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Subject[PATCH 1/8] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors
Date
As an interim measure until SPEC_CTRL is supported by upstream
Linux in cpufeatures, add a function that lets vmx.c and svm.c
know whether to save/restore MSR_IA32_SPEC_CTRL.

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/cpuid.c | 3 ---
arch/x86/kvm/cpuid.h | 22 ++++++++++++++++++++++
2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8e9a07c557f1..767af697c20c 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -67,9 +67,6 @@ u64 kvm_supported_xcr0(void)

#define F(x) bit(X86_FEATURE_##x)

-/* These are scattered features in cpufeatures.h. */
-#define KVM_CPUID_BIT_AVX512_4VNNIW 2
-#define KVM_CPUID_BIT_AVX512_4FMAPS 3
#define KF(x) bit(KVM_CPUID_BIT_##x)

int kvm_update_cpuid(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index c2cea6651279..8d04ccf177ce 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -155,6 +155,28 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu)
return x86_stepping(best->eax);
}

+/* These are scattered features in cpufeatures.h. */
+#define KVM_CPUID_BIT_AVX512_4VNNIW 2
+#define KVM_CPUID_BIT_AVX512_4FMAPS 3
+#define KVM_CPUID_BIT_SPEC_CTRL 26
+#define KVM_CPUID_BIT_STIBP 27
+
+/* CPUID[eax=0x80000008].ebx */
+#define KVM_CPUID_BIT_IBPB_SUPPORT 12
+
+static inline bool cpu_has_spec_ctrl(void)
+{
+ u32 eax, ebx, ecx, edx;
+ cpuid_count(7, 0, &eax, &ebx, &ecx, &edx);
+
+ return edx & bit(KVM_CPUID_BIT_SPEC_CTRL);
+}
+
+static inline bool cpu_has_ibpb_support(void)
+{
+ return cpuid_ebx(0x80000008) & bit(KVM_CPUID_BIT_IBPB_SUPPORT);
+}
+
static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu)
{
return vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT;
--
1.8.3.1

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