perf/x86/intel/uncore: Fix uncore_die_to_cpu() for offline dies

If the die is offline when uncore_die_to_cpu() is called, it silently
returns 0, which is misleading.  Return -1 in this case to indicate
that all CPUs on the die are offline and the caller can take care of
it accordingly.

Opportunistically, replace -EPERM with -ENODEV, as -ENODEV is
the appropriate error when no CPUs are online across all dies.

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>
Link: https://patch.msgid.link/20260602144908.263680-7-zide.chen@intel.com

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index 22256ded2d67d56b6cefc339704b629feb2490b0..4b3a1fa5b41b7de6323754307e980844f6d29e29 100644 (file)
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -91,7 +91,7 @@ int uncore_device_to_die(struct pci_dev *dev)
  */
 int uncore_die_to_cpu(int die)
 {
-       int res = 0, cpu;
+       int res = -1, cpu;
 
        for_each_online_cpu(cpu) {
                if (topology_logical_die_id(cpu) == die) {

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index 772b78237424ce5de6327749ac0892d954562297..334dc384b5b936e37feb0787e15d2f557155fcb0 100644 (file)
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -3772,12 +3772,17 @@ static void pmu_free_topology(struct intel_uncore_type *type)
 static int skx_pmu_get_topology(struct intel_uncore_type *type,
                                 int (*topology_cb)(struct intel_uncore_type*, int, int, u64))
 {
-       int die, ret = -EPERM;
+       int die, ret = -ENODEV;
        u64 cpu_bus_msr;
+       int cpu;
 
        cpus_read_lock();
        for (die = 0; die < uncore_max_dies(); die++) {
-               ret = skx_msr_cpu_bus_read(uncore_die_to_cpu(die), &cpu_bus_msr);
+               cpu = uncore_die_to_cpu(die);
+               if (cpu == -1)
+                       continue;
+
+               ret = skx_msr_cpu_bus_read(cpu, &cpu_bus_msr);
                if (ret)
                        break;