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authorWei Huang <wei@redhat.com>2017-05-30 11:56:22 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2017-05-30 12:40:03 +0100
commit477c50e8dc1c7b5004e099b8b74ca8b70be2f4fd (patch)
treebf2e1d1460f04943a576021b0209b243bfbc568e
parent717902cc93118119a6fce7765da6cf2786987418 (diff)
drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off
We saw perf IRQ init failures when running Linux kernel in an ACPI guest without PMU (i.e. pmu=off). This is because perf IRQ is not present when pmu=off, but arm_pmu_acpi still tries to register or unregister GSI. This patch addresses the problem by checking gicc->performance_interrupt. If it is 0, which is the value set by qemu when pmu=off, we skip the IRQ register/unregister process. [ 4.069470] bc00: 0000000000040b00 ffff0000089db190 [ 4.070267] [<ffff000008134f80>] enable_percpu_irq+0xdc/0xe4 [ 4.071192] [<ffff000008667cc4>] arm_perf_starting_cpu+0x108/0x10c [ 4.072200] [<ffff0000080cbdd4>] cpuhp_invoke_callback+0x14c/0x4ac [ 4.073210] [<ffff0000080ccd3c>] cpuhp_thread_fun+0xd4/0x11c [ 4.074132] [<ffff0000080f1394>] smpboot_thread_fn+0x1b4/0x1c4 [ 4.075081] [<ffff0000080ec90c>] kthread+0x10c/0x138 [ 4.075921] [<ffff0000080833c0>] ret_from_fork+0x10/0x50 [ 4.076947] genirq: Setting trigger mode 4 for irq 43 failed (gic_set_type+0x0/0x74) Signed-off-by: Wei Huang <wei@redhat.com> [will: add comment justifying deviation from ACPI spec, removed redundant hunk] Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--drivers/perf/arm_pmu_acpi.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
index 34c862f213c7..0a9b78705ee8 100644
--- a/drivers/perf/arm_pmu_acpi.c
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -29,6 +29,17 @@ static int arm_pmu_acpi_register_irq(int cpu)
return -EINVAL;
gsi = gicc->performance_interrupt;
+
+ /*
+ * Per the ACPI spec, the MADT cannot describe a PMU that doesn't
+ * have an interrupt. QEMU advertises this by using a GSI of zero,
+ * which is not known to be valid on any hardware despite being
+ * valid per the spec. Take the pragmatic approach and reject a
+ * GSI of zero for now.
+ */
+ if (!gsi)
+ return 0;
+
if (gicc->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE)
trigger = ACPI_EDGE_SENSITIVE;
else