[PATCH 4.19 213/271] KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed

From: Greg Kroah-Hartman
Date: Thu Jul 25 2019 - 11:03:02 EST

From: Like Xu <like.xu@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxx>
Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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
@@ -131,8 +131,8 @@ static void pmc_reprogram_counter(struct
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);