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perf events fix

GIT PULL Merged Ingo Molnar 2 participants 2 messages Sep 10, 2023

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x86 perf events
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Ingo Molnar

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Linus,

Please pull the latest perf/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2023-09-10

# HEAD: 6f7f984fa85b305799076a1bcec941b9377587de perf/x86/uncore: Correct the number of CHAs on EMR

Work around a firmware bug in the uncore PMU driver, affecting certain Intel systems.

Thanks,

Ingo

------------------>
Kan Liang (1):
perf/x86/uncore: Correct the number of CHAs on EMR

 arch/x86/events/intel/uncore_snbep.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)
arch/x86/events/intel/uncore_snbep.c +11 -1
index 4d349986f76a..8250f0f59c2b 100644
@@ -6474,8 +6474,18 @@ void spr_uncore_cpu_init(void)
 
 	type = uncore_find_type_by_id(uncore_msr_uncores, UNCORE_SPR_CHA);
 	if (type) {
+		/*
+		 * The value from the discovery table (stored in the type->num_boxes
+		 * of UNCORE_SPR_CHA) is incorrect on some SPR variants because of a
+		 * firmware bug. Using the value from SPR_MSR_UNC_CBO_CONFIG to replace it.
+		 */
 		rdmsrl(SPR_MSR_UNC_CBO_CONFIG, num_cbo);
-		type->num_boxes = num_cbo;
+		/*
+		 * The MSR doesn't work on the EMR XCC, but the firmware bug doesn't impact
+		 * the EMR XCC. Don't let the value from the MSR replace the existing value.
+		 */
+		if (num_cbo)
+			type->num_boxes = num_cbo;
 	}
 	spr_uncore_iio_free_running.num_boxes = uncore_type_max_boxes(uncore_msr_uncores, UNCORE_SPR_IIO);
 }
merge bot Merged
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The pull request you sent on Sun, 10 Sep 2023 18:20:51 +0200:

The pull request you sent on Sun, 10 Sep 2023 18:20:51 +0200:

Quoted 1 line

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2023-09-10

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/e79dbf03d87b2d9978d76ddc1c06424b07b215ad

Thank you!

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