KVM: x86: disable MPX if host did not enable MPX XSAVE features

[cascardo/linux.git] / arch / x86 / kvm / cpuid.c

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 6525e92..fa241d4 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -46,11 +46,18 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted)
        return ret;
 }
 
+bool kvm_mpx_supported(void)
+{
+       return ((host_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR))
+                && kvm_x86_ops->mpx_supported());
+}
+EXPORT_SYMBOL_GPL(kvm_mpx_supported);
+
 u64 kvm_supported_xcr0(void)
 {
        u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0;
 
-       if (!kvm_x86_ops->mpx_supported())
+       if (!kvm_mpx_supported())
                xcr0 &= ~(XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
 
        return xcr0;
@@ -97,7 +104,7 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
        if (best && (best->eax & (F(XSAVES) | F(XSAVEC))))
                best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
 
-       vcpu->arch.eager_fpu = use_eager_fpu() || guest_cpuid_has_mpx(vcpu);
+       vcpu->arch.eager_fpu = use_eager_fpu();
        if (vcpu->arch.eager_fpu)
                kvm_x86_ops->fpu_activate(vcpu);
 
@@ -295,7 +302,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 #endif
        unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;
        unsigned f_invpcid = kvm_x86_ops->invpcid_supported() ? F(INVPCID) : 0;
-       unsigned f_mpx = kvm_x86_ops->mpx_supported() ? F(MPX) : 0;
+       unsigned f_mpx = kvm_mpx_supported() ? F(MPX) : 0;
        unsigned f_xsaves = kvm_x86_ops->xsaves_supported() ? F(XSAVES) : 0;
 
        /* cpuid 1.edx */