Messages in this thread | | | Date | Thu, 25 May 2017 16:28:14 +0100 | From | Will Deacon <> | Subject | Re: [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off |
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Hi Wei,
On Wed, May 24, 2017 at 09:36:41AM -0500, Wei Huang wrote: > 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> > --- > 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;
So a GSI of zero means we return an IRQ of zero, which correctly gets treated as "No ACPI PMU"...
> 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);
... but then I don't see how we can get here, so I'll drop this hunk.
Will
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