[PATCH V2 1/2] perf/x86/intel/uncore: Skip discovery table for offline dies

[Zide Chen]

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@xxxxxxx>
Tested-by: Steve Wahl <steve.wahl@xxxxxxx>
Fixes: edae1f06c2cd ("perf/x86/intel/uncore: Parse uncore discovery tables")
Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
---
V2:
- Add the Tested-by tag
- Rebase onto perf/core (base commit: a491c02c2770)

 arch/x86/events/intel/uncore.c           | 4 ++++
 arch/x86/events/intel/uncore_discovery.c | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 4684649109d9..c126a29ab729 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -1368,6 +1368,10 @@ static void uncore_pci_pmus_register(void)
 
 		for (node = rb_first(type->boxes); node; node = rb_next(node)) {
 			unit = rb_entry(node, struct intel_uncore_discovery_unit, node);
+
+			if (WARN_ON(unit->die >= uncore_max_dies()))
+				continue;
+
 			pdev = pci_get_domain_bus_and_slot(UNCORE_DISCOVERY_PCI_DOMAIN(unit->addr),
 							   UNCORE_DISCOVERY_PCI_BUS(unit->addr),
 							   UNCORE_DISCOVERY_PCI_DEVFN(unit->addr));
diff --git a/arch/x86/events/intel/uncore_discovery.c b/arch/x86/events/intel/uncore_discovery.c
index b46575254dbe..0e414cecb6f2 100644
--- a/arch/x86/events/intel/uncore_discovery.c
+++ b/arch/x86/events/intel/uncore_discovery.c
@@ -366,7 +366,7 @@ 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);
-- 
2.52.0