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SubjectRe: [PATCH] genirq/msi: Shutdown managed interrupts with unsatifiable affinities
On Mon, Mar 7, 2022 at 11:06 AM Marc Zyngier <maz@kernel.org> wrote:
>
> When booting with maxcpus=<small number>, interrupt controllers
> such as the GICv3 ITS may not be able to satisfy the affinity of
> some managed interrupts, as some of the HW resources are simply
> not available.
>
> In order to deal with this, do not try to activate such interrupt
> if there is no online CPU capable of handling it. Instead, place
> it in shutdown state. Once a capable CPU shows up, it will be
> activated.
>
> Reported-by: John Garry <john.garry@huawei.com>
> Reported-by: David Decotigny <ddecotig@google.com>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> kernel/irq/msi.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
> index 2bdfce5edafd..aa84ce84c2ec 100644
> --- a/kernel/irq/msi.c
> +++ b/kernel/irq/msi.c
> @@ -818,6 +818,18 @@ static int msi_init_virq(struct irq_domain *domain, int virq, unsigned int vflag
> irqd_clr_can_reserve(irqd);
> if (vflags & VIRQ_NOMASK_QUIRK)
> irqd_set_msi_nomask_quirk(irqd);
> +
> + /*
> + * If the interrupt is managed but no CPU is available
> + * to service it, shut it down until better times.
> + */
> + if ((vflags & VIRQ_ACTIVATE) &&
> + irqd_affinity_is_managed(irqd) &&
> + !cpumask_intersects(irq_data_get_affinity_mask(irqd),
> + cpu_online_mask)) {
> + irqd_set_managed_shutdown(irqd);
> + return 0;
> + }
> }
>
> if (!(vflags & VIRQ_ACTIVATE))
> --
> 2.30.2
>

Thanks! I tried that patch, and it worked for us.

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