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

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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
This commit is contained in:
Zide Chen
2026-06-02 07:49:07 -07:00
committed by Peter Zijlstra
parent ce044cfb7a
commit 2aa7dacf8a
2 changed files with 8 additions and 3 deletions
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2
arch/x86/events/intel/uncore.c
View File

@@ -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) {

9
arch/x86/events/intel/uncore_snbep.c
View File

@@ -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;