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Subject[PATCH 1/3] KVM: x86: fix reporting of AMD speculation bug CPUID leaf
Date
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.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/cpuid.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 22c2720cd948..43caeb6059b9 100644
--- 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.
--
1.8.3.1

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