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perf events fixes

GIT PULL Merged Ingo Molnar 2 participants 2 messages Mar 17, 2024

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x86 perf events
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Ingo Molnar

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#0 lore raw

Linus,

Please pull the latest perf/urgent Git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2024-03-17

# HEAD: ad8c91282c95f801c37812d59d2d9eba6899b384 perf/x86/amd/core: Avoid register reset when CPU is dead

Two x86 PMU fixes:

- Work around AMD erratum to filter out bogus LBR stack entries

- Fix incorrect PMU reset that can result in warnings (or worse) during suspend/hibernation.

Thanks,

Ingo

------------------>
Sandipan Das (2):
perf/x86/amd/lbr: Discard erroneous branch entries perf/x86/amd/core: Avoid register reset when CPU is dead

 arch/x86/events/amd/core.c | 1 -
 arch/x86/events/amd/lbr.c  | 6 ++++--
 2 files changed, 4 insertions(+), 3 deletions(-)
arch/x86/events/amd/core.c +0 -1
index 69a3b02e50bb..aec16e581f5b 100644
@@ -604,7 +604,6 @@ static void amd_pmu_cpu_dead(int cpu)
 
 	kfree(cpuhw->lbr_sel);
 	cpuhw->lbr_sel = NULL;
-	amd_pmu_cpu_reset(cpu);
 
 	if (!x86_pmu.amd_nb_constraints)
 		return;
arch/x86/events/amd/lbr.c +4 -2
index eb31f850841a..4a1e600314d5 100644
@@ -173,9 +173,11 @@ void amd_pmu_lbr_read(void)
 
 		/*
 		 * Check if a branch has been logged; if valid = 0, spec = 0
-		 * then no branch was recorded
+		 * then no branch was recorded; if reserved = 1 then an
+		 * erroneous branch was recorded (see Erratum 1452)
 		 */
-		if (!entry.to.split.valid && !entry.to.split.spec)
+		if ((!entry.to.split.valid && !entry.to.split.spec) ||
+		    entry.to.split.reserved)
 			continue;
 
 		perf_clear_branch_entry_bitfields(br + out);
merge bot Merged
#1 lore raw
The pull request you sent on Sun, 17 Mar 2024 09:57:38 +0100:

The pull request you sent on Sun, 17 Mar 2024 09:57:38 +0100:

Quoted 1 line

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2024-03-17

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/b463a3c347df6f4d2d24f47c65716ae3166006e6

Thank you!

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