This is a note to let you know that I've just added the patch titled
perf/x86/amd/uncore: Avoid PMU registration if counters are unavailable
to the 6.10-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:
perf-x86-amd-uncore-avoid-pmu-registration-if-counte.patch
and it can be found in the queue-6.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d3275e8a76be84b2edb4ab540ef321fdeae21eff
Author: Sandipan Das <sandipan.das@xxxxxxx>
Date: Wed Jun 26 13:14:04 2024 +0530
perf/x86/amd/uncore: Avoid PMU registration if counters are unavailable
[ Upstream commit f997e208b6c96858a2f6c0855debfbdb9b52f131 ]
X86_FEATURE_PERFCTR_NB and X86_FEATURE_PERFCTR_LLC are derived from
CPUID leaf 0x80000001 ECX bits 24 and 28 respectively and denote the
availability of DF and L3 counters. When these bits are not set, the
corresponding PMUs have no counters and hence, should not be registered.
Fixes: 07888daa056e ("perf/x86/amd/uncore: Move discovery and registration")
Signed-off-by: Sandipan Das <sandipan.das@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20240626074404.1044230-1-sandipan.das@xxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index 4ccb8fa483e61..b78e05ab4a737 100644
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -654,17 +654,20 @@ int amd_uncore_df_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
{
struct attribute **df_attr = amd_uncore_df_format_attr;
struct amd_uncore_pmu *pmu;
+ int num_counters;
/* Run just once */
if (uncore->init_done)
return amd_uncore_ctx_init(uncore, cpu);
+ num_counters = amd_uncore_ctx_num_pmcs(uncore, cpu);
+ if (!num_counters)
+ goto done;
+
/* No grouping, single instance for a system */
uncore->pmus = kzalloc(sizeof(*uncore->pmus), GFP_KERNEL);
- if (!uncore->pmus) {
- uncore->num_pmus = 0;
+ if (!uncore->pmus)
goto done;
- }
/*
* For Family 17h and above, the Northbridge counters are repurposed
@@ -674,7 +677,7 @@ int amd_uncore_df_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
pmu = &uncore->pmus[0];
strscpy(pmu->name, boot_cpu_data.x86 >= 0x17 ? "amd_df" : "amd_nb",
sizeof(pmu->name));
- pmu->num_counters = amd_uncore_ctx_num_pmcs(uncore, cpu);
+ pmu->num_counters = num_counters;
pmu->msr_base = MSR_F15H_NB_PERF_CTL;
pmu->rdpmc_base = RDPMC_BASE_NB;
pmu->group = amd_uncore_ctx_gid(uncore, cpu);
@@ -785,17 +788,20 @@ int amd_uncore_l3_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
{
struct attribute **l3_attr = amd_uncore_l3_format_attr;
struct amd_uncore_pmu *pmu;
+ int num_counters;
/* Run just once */
if (uncore->init_done)
return amd_uncore_ctx_init(uncore, cpu);
+ num_counters = amd_uncore_ctx_num_pmcs(uncore, cpu);
+ if (!num_counters)
+ goto done;
+
/* No grouping, single instance for a system */
uncore->pmus = kzalloc(sizeof(*uncore->pmus), GFP_KERNEL);
- if (!uncore->pmus) {
- uncore->num_pmus = 0;
+ if (!uncore->pmus)
goto done;
- }
/*
* For Family 17h and above, L3 cache counters are available instead
@@ -805,7 +811,7 @@ int amd_uncore_l3_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
pmu = &uncore->pmus[0];
strscpy(pmu->name, boot_cpu_data.x86 >= 0x17 ? "amd_l3" : "amd_l2",
sizeof(pmu->name));
- pmu->num_counters = amd_uncore_ctx_num_pmcs(uncore, cpu);
+ pmu->num_counters = num_counters;
pmu->msr_base = MSR_F16H_L2I_PERF_CTL;
pmu->rdpmc_base = RDPMC_BASE_LLC;
pmu->group = amd_uncore_ctx_gid(uncore, cpu);
