2019-07-18 05:39:47

by Like Xu

Subject: [PATCH v2] KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed

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 <[email protected]>
Signed-off-by: Like Xu <[email protected]>
---
arch/x86/kvm/pmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index aa5a2597305a..cedaa01ceb6f 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -131,8 +131,8 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
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;
}

--
2.21.0

2019-07-18 13:54:09

by Paolo Bonzini

Subject: Re: [PATCH v2] KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed

On 18/07/19 07:35, Like Xu wrote:
> 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 <[email protected]>
> Signed-off-by: Like Xu <[email protected]>
> ---
> arch/x86/kvm/pmu.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index aa5a2597305a..cedaa01ceb6f 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -131,8 +131,8 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
> 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;
> }
>
>

Queued, thanks.

Paolo