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[34.142.211.105]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a49858c123sm538411a91.3.2026.09.28.10.19.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 10:19:49 -0700 (PDT) Date: Mon, 28 Sep 2026 17:19:41 +0000 From: Pranjal Shrivastava To: David Matlack Cc: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Adithya Jayachandran , Alexander Graf , Alex Williamson , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Leon Romanovsky , Lukas Wunner , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pratyush Yadav , Randy Dunlap , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Vipin Sharma , William Tu , Yi Liu Subject: Re: [PATCH v9 09/13] PCI: liveupdate: Adopt ACS controls in incoming preserved devices Message-ID: References: <20260918200640.887030-1-dmatlack@google.com> <20260918200640.887030-10-dmatlack@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260918200640.887030-10-dmatlack@google.com> X-Stat-Signature: a3qrw9333iwbbewsyuyn1ubcsw8kodcz X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 4D7364000C X-HE-Tag: 1790615992-301340 X-HE-Meta: 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 aGdKA3fS P2u+kybdOYHi3NKds8rqPnQmdD6h6dGeh8lCUuObVIapeqz8Lr85epJsc6qXsGckElCfwBkJLAZxlWsodDcitZ0hpk7EWk/MIson6esPqEK/RPY0QqEMRSKEUcKlIh5HOoj0mqN7vXzBU1a3BEyB6fJEzD5ALaIQppiknmIrAwdb1xWPtuF0ab5X8sCBzPedcsLoBg9LvHFYOYWn568Ukoq8VM7iGY7Sc6SOh1Y47OvB5BGeF/u+WlOcMgZlaO1498SrOBDGwVyrcb76pG9xPlPO9/kGzR2MWCHCF1d47jeXb5J6Jp3tqJNzEKnq7VKyt+GcO/Ya0vGqq3Orle1AopZdjFwVIsUC0AdTi Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Sep 18, 2026 at 08:06:35PM +0000, David Matlack wrote: > Adopt Access Control Services (ACS) controls on all incoming preserved > devices (endpoints and upstream bridges) during a Live Update. > > Inheriting ACS flags avoids changing routing rules while memory > transactions are in flight from preserved devices. This is also strictly > necessary to ensure that IOMMU group assignments do not change during or > after Live Update. > > The adopted controls are recorded by the pci_save_state() call in > pci_bus_add_device(), which runs before drivers bind, so they are > automatically reapplied by pci_restore_state() if the device is reset. > If that save buffer could not be allocated there is nowhere to record > the adopted controls, and they would be silently lost by the first > reset. Program ACS from scratch in that case, which is a better outcome > than leaving ACS disabled. > > To simplify ACS inheritance, reject preserving any devices that require > quirks to enable ACS as those quirks would also have to take Live Update > into account. > > Signed-off-by: David Matlack Reviewed-by: Pranjal Shrivastava Thanks, Praan