[PATCH 4.9 021/206] KVM: x86: reset MMU on KVM_SET_VCPU_EVENTS

From: Greg Kroah-Hartman
Date: Tue Jan 10 2017 - 08:44:17 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>

commit 6ef4e07ecd2db21025c446327ecf34414366498b upstream.

Otherwise, mismatch between the smm bit in hflags and the MMU role
can cause a NULL pointer dereference.

Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/x86/kvm/x86.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3036,6 +3036,8 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_
memset(&events->reserved, 0, sizeof(events->reserved));
}

+static void kvm_set_hflags(struct kvm_vcpu *vcpu, unsigned emul_flags);
+
static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
struct kvm_vcpu_events *events)
{
@@ -3072,10 +3074,13 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_e
vcpu->arch.apic->sipi_vector = events->sipi_vector;

if (events->flags & KVM_VCPUEVENT_VALID_SMM) {
+ u32 hflags = vcpu->arch.hflags;
if (events->smi.smm)
- vcpu->arch.hflags |= HF_SMM_MASK;
+ hflags |= HF_SMM_MASK;
else
- vcpu->arch.hflags &= ~HF_SMM_MASK;
+ hflags &= ~HF_SMM_MASK;
+ kvm_set_hflags(vcpu, hflags);
+
vcpu->arch.smi_pending = events->smi.pending;
if (events->smi.smm_inside_nmi)
vcpu->arch.hflags |= HF_SMM_INSIDE_NMI_MASK;