linux-kernel - Re: [PATCH 3.16 47/47] KVM: x86/vPMU: refine kvm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <220d8f2c1b299d2e71fdcf50b98286aae5b0c6f2.camel@perches.com>
Date:   Fri, 25 Oct 2019 12:05:43 -0700
From:   Joe Perches <joe@...ches.com>
To:     Ben Hutchings <ben@...adent.org.uk>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        Like Xu <like.xu@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH 3.16 47/47] KVM: x86/vPMU: refine kvm_pmu err msg when
 event creation failed

On Fri, 2019-10-25 at 19:03 +0100, Ben Hutchings wrote:
> 3.16.76-rc1 review patch.  If anyone has any objections, please let me know.

This seems more like an enhancement than a bug fix.

Is this really the type of patch that is appropriate
for stable?

> ------------------
> 
> From: Like Xu <like.xu@...ux.intel.com>
> 
> commit 6fc3977ccc5d3c22e851f2dce2d3ce2a0a843842 upstream.
> 
> If a perf_event creation fails due to any reason of the host perf
> subsystem, it has no chance to log the corresponding event for guest
> which may cause abnormal sampling data in guest result. In debug mode,
> this message helps to understand the state of vPMC and we may not
> limit the number of occurrences but not in a spamming style.
> 
> Suggested-by: Joe Perches <joe@...ches.com>
> Signed-off-by: Like Xu <like.xu@...ux.intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> [bwh: Backported to 3.16: adjust context]
> Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
> ---
>  arch/x86/kvm/pmu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -187,8 +187,8 @@ static void reprogram_counter(struct kvm
>  						 intr ? kvm_perf_overflow_intr :
>  						 kvm_perf_overflow, pmc);
>  	if (IS_ERR(event)) {
> -		printk_once("kvm: pmu event creation failed %ld\n",
> -				PTR_ERR(event));
> +		pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n",
> +			    PTR_ERR(event), pmc->idx);
>  		return;
>  	}
>  
>