diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2026-03-11 21:29:14 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-02 13:25:13 +0200 |
| commit | 8f5070236c87b5a99e9f34e22af82740437a331d (patch) | |
| tree | 694847727c3905bcaec62e1a7adeb842e491a09e /arch | |
| parent | de641ea08f8fff6906e169d2576c2ac54e562fbb (diff) | |
x86/perf: Make sure to program the counter value for stopped events on migration
[ Upstream commit f1cac6ac62d28a9a57b17f51ac5795bf250c12d3 ]
Both Mi Dapeng and Ian Rogers noted that not everything that sets HES_STOPPED
is required to EF_UPDATE. Specifically the 'step 1' loop of rescheduling
explicitly does EF_UPDATE to ensure the counter value is read.
However, then 'step 2' simply leaves the new counter uninitialized when
HES_STOPPED, even though, as noted above, the thing that stopped them might not
be aware it needs to EF_RELOAD -- since it didn't EF_UPDATE on stop.
One such location that is affected is throttling, throttle does pmu->stop(, 0);
and unthrottle does pmu->start(, 0); possibly restarting an uninitialized counter.
Fixes: a4eaf7f14675 ("perf: Rework the PMU methods")
Reported-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Reported-by: Ian Rogers <irogers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://patch.msgid.link/20260311204035.GX606826@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/events/core.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 818de24921a4..7a6b15b0f1c6 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -1371,8 +1371,10 @@ static void x86_pmu_enable(struct pmu *pmu) cpuc->events[hwc->idx] = event; - if (hwc->state & PERF_HES_ARCH) + if (hwc->state & PERF_HES_ARCH) { + static_call(x86_pmu_set_period)(event); continue; + } /* * if cpuc->enabled = 0, then no wrmsr as |