From: Dirk Müller <dmueller@suse.com>
Date: Thu, 1 Oct 2015 11:43:42 +0000 (+0200)
Subject: Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS
X-Git-Tag: v3.16.35~1192
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0436b7e13971c9322aa5f7e3018d51162dd76ae5;p=thirdparty%2Fkernel%2Fstable.git

Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS

commit d2922422c48df93f3edff7d872ee4f3191fefb08 upstream.

The cpu feature flags are not ever going to change, so warning
everytime can cause a lot of kernel log spam
(in our case more than 10GB/hour).

The warning seems to only occur when nested virtualization is
enabled, so it's probably triggered by a KVM bug.  This is a
sensible and safe change anyway, and the KVM bug fix might not
be suitable for stable releases anyway.

Signed-off-by: Dirk Mueller <dmueller@suse.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 37e85d0a19408..539f233965f16 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -512,7 +512,7 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 
 	if (svm->vmcb->control.next_rip != 0) {
-		WARN_ON(!static_cpu_has(X86_FEATURE_NRIPS));
+		WARN_ON_ONCE(!static_cpu_has(X86_FEATURE_NRIPS));
 		svm->next_rip = svm->vmcb->control.next_rip;
 	}