KVM: Make EFER reads safe when EFER does not exist
Some processors don't have EFER; don't oops if userspace wants us to
read EFER when we check NX.
Cc: stable@kernel.org
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 834a7bf..49079a4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1121,9 +1121,9 @@
static int is_efer_nx(void)
{
- u64 efer;
+ unsigned long long efer = 0;
- rdmsrl(MSR_EFER, efer);
+ rdmsrl_safe(MSR_EFER, &efer);
return efer & EFER_NX;
}