb6059b9341901f5e49fdd96c4d750dfd0b8 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -729,18 +729,23 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
                        g_phys_as = phys_as;
                entry->eax = g_phys_as | (virt_as << 8);
                entry->edx = 0;
+               entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
+               cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
                /*
-                * IBRS, IBPB and VIRT_SSBD aren't necessarily present in
-                * hardware cpuid
+                * AMD has separate bits for each SPEC_CTRL bit.
+                * arch/x86/kernel/cpu/bugs.c is kind enough to
+                * record that in cpufeatures so use them.
                 */
-               if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
+               if (boot_cpu_has(X86_FEATURE_IBPB))
                        entry->ebx |= F(AMD_IBPB);
-               if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
+               if (boot_cpu_has(X86_FEATURE_IBRS))
                        entry->ebx |= F(AMD_IBRS);
-               if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
-                       entry->ebx |= F(VIRT_SSBD);
-               entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
-               cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
+               if (boot_cpu_has(X86_FEATURE_STIBP))
+                       entry->ebx |= F(AMD_STIBP);
+               if (boot_cpu_has(X86_FEATURE_SSBD))
+                       entry->ebx |= F(AMD_SSBD);
+               if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
+                       entry->ebx |= F(AMD_SSB_NO);
                /*
                 * The preference is to use SPEC CTRL MSR instead of the
                 * VIRT_SPEC MSR.