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SubjectRe: [PATCH] irqchip/gic-v3-its: Don't try to move a disabled irq
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Hi,

On 2020/5/29 9:55, Ali Saidi wrote:
> If an interrupt is disabled the ITS driver has sent a discard removing
> the DeviceID and EventID from the ITT. After this occurs it can't be
> moved to another collection with a MOVI and a command error occurs if
> attempted. Before issuing the MOVI command make sure that the IRQ isn't
> disabled and change the activate code to try and use the previous
> affinity.
>
> Signed-off-by: Ali Saidi <alisaidi@amazon.com>
> ---
> drivers/irqchip/irq-gic-v3-its.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 124251b0ccba..1235dd9a2fb2 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -1540,7 +1540,11 @@ static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
> /* don't set the affinity when the target cpu is same as current one */
> if (cpu != its_dev->event_map.col_map[id]) {
> target_col = &its_dev->its->collections[cpu];
> - its_send_movi(its_dev, target_col, id);
> +
> + /* If the IRQ is disabled a discard was sent so don't move */
> + if (!irqd_irq_disabled(d))
> + its_send_movi(its_dev, target_col, id);

It looks to me that if the IRQ is disabled, we mask the enable bit in
the corresponding LPI configuration table entry, but not sending DISCARD
to remove the DevID/EventID mapping. And moving a disabled LPI is
actually allowed by the GIC architecture, right?

> +
> its_dev->event_map.col_map[id] = cpu;
> irq_data_update_effective_affinity(d, cpumask_of(cpu));
> }
> @@ -3439,8 +3443,16 @@ static int its_irq_domain_activate(struct irq_domain *domain,
> if (its_dev->its->numa_node >= 0)
> cpu_mask = cpumask_of_node(its_dev->its->numa_node);
>
> - /* Bind the LPI to the first possible CPU */
> - cpu = cpumask_first_and(cpu_mask, cpu_online_mask);
> + /* If the cpu set to a different CPU that is still online use it */
> + cpu = its_dev->event_map.col_map[event];
> +
> + cpumask_and(cpu_mask, cpu_mask, cpu_online_mask);
> +
> + if (!cpumask_test_cpu(cpu, cpu_mask)) {
> + /* Bind the LPI to the first possible CPU */
> + cpu = cpumask_first(cpu_mask);
> + }

I'd like to know what actual problem you had seen and the way to
reproduce it :-)


Thanks,
Zenghui

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