Re: [PATCH v2 3/6] arm64: Mark the recheduling IPI as raw interrupt

Will Deacon
2020-12-10T15:17:41Z

On Tue, Nov 24, 2020 at 02:14:46PM +0000, Marc Zyngier wrote:
> Flag the rescheduling IPI as 'raw', making sure such interrupt
> skips both tick management and irqtime accounting.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/Kconfig | 1 +
> arch/arm64/kernel/smp.c | 4 ++++
> 2 files changed, 5 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1515f6f153a0..d18c2c15848d 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -108,6 +108,7 @@ config ARM64
> select GENERIC_EARLY_IOREMAP
> select GENERIC_IDLE_POLL_SETUP
> select GENERIC_IRQ_IPI
> + select ARCH_WANTS_IRQ_RAW
> select GENERIC_IRQ_MULTI_HANDLER
> select GENERIC_IRQ_PROBE
> select GENERIC_IRQ_SHOW
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 18e9727d3f64..bad51f7f7ffe 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -995,6 +995,10 @@ void __init set_smp_ipi_range(int ipi_base, int n)
>
> ipi_desc[i] = irq_to_desc(ipi_base + i);
> irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
> +
> + /* The recheduling IPI is special... */
> + if (i == IPI_RESCHEDULE)
> + __irq_modify_status(ipi_base + i, 0, IRQ_RAW, ~0);

Acked-by: Will Deacon <will@kernel.org>

Although this part isn't the controversial bit :)

Will