* [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off
@ 2017-05-24 14:36 Wei Huang
2017-05-25 15:28 ` Will Deacon
0 siblings, 1 reply; 4+ messages in thread
From: Wei Huang @ 2017-05-24 14:36 UTC (permalink / raw)
To: linux-arm-kernel
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;
+
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off
2017-05-24 14:36 [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off Wei Huang
@ 2017-05-25 15:28 ` Will Deacon
2017-05-25 15:49 ` Wei Huang
0 siblings, 1 reply; 4+ messages in thread
From: Will Deacon @ 2017-05-25 15:28 UTC (permalink / raw)
To: linux-arm-kernel
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off
2017-05-25 15:28 ` Will Deacon
@ 2017-05-25 15:49 ` Wei Huang
2017-05-25 15:50 ` Will Deacon
0 siblings, 1 reply; 4+ messages in thread
From: Wei Huang @ 2017-05-25 15:49 UTC (permalink / raw)
To: linux-arm-kernel
On 05/25/2017 10:28 AM, Will Deacon wrote:
> 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"...
Yes, returning 0 here and dmesg prints out "No ACPI PMU IRQ for CPU" is
acceptable.
>
>> 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.
I am OK to drop it. It was added just to be cautious... Do you need
another version from me or you will remove this hunk?
>
> Will
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off
2017-05-25 15:49 ` Wei Huang
@ 2017-05-25 15:50 ` Will Deacon
0 siblings, 0 replies; 4+ messages in thread
From: Will Deacon @ 2017-05-25 15:50 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, May 25, 2017 at 10:49:49AM -0500, Wei Huang wrote:
> On 05/25/2017 10:28 AM, Will Deacon wrote:
> > On Wed, May 24, 2017 at 09:36:41AM -0500, Wei Huang wrote:
> >> 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.
>
> I am OK to drop it. It was added just to be cautious... Do you need
> another version from me or you will remove this hunk?
I can drop this hunk, no need to repost.
Thanks,
Will
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-05-24 14:36 [PATCH 1/1] drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off Wei Huang
2017-05-25 15:28 ` Will Deacon
2017-05-25 15:49 ` Wei Huang
2017-05-25 15:50 ` Will Deacon
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