From: Avi Kivity <avi@redhat.com>
Date: Sun, 3 May 2009 15:50:55 +0000 (+0300)
Subject: KVM: Make EFER reads safe when EFER does not exist
X-Git-Tag: v2.6.29.4~8
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=21616cb7a37a63b9f33ea2e45ab6d29910b43fd2;p=thirdparty%2Fkernel%2Fstable.git

KVM: Make EFER reads safe when EFER does not exist

commit e286e86e6d2042d67d09244aa0e05ffef75c9d54 upstream.

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@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 425423eff489d..92f0457ebe58b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1075,9 +1075,9 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *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;
 }