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Commit a40f0ccd authored by Jim Mattson's avatar Jim Mattson Committed by Greg Kroah-Hartman
Browse files

kvm: x86: Guest BNDCFGS requires guest MPX support 



commit 4439af9f911ae0243ffe4e2dfc12bace49605d8b upstream.

The BNDCFGS MSR should only be exposed to the guest if the guest
supports MPX. (cf. the TSC_AUX MSR and RDTSCP.)

Fixes: 0dd376e7 ("KVM: x86: add MSR_IA32_BNDCFGS to msrs_to_save")
Change-Id: I3ad7c01bda616715137ceac878f3fa7e66b6b387
Signed-off-by: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent be6f33a6

arch/x86/kvm/cpuid.h

+8 −0
Original line number Diff line number Diff line
@@ -143,6 +143,14 @@ static inline bool guest_cpuid_has_pcommit(struct kvm_vcpu *vcpu) 
	return best && (best->ebx & bit(X86_FEATURE_PCOMMIT));

}



static inline bool guest_cpuid_has_mpx(struct kvm_vcpu *vcpu)

{

	struct kvm_cpuid_entry2 *best;



	best = kvm_find_cpuid_entry(vcpu, 7, 0);

	return best && (best->ebx & bit(X86_FEATURE_MPX));

}



static inline bool guest_cpuid_has_rdtscp(struct kvm_vcpu *vcpu)

{

	struct kvm_cpuid_entry2 *best;

arch/x86/kvm/vmx.c

+2 −2
Original line number Diff line number Diff line
@@ -2812,7 +2812,7 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
		msr_info->data = vmcs_readl(GUEST_SYSENTER_ESP);

		break;

	case MSR_IA32_BNDCFGS:

		if (!kvm_mpx_supported())

		if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu))

			return 1;

		msr_info->data = vmcs_read64(GUEST_BNDCFGS);

		break;
@@ -2889,7 +2889,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
		vmcs_writel(GUEST_SYSENTER_ESP, data);

		break;

	case MSR_IA32_BNDCFGS:

		if (!kvm_mpx_supported())

		if (!kvm_mpx_supported() || !guest_cpuid_has_mpx(vcpu))

			return 1;

		vmcs_write64(GUEST_BNDCFGS, data);

		break;