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Miscellaneous perf fixes: 

- Fix a PMU driver crash on AMD EPYC systems, caused by
    a race condition in x86_pmu_enable()
 
  - Fix a possible counter-initialization bug in x86_pmu_enable()
 
  - Fix a counter inheritance bug in inherit_event() and
    __perf_event_read()
 
  - Fix an Intel PMU driver branch constraints handling bug
    found by UBSAN
 
  - Fix the Intel PMU driver's new Off-Module Response (OMR)
    support code for Diamond Rapids / Nova lake, to fix a snoop
    information parsing bug
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-urgent-2026-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Ingo Molnar:

 - Fix a PMU driver crash on AMD EPYC systems, caused by
   a race condition in x86_pmu_enable()

 - Fix a possible counter-initialization bug in x86_pmu_enable()

 - Fix a counter inheritance bug in inherit_event() and
   __perf_event_read()

 - Fix an Intel PMU driver branch constraints handling bug
   found by UBSAN

 - Fix the Intel PMU driver's new Off-Module Response (OMR)
   support code for Diamond Rapids / Nova lake, to fix a snoop
   information parsing bug

* tag 'perf-urgent-2026-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel: Fix OMR snoop information parsing issues
  perf/x86/intel: Add missing branch counters constraint apply
  perf: Make sure to use pmu_ctx->pmu for groups
  x86/perf: Make sure to program the counter value for stopped events on migration
  perf/x86: Move event pointer setup earlier in x86_pmu_enable()
This commit is contained in:
Linus Torvalds 2026-03-22 10:31:51 -07:00
parent dea622e183 e7fcc54524
commit ebfd9b7af2
4 changed files with 41 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/x86/events/core.c
View File

@ -1372,14 +1372,17 @@ static void x86_pmu_enable(struct pmu *pmu)
else if (i < n_running)
continue;
if (hwc->state & PERF_HES_ARCH)
cpuc->events[hwc->idx] = event;
if (hwc->state & PERF_HES_ARCH) {
static_call(x86_pmu_set_period)(event);
continue;
}
/*
* if cpuc->enabled = 0, then no wrmsr as
* per x86_pmu_enable_event()
*/
cpuc->events[hwc->idx] = event;
x86_pmu_start(event, PERF_EF_RELOAD);
}
cpuc->n_added = 0;

31
arch/x86/events/intel/core.c
View File

@ -4628,6 +4628,19 @@ static inline void intel_pmu_set_acr_caused_constr(struct perf_event *event,
event->hw.dyn_constraint &= hybrid(event->pmu, acr_cause_mask64);
}
static inline int intel_set_branch_counter_constr(struct perf_event *event,
int *num)
{
if (branch_sample_call_stack(event))
return -EINVAL;
if (branch_sample_counters(event)) {
(*num)++;
event->hw.dyn_constraint &= x86_pmu.lbr_counters;
}
return 0;
}
static int intel_pmu_hw_config(struct perf_event *event)
{
int ret = x86_pmu_hw_config(event);
@ -4698,21 +4711,19 @@ static int intel_pmu_hw_config(struct perf_event *event)
* group, which requires the extra space to store the counters.
*/
leader = event->group_leader;
if (branch_sample_call_stack(leader))
if (intel_set_branch_counter_constr(leader, &num))
return -EINVAL;
if (branch_sample_counters(leader)) {
num++;
leader->hw.dyn_constraint &= x86_pmu.lbr_counters;
}
leader->hw.flags |= PERF_X86_EVENT_BRANCH_COUNTERS;
for_each_sibling_event(sibling, leader) {
if (branch_sample_call_stack(sibling))
if (intel_set_branch_counter_constr(sibling, &num))
return -EINVAL;
}
/* event isn't installed as a sibling yet. */
if (event != leader) {
if (intel_set_branch_counter_constr(event, &num))
return -EINVAL;
if (branch_sample_counters(sibling)) {
num++;
sibling->hw.dyn_constraint &= x86_pmu.lbr_counters;
}
}
if (num > fls(x86_pmu.lbr_counters))

11
arch/x86/events/intel/ds.c
View File

@ -345,12 +345,12 @@ static u64 parse_omr_data_source(u8 dse)
if (omr.omr_remote)
val |= REM;
val |= omr.omr_hitm ? P(SNOOP, HITM) : P(SNOOP, HIT);
if (omr.omr_source == 0x2) {
u8 snoop = omr.omr_snoop | omr.omr_promoted;
u8 snoop = omr.omr_snoop | (omr.omr_promoted << 1);
if (snoop == 0x0)
if (omr.omr_hitm)
val |= P(SNOOP, HITM);
else if (snoop == 0x0)
val |= P(SNOOP, NA);
else if (snoop == 0x1)
val |= P(SNOOP, MISS);
@ -359,7 +359,10 @@ static u64 parse_omr_data_source(u8 dse)
else if (snoop == 0x3)
val |= P(SNOOP, NONE);
} else if (omr.omr_source > 0x2 && omr.omr_source < 0x7) {
val |= omr.omr_hitm ? P(SNOOP, HITM) : P(SNOOP, HIT);
val |= omr.omr_snoop ? P(SNOOPX, FWD) : 0;
} else {
val |= P(SNOOP, NONE);
}
return val;

19
kernel/events/core.c
View File

@ -4813,7 +4813,7 @@ static void __perf_event_read(void *info)
struct perf_event *sub, *event = data->event;
struct perf_event_context *ctx = event->ctx;
struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
struct pmu *pmu = event->pmu;
struct pmu *pmu;
/*
* If this is a task context, we need to check whether it is
@ -4825,7 +4825,7 @@ static void __perf_event_read(void *info)
if (ctx->task && cpuctx->task_ctx != ctx)
return;
raw_spin_lock(&ctx->lock);
guard(raw_spinlock)(&ctx->lock);
ctx_time_update_event(ctx, event);
perf_event_update_time(event);
@ -4833,25 +4833,22 @@ static void __perf_event_read(void *info)
perf_event_update_sibling_time(event);
if (event->state != PERF_EVENT_STATE_ACTIVE)
goto unlock;
return;
if (!data->group) {
pmu->read(event);
perf_pmu_read(event);
data->ret = 0;
goto unlock;
return;
}
pmu = event->pmu_ctx->pmu;
pmu->start_txn(pmu, PERF_PMU_TXN_READ);
pmu->read(event);
perf_pmu_read(event);
for_each_sibling_event(sub, event)
perf_pmu_read(sub);
data->ret = pmu->commit_txn(pmu);
unlock:
raw_spin_unlock(&ctx->lock);
}
static inline u64 perf_event_count(struct perf_event *event, bool self)
@ -14744,7 +14741,7 @@ inherit_event(struct perf_event *parent_event,
get_ctx(child_ctx);
child_event->ctx = child_ctx;
pmu_ctx = find_get_pmu_context(child_event->pmu, child_ctx, child_event);
pmu_ctx = find_get_pmu_context(parent_event->pmu_ctx->pmu, child_ctx, child_event);
if (IS_ERR(pmu_ctx)) {
free_event(child_event);
return ERR_CAST(pmu_ctx);