Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 29 Sep 2021 08:24:34 +0100
Message-ID: <87lf3fu9n1.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Pingfan Liu <kernelfans@gmail.com>
Cc:     linux-arm-kernel@lists.infradead.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Joey Gouly <joey.gouly@arm.com>,
        Sami Tolvanen <samitolvanen@google.com>,
        Julien Thierry <julien.thierry@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Yuichi Ito <ito-yuichi@fujitsu.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2 5/5] irqchip/GICv3: make reschedule-ipi light weight
In-Reply-To: <20210924132837.45994-6-kernelfans@gmail.com>
References: <20210924132837.45994-1-kernelfans@gmail.com>
        <20210924132837.45994-6-kernelfans@gmail.com>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue)
 FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1
 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

On Fri, 24 Sep 2021 14:28:37 +0100,
Pingfan Liu <kernelfans@gmail.com> wrote:
> 
> To achieve the light weight as
> DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_reschedule_ipi) on x86, it had
> better treat irqnr differently at the frontend. And let IPI_RESCHEDULE
> call __irq_enter_raw() instead of irq_enter_rcu().
> 
> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Joey Gouly <joey.gouly@arm.com>
> Cc: Sami Tolvanen <samitolvanen@google.com>
> Cc: Julien Thierry <julien.thierry@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
> Cc: linux-kernel@vger.kernel.org
> To: linux-arm-kernel@lists.infradead.org
> ---
>  drivers/irqchip/irq-gic-v3.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 906538fa8771..593d4539a209 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -709,6 +709,9 @@ static void gic_handle_nmi(struct pt_regs *regs)
>  		gic_deactivate_unhandled(irqnr);
>  }
>  
> +/* RESCHEDULE IPI hwirq nr is 0, and the only raw one */
> +static unsigned long raw_interrupt_mask = 1;

I'm afraid you have the wrong end of the stick. This isn't a GIC
property. This is an architecture decision, and only the architecture
can expose what they want.

	M.

-- 
Without deviation from the norm, progress is not possible.