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[34.142.210.164]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d676761c35sm18347475ad.15.2026.08.24.06.41.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Aug 2026 06:41:58 -0700 (PDT) Date: Mon, 24 Aug 2026 13:41:50 +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 , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Vipin Sharma , William Tu , Yi Liu Subject: Re: [PATCH v8 06/12] PCI: liveupdate: Auto-preserve upstream bridges across Live Update Message-ID: References: <20260728221007.2098560-1-dmatlack@google.com> <20260728221007.2098560-7-dmatlack@google.com> Precedence: bulk X-Mailing-List: linux-doc@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: <20260728221007.2098560-7-dmatlack@google.com> On Tue, Jul 28, 2026 at 10:10:00PM +0000, David Matlack wrote: > When a PCI device is preserved across a Live Update, all of its upstream > bridges up to the root port must also be preserved. This enables the PCI > core and any drivers bound to the bridges to manage bridges correctly > across a Live Update. > > Notably, this will be used in subsequent commits to ensure that > preserved devices can continue performing memory transactions without a > disruption or change in routing. > > To preserve bridges, the PCI core tracks the number of downstream > devices preserved under each bridge using a reference count in struct > pci_dev_ser. This allows a bridge to remain preserved until all its > downstream preserved devices are unpreserved or finish their > participation in the Live Update. > > Reviewed-by: Pasha Tatashin > Signed-off-by: David Matlack Reviewed-by: Pranjal Shrivastava Thanks, Praan