Commit 4c6903a0 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

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: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e4427372

arch/x86/kvm/cpuid.c

+13 −8
Original line number Diff line number Diff line
@@ -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.

CRA Git | Maintained and supported by SUSTech CRA and CCSE