From 477c50e8dc1c7b5004e099b8b74ca8b70be2f4fd Mon Sep 17 00:00:00 2001 From: Wei Huang Date: Tue, 30 May 2017 11:56:22 +0100 Subject: [PATCH] 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] [] enable_percpu_irq+0xdc/0xe4 [ 4.071192] [] arm_perf_starting_cpu+0x108/0x10c [ 4.072200] [] cpuhp_invoke_callback+0x14c/0x4ac [ 4.073210] [] cpuhp_thread_fun+0xd4/0x11c [ 4.074132] [] smpboot_thread_fn+0x1b4/0x1c4 [ 4.075081] [] kthread+0x10c/0x138 [ 4.075921] [] 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 [will: add comment justifying deviation from ACPI spec, removed redundant hunk] Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas --- drivers/perf/arm_pmu_acpi.c | 11 +++++++++++ 1 file changed, 11 insertions(+) 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