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Date: Tue, 5 Mar 2024 07:59:37 +0000
From: Conor Dooley <conor.dooley@microchip.com>
To: Anup Patel <apatel@ventanamicro.com>
CC: =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn@kernel.org>, Conor Dooley
	<conor@kernel.org>, Alexandre Ghiti <alexghiti@rivosinc.com>, Anup Patel
	<anup@brainfault.org>, Paul Walmsley <paul.walmsley@sifive.com>, Palmer
 Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, Andrea Parri
	<andrea@rivosinc.com>, Samuel Holland <samuel.holland@sifive.com>, Steven
 Rostedt <rostedt@goodmis.org>, Masami Hiramatsu <mhiramat@kernel.org>, Mark
 Rutland <mark.rutland@arm.com>, <linux-riscv@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <linux-trace-kernel@vger.kernel.org>,
	=?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn@rivosinc.com>, Andrea Parri
	<parri.andrea@gmail.com>
Subject: Re: [PATCH v3 2/2] riscv: Fix text patching when IPI are used
Message-ID: <20240305-sarcasm-ending-0f7946490aea@wendy>
References: <20240229121056.203419-1-alexghiti@rivosinc.com>
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On Tue, Mar 05, 2024 at 08:33:30AM +0530, Anup Patel wrote:
> On Tue, Mar 5, 2024 at 1:54=E2=80=AFAM Bj=C3=B6rn T=C3=B6pel <bjorn@kerne=
l.org> wrote:
> >
> > Conor Dooley <conor@kernel.org> writes:
> >
> > > On Thu, Feb 29, 2024 at 01:10:56PM +0100, Alexandre Ghiti wrote:
> > >> For now, we use stop_machine() to patch the text and when we use IPI=
s for
> > >> remote icache flushes (which is emitted in patch_text_nosync()), the=
 system
> > >> hangs.
> > >>
> > >> So instead, make sure every CPU executes the stop_machine() patching
> > >> function and emit a local icache flush there.
> > >>
> > >> Co-developed-by: Bj=C3=B6rn T=C3=B6pel <bjorn@rivosinc.com>
> > >> Signed-off-by: Bj=C3=B6rn T=C3=B6pel <bjorn@rivosinc.com>
> > >> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> > >> Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
> > >
> > > What commit does this fix?
> >
> > Hmm. The bug is exposed when the AIA IPI are introduced, and used
> > (instead of the firmware-based).
> >
> > I'm not sure this is something we'd like backported, but rather a
> > prerequisite to AIA.
> >
> > @Anup @Alex WDYT?
> >
>=20
> The current text patching never considered IPIs being injected
> directly in S-mode from hart to another so we are seeing this
> issue now with AIA IPIs.
>=20
> We certainly don't need to backport this fix since it's more
> of a preparatory fix for AIA IPIs.

Whether or not this is backportable, if it fixes a bug, it should get
a Fixes: tag for the commit that it fixes. Fixes: isn't "the backport"
tag, cc: stable is.

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