[Patch v9 01/24] perf/x86: Fix two error-path and hybrid PMU guard issues

[Dapeng Mi]

Fix an NMI handler leak in init_hw_perf_events(). When PMU
initialization fails after register_nmi_handler(), the error path
exits without calling unregister_nmi_handler(), leaving a stale
NMI_LOCAL "PMI" handler registered. Add the missing call before
clearing x86_pmu state.

Also guard the hybrid PMU cpumask update in intel_pmu_cpu_dead()
with a check on x86_pmu.num_hybrid_pmus. Without this, hybrid_pmu()
may be called when the hybrid PMU array has not been allocated,
leading to an out-of-bounds access.

Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
 arch/x86/events/core.c       | 4 +++-
 arch/x86/events/intel/core.c | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index af0b67ffb43d..872d07a5fa80 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2219,7 +2219,7 @@ static int __init init_hw_perf_events(void)
 	err = cpuhp_setup_state(CPUHP_PERF_X86_PREPARE, "perf/x86:prepare",
 				x86_pmu_prepare_cpu, x86_pmu_dead_cpu);
 	if (err)
-		return err;
+		goto pmi_unregister;
 
 	err = cpuhp_setup_state(CPUHP_AP_PERF_X86_STARTING,
 				"perf/x86:starting", x86_pmu_starting_cpu,
@@ -2273,6 +2273,8 @@ static int __init init_hw_perf_events(void)
 	cpuhp_remove_state(CPUHP_AP_PERF_X86_STARTING);
 out:
 	cpuhp_remove_state(CPUHP_PERF_X86_PREPARE);
+pmi_unregister:
+	unregister_nmi_handler(NMI_LOCAL, "PMI");
 out_bad_pmu:
 	memset(&x86_pmu, 0, sizeof(x86_pmu));
 	return err;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index b39c6ce0efb5..b8a6382dbb82 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -6479,7 +6479,7 @@ static void intel_pmu_cpu_dead(int cpu)
 	release_arch_pebs_buf_on_cpu(cpu);
 	intel_cpuc_finish(cpuc);
 
-	if (is_hybrid() && cpuc->pmu)
+	if (is_hybrid() && x86_pmu.num_hybrid_pmus && cpuc->pmu)
 		cpumask_clear_cpu(cpu, &hybrid_pmu(cpuc->pmu)->supported_cpus);
 }
 
-- 
2.34.1