From mboxrd@z Thu Jan 1 00:00:00 1970 From: wei@redhat.com (Wei Huang) Date: Wed, 24 May 2017 09:36:41 -0500 Subject: [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off Message-ID: <1495636601-14726-1-git-send-email-wei@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 --- drivers/perf/arm_pmu_acpi.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c index 34c862f..d6bb75d 100644 --- a/drivers/perf/arm_pmu_acpi.c +++ b/drivers/perf/arm_pmu_acpi.c @@ -29,6 +29,9 @@ static int arm_pmu_acpi_register_irq(int cpu) return -EINVAL; gsi = gicc->performance_interrupt; + if (!gsi) + return 0; + if (gicc->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE) trigger = ACPI_EDGE_SENSITIVE; else @@ -58,7 +61,8 @@ static void arm_pmu_acpi_unregister_irq(int cpu) return; gsi = gicc->performance_interrupt; - acpi_unregister_gsi(gsi); + if (gsi) + acpi_unregister_gsi(gsi); } static int arm_pmu_acpi_parse_irqs(void) -- 2.7.4