This is a note to let you know that I've just added the patch titled
kvm: x86: Guest BNDCFGS requires guest MPX support
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-guest-bndcfgs-requires-guest-mpx-support.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4439af9f911ae0243ffe4e2dfc12bace49605d8b Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@xxxxxxxxxx>
Date: Wed, 24 May 2017 10:49:25 -0700
Subject: kvm: x86: Guest BNDCFGS requires guest MPX support
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From: Jim Mattson <jmattson@xxxxxxxxxx>
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: 0dd376e709975779 ("KVM: x86: add MSR_IA32_BNDCFGS to msrs_to_save")
Change-Id: I3ad7c01bda616715137ceac878f3fa7e66b6b387
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/cpuid.h | 8 ++++++++
arch/x86/kvm/vmx.c | 4 ++--
2 files changed, 10 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -144,6 +144,14 @@ static inline bool guest_cpuid_has_rtm(s
return best && (best->ebx & bit(X86_FEATURE_RTM));
}
+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;
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2987,7 +2987,7 @@ static int vmx_get_msr(struct kvm_vcpu *
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;
@@ -3069,7 +3069,7 @@ static int vmx_set_msr(struct kvm_vcpu *
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;
Patches currently in stable-queue which might be from jmattson@xxxxxxxxxx are
queue-4.9/kvm-x86-guest-bndcfgs-requires-guest-mpx-support.patch
queue-4.9/kvm-vmx-check-value-written-to-ia32_bndcfgs.patch
queue-4.9/kvm-vmx-do-not-disable-intercepts-for-bndcfgs.patch