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: kvm-86rc2~40
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7da2e3ba1ca8c2f8406f366c35d9c678354a76a6;p=users%2Fdwmw2%2Flinux.git

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 8b0d77707e16e..2d7082c708430 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1128,9 +1128,9 @@ 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;
 }