From cc8a853c2d5fe7e035c44fa18d3d9764fe220722 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Tue, 5 Sep 2023 06:42:48 -0700 Subject: [PATCH] perf/x86/uncore: Correct the number of CHAs on EMR commit 6f7f984fa85b305799076a1bcec941b9377587de upstream. Starting from SPR, the basic uncore PMON information is retrieved from the discovery table (resides in an MMIO space populated by BIOS). It is called the discovery method. The existing value of the type->num_boxes is from the discovery table. On some SPR variants, there is a firmware bug that makes the value from the discovery table incorrect. We use the value from the SPR_MSR_UNC_CBO_CONFIG MSR to replace the one from the discovery table: 38776cc45eb7 ("perf/x86/uncore: Correct the number of CHAs on SPR") Unfortunately, the SPR_MSR_UNC_CBO_CONFIG isn't available for the EMR XCC (Always returns 0), but the above firmware bug doesn't impact the EMR XCC. Don't let the value from the MSR replace the existing value from the discovery table. Fixes: 38776cc45eb7 ("perf/x86/uncore: Correct the number of CHAs on SPR") Reported-by: Stephane Eranian Reported-by: Yunying Sun Signed-off-by: Kan Liang Signed-off-by: Ingo Molnar Tested-by: Yunying Sun Link: https://lore.kernel.org/r/20230905134248.496114-1-kan.liang@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/events/intel/uncore_snbep.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c index 935081ddf60b..9b5859812f4f 100644 --- a/arch/x86/events/intel/uncore_snbep.c +++ b/arch/x86/events/intel/uncore_snbep.c @@ -6078,8 +6078,18 @@ 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); }