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From: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>
To: Conor Dooley <conor@kernel.org>, Alexandre Ghiti
 <alexghiti@rivosinc.com>, Anup Patel <anup@brainfault.org>
Cc: 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,
 =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@rivosinc.com>, Andrea Parri
 <parri.andrea@gmail.com>
Subject: Re: [PATCH v3 2/2] riscv: Fix text patching when IPI are used
In-Reply-To: <20240304-makeshift-bakeshop-26c9611de1a3@spud>
References: <20240229121056.203419-1-alexghiti@rivosinc.com>
 <20240229121056.203419-3-alexghiti@rivosinc.com>
 <20240304-makeshift-bakeshop-26c9611de1a3@spud>
Date: Mon, 04 Mar 2024 21:24:09 +0100
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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 IPIs for
>> remote icache flushes (which is emitted in patch_text_nosync()), the sys=
tem
>> hangs.
>>=20
>> So instead, make sure every CPU executes the stop_machine() patching
>> function and emit a local icache flush there.
>>=20
>> 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?