[tip: perf/urgent] perf/x86/intel/uncore: Skip discovery table for offline dies

["tip-bot2 for Zide Chen" <tip-bot2@linutronix.de>]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     7b568e9eba2fad89a696f22f0413d44cf4a1f892
Gitweb:        https://git.kernel.org/tip/7b568e9eba2fad89a696f22f0413d44cf4a1f892
Author:        Zide Chen <zide.chen@intel.com>
AuthorDate:    Fri, 13 Mar 2026 10:40:48 -07:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 07 Apr 2026 09:05:29 +02:00

perf/x86/intel/uncore: Skip discovery table for offline dies

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.

Fixes: edae1f06c2cd ("perf/x86/intel/uncore: Parse uncore discovery tables")
Reported-by: Steve Wahl <steve.wahl@hpe.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://patch.msgid.link/20260313174050.171704-3-zide.chen@intel.com
---
 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 427939b..583cbd0 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);