Received-SPF: pass (google.com: domain of linux-kernel+bounces-194994-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Precedence: bulk
MIME-Version: 1.0
References: <20240222094006.1030709-1-apatel@ventanamicro.com>
 <20240222094006.1030709-2-apatel@ventanamicro.com> <CAMuHMdVYFFR7K5SbHBLY-JHhb7YpgGMS_hnRWm8H0KD-wBo+4A@mail.gmail.com>
 <11b3de44-522b-4638-987c-2ca132e84936@sifive.com>
In-Reply-To: <11b3de44-522b-4638-987c-2ca132e84936@sifive.com>
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Thu, 30 May 2024 09:06:54 +0200
Message-ID: <CAMuHMdV5jcbiHzYx=nqFHLLZ96u614zksSB5Vi9FVaOb_YMeiQ@mail.gmail.com>
Subject: Re: [PATCH v14 01/18] irqchip/sifive-plic: Convert PLIC driver into a
 platform driver
To: Samuel Holland <samuel.holland@sifive.com>
Cc: Anup Patel <apatel@ventanamicro.com>, devicetree@vger.kernel.org, 
	Conor Dooley <conor+dt@kernel.org>, Emil Renner Berthing <kernel@esmil.dk>, 
	Saravana Kannan <saravanak@google.com>, Marc Zyngier <maz@kernel.org>, Anup Patel <anup@brainfault.org>, 
	Atish Patra <atishp@atishpatra.org>, linux-kernel@vger.kernel.org, 
	=?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>, 
	Rob Herring <robh+dt@kernel.org>, Palmer Dabbelt <palmer@dabbelt.com>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, 
	Paul Walmsley <paul.walmsley@sifive.com>, Thomas Gleixner <tglx@linutronix.de>, 
	Frank Rowand <frowand.list@gmail.com>, linux-riscv@lists.infradead.org, 
	linux-arm-kernel@lists.infradead.org, Andrew Jones <ajones@ventanamicro.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hi Samuel,

On Thu, May 30, 2024 at 12:04=E2=80=AFAM Samuel Holland
<samuel.holland@sifive.com> wrote:
> On 2024-05-29 9:22 AM, Geert Uytterhoeven wrote:
> > On Thu, Feb 22, 2024 at 10:41=E2=80=AFAM Anup Patel <apatel@ventanamicr=
o.com> wrote:
> >> The PLIC driver does not require very early initialization so convert
> >> it into a platform driver.
> >>
> >> After conversion, the PLIC driver is probed after CPUs are brought-up
> >> so setup cpuhp state after context handler of all online CPUs are
> >> initialized otherwise PLIC driver crashes for platforms with multiple
> >> PLIC instances.
> >>
> >> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> >
> > Thanks for your patch, which is now commit 8ec99b033147ef3b
> > ("irqchip/sifive-plic: Convert PLIC driver into a platform
> > driver") in v6.9.
> >
> > It looks like this conversion is causing issues on BeagleV Starlight
> > Beta.  After updating esmil/visionfive to v6.10-rc1, the kernel usually
> > fails to boot. Adding "earlycon keep_bootcon" reveals these differences=
:
> >
> > -riscv-plic c000000.interrupt-controller: mapped 133 interrupts with 2
> > handlers for 4 contexts.
> > +------------[ cut here ]------------
> > +WARNING: CPU: 0 PID: 1 at drivers/irqchip/irq-sifive-plic.c:373

> > +Unable to handle kernel NULL pointer dereference at virtual address

> The fact that you hit the warning indicates that plic_handle_irq() was ca=
lled
> before handler->present was set. Previously the PLIC driver was probed ve=
ry
> early, so it is unlikely that some peripheral already had a pending inter=
rupt.
> Now, while platform device drivers would not yet be able to request inter=
rupts
> (because the irqdomain is not registered yet), they could have programmed=
 the
> hardware in a way that generates an interrupt. If that interrupt was enab=
led at
> the PLIC (e.g. by the bootloader), then we could expect plic_handle_irq()=
 to be
> called as soon as irq_set_chained_handler() is called.
>
> So the fix is to not call irq_set_chained_handler() until after the handl=
ers are
> completely set up.
>
> I've sent a patch doing this:
> https://lore.kernel.org/linux-riscv/20240529215458.937817-1-samuel.hollan=
d@sifive.com/

Thanks, that fixed the issue!

Gr{oetje,eeting}s,

                        Geert

--=20
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k=
org

In personal conversations with technical people, I call myself a hacker. Bu=
t
when I'm talking to journalists I just say "programmer" or something like t=
hat.
                                -- Linus Torvalds