Patch "Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS" has been added to the 4.1-stable tree

Patch "Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS" has been added to the 4.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS

to the 4.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     use-warn_on_once-for-missing-x86_feature_nrips.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d2922422c48df93f3edff7d872ee4f3191fefb08 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dirk=20M=C3=BCller?= <dmueller@suse.com>
Date: Thu, 1 Oct 2015 13:43:42 +0200
Subject: Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS

From: =?UTF-8?q?Dirk=20M=C3=BCller?= <dmueller@suse.com>

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kvm/svm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -512,7 +512,7 @@ static void skip_emulated_instruction(st
 	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;
 	}
 


Patches currently in stable-queue which might be from dmueller@suse.com are

queue-4.1/use-warn_on_once-for-missing-x86_feature_nrips.patch