[PATCH V4 2/4] perf/x86/intel/uncore: Skip discovery table for offline dies

Zide Chen
2026-03-13T17:50:42Z

This warning can be triggered if NUMA is disabled and the system
boots with fewer CPUs than the number of CPUs in die 0.

WARNING: CPU: 9 PID: 7257 at uncore.c:1157 uncore_pci_pmu_register+0x136/0x160 [intel_uncore]

Currently, the discovery table continues to be parsed even if all CPUs
in the associated die are offline. This can lead to an array overflow
at "pmu->boxes[die] = box" in uncore_pci_pmu_register(), which may
trigger the warning above or cause other issues.

Reported-by: Steve Wahl <steve.wahl@hpe.com>
Tested-by: Steve Wahl <steve.wahl@hpe.com>
Fixes: edae1f06c2cd ("perf/x86/intel/uncore: Parse uncore discovery tables")
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
V2:
- Add the Tested-by tag
- Rebase onto perf/core (base commit: a491c02c2770)

V3:
- Remove the overly cautious WARN_ON()

V4:
- Add Reviewed-by tag.
---
arch/x86/events/intel/uncore_discovery.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
index 6a4e892cd525..749db3649f8f 100644
--- a/arch/x86/events/intel/uncore_discovery.c
+++ b/arch/x86/events/intel/uncore_discovery.c
@@ -371,7 +371,7 @@ static bool uncore_discovery_pci(struct uncore_discovery_domain *domain)
(val & UNCORE_DISCOVERY_DVSEC2_BIR_MASK) * UNCORE_DISCOVERY_BIR_STEP;

die = get_device_die_id(dev);
- if (die < 0)
+ if ((die < 0) || (die >= uncore_max_dies()))
continue;

parse_discovery_table(domain, dev, die, bar_offset, &parsed);
--
2.53.0