[patch 25/48] KVM: Make EFER reads safe when EFER does not exist

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Avi Kivity <avi@xxxxxxxxxx>

(cherry picked from commit e286e86e6d2042d67d09244aa0e05ffef75c9d54)

Some processors don't have EFER; don't oops if userspace wants us to
read EFER when we check NX.

Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 arch/x86/kvm/x86.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -983,9 +983,9 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *
 
 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;
 }
 


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