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Tue, 11 Mar 2025 05:44:15 -0700 (PDT) Date: Tue, 11 Mar 2025 13:44:07 +0100 From: Andrea Parri To: =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= Cc: Andy Chiu , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, bjorn@rivosinc.com, puranjay12@gmail.com, alexghiti@rivosinc.com, yongxuan.wang@sifive.com, greentime.hu@sifive.com, nick.hu@sifive.com, nylon.chen@sifive.com, tommy.wu@sifive.com, eric.lin@sifive.com, viccent.chen@sifive.com, zong.li@sifive.com, samuel.holland@sifive.com Subject: Re: [PATCH v3 6/7] riscv: add a data fence for CMODX in the kernel mode Message-ID: References: <20241127172908.17149-1-andybnac@gmail.com> <20241127172908.17149-7-andybnac@gmail.com> <87ldtck8k0.fsf@all.your.base.are.belong.to.us> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ldtck8k0.fsf@all.your.base.are.belong.to.us> > FWIW, the for S-IMSIC the write is already writel(), so we'll have the > text patching and IPI ordered. Regardless, there's more than one flavor > of IPI on RISC-V! AFAIU, this writel() is intended to order the insertion (and the initialization) of the CSD object before the MMIO writes; so, the "right fix" seems to turn the "other flavors" into using a writel() or providing a similar ordering guarantee. As a bonus, such change should address/fix all current and future occurrences of the message-passing scenario in question (the patch addressed the occurrence in flush_icache_all(), but there appears to be a similar one in flush_icache_mm()). Or am I misunderstanding your previous comment? Andrea