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t=1789762542; bh=OAEsOLRukFLus0d8Tfr9V8PlCCQdG3TdiUlAGwmhXjA=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=K//zyog2V0U5XIgFvmnnIv4886FNdZhDLQofPIKBTWXzdsJ0WqbwVY1MECT0yYu4i 4ZqWxbUzkgZhfArlZn0Ohx4LFYwze/+QQeCZfTSuZe8bXffQM+TkOo1vajLxH7QWKH pCzk0jC946j9ZqV6KNZOaQ2HQrhA6m3AyVuiamOMb/3xqlTrQVp290o5zWsY95idWy G4mybv/5QF7JoFrCjTh9fQg/QiTBsGdTVOxOAnuaP9GraJEAjOSmEDR2ncBnMgtL/M +ED9/D/rGVUXvb46t+ZZKpA1vQI9jjyYFR8T2zFltuShDIyWw8pfajQO7Jxf92LGze zIJGv2d2yxv/w== From: sashiko-bot@kernel.org Subject: Re: [PATCH v9 08/13] PCI: Save and restore the ACS Control register Reply-To: sashiko-reviews@lists.linux.dev To: linux-mm@kvack.org, "David Matlack" , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: "Alex Williamson" , kexec@lists.infradead.org, "Jonathan Corbet" , "Mike Rapoport" , "Bjorn Helgaas" , "David Rientjes" , linux-pci@vger.kernel.org, "Lukas Wunner" , "Parav Pandit" , "Pratyush Yadav" , "Saeed Mahameed" , "Samiullah Khawaja" , "Shuah Khan" , "Vipin Sharma" , "Leon Romanovsky" , "Adithya Jayachandran" , "Jason Gunthorpe" , "William Tu" , "Josh Hilke" , "Yi Liu" , "Jacob Pan" , "Pasha Tatashin" , "Pranjal Shrivastava" , "Alexander Graf" , "Chris Li" , "Randy Dunlap" In-Reply-To: <20260918200640.887030-9-dmatlack@google.com> References: <20260918200640.887030-1-dmatlack@google.com> <20260918200640.887030-9-dmatlack@google.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 18 Sep 2026 20:15:40 +0000 Message-Id: <20260918201540.64B171F000FF@smtp.kernel.org> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1600A100002 X-Rspam-User: X-Stat-Signature: t1pmyp9qby8e1b7ip1ejfizxqbxk5dnu X-HE-Tag: 1789762542-41022 X-HE-Meta: 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 L7k1EEpg 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Save the ACS Control register in pci_save_state() and write it back > in pci_restore_state(), instead of recomputing the ACS controls from > scratch with pci_enable_acs(). >=20 > This makes ACS symmetric with the rest of a device's saved state. Today > pci_save_state() ignores ACS entirely and pci_restore_state() re-enables > the ACS controls from the kernel's current ACS policy. As a result, a > device can come out of a reset with different ACS controls than it went > in with, e.g. any controls programmed outside of pci_enable_acs() are > silently dropped. >=20 > pci_enable_acs() runs when a driver binds to a device > (pci_dma_configure()), i.e. after pci_bus_add_device() has already saved > the device's state. Refresh the saved ACS Control register there as > well, otherwise a subsequent reset would revert ACS back to the > configuration left behind by firmware. >=20 > Devices that rely on device-specific quirks to enable an ACS equivalent > keep that configuration outside of the ACS Control register, so keep > configuring ACS from scratch for them. Do the same for devices that have > no saved ACS state at all. >=20 > Reviewed-by: Bjorn Helgaas > Assisted-by: Claude:claude-opus-5 > Signed-off-by: David Matlack Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260918200640.8870= 30-1-dmatlack@google.com?part=3D8