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Mon, 02 Feb 2026 10:15:24 -0800 (PST) MIME-Version: 1.0 References: <20260129212510.967611-1-dmatlack@google.com> <20260129212510.967611-3-dmatlack@google.com> <44484594-5b5d-4237-993c-ac1e173ad62e@linux.dev> In-Reply-To: <44484594-5b5d-4237-993c-ac1e173ad62e@linux.dev> From: David Matlack Date: Mon, 2 Feb 2026 10:14:56 -0800 X-Gm-Features: AZwV_QhgTJZ7rnxODmCU1qhjsI1pWSHh1k-rPTozueyr5OUveeJ2FC59ISanCNo Message-ID: Subject: Re: [PATCH v2 02/22] PCI: Add API to track PCI devices preserved across Live Update To: Zhu Yanjun Cc: Alex Williamson , Adithya Jayachandran , Alexander Graf , Alex Mastro , Alistair Popple , Andrew Morton , Ankit Agrawal , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Jason Gunthorpe , Jonathan Corbet , Josh Hilke , Kevin Tian , kexec@lists.infradead.org, kvm@vger.kernel.org, Leon Romanovsky , Leon Romanovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Lukas Wunner , =?UTF-8?Q?Micha=C5=82_Winiarski?= , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Stat-Signature: 1dnna9mwghpg1ds1ujrjpjitfsxxtzoy X-Rspam-User: X-Rspamd-Queue-Id: D159F10000C X-HE-Tag: 1770056126-363112 X-HE-Meta: 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 3I4rYElR Lfl7dZHU4yzZFji8jPwWoqQflM85TCcyREwjYW55WxoR+dM5lnLZGDijP8+Qx5dfV5nqRjj2aMNeKtWZ85GIkuRHBjTcTY29vNT8+CqWUsQHpBfxGLVfZ8aeQ3tzQVZbMf9E6s6Nm/X40ne6gKe0UESboZGkPWZ3Cie9qwwG9l7JTssovlTOKMGncs5J0EwmT7nEkPsvmK+2HsawXBKw+511c6u3lpcoeoo/0iDwXKUoTQr8= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Jan 31, 2026 at 10:38=E2=80=AFPM Zhu Yanjun = wrote: > > =E5=9C=A8 2026/1/29 13:24, David Matlack =E5=86=99=E9=81=93: > > Add an API to enable the PCI subsystem to track all devices that are > > preserved across a Live Update, including both incoming devices (passed > > from the previous kernel) and outgoing devices (passed to the next > > kernel). > > > > Use PCI segment number and BDF to keep track of devices across Live > > Update. This means the kernel must keep both identifiers constant acros= s > > a Live Update for any preserved device. VFs are not supported for now, > > since that requires preserving SR-IOV state on the device to ensure the > > same number of VFs appear after kexec and with the same BDFs. > > > > Drivers that preserve devices across Live Update can now register their > > struct liveupdate_file_handler with the PCI subsystem so that the PCI > > subsystem can allocate and manage File-Lifecycle-Bound (FLB) global dat= a > > to track the list of incoming and outgoing preserved devices. > > > > pci_liveupdate_register_fh(driver_fh) > > pci_liveupdate_unregister_fh(driver_fh) > > Can the above 2 functions support the virtual devices? For example, > bonding, veth, iSWAP and RXE. > > These virtual devices do not have BDF. As such, I am not sure if your > patches take these virtual devices in to account. No this patch series only supports PCI devices, since those are the only devices so far we've needed to support. I am not familiar with any of the devices that you mentioned. If they are virtual then does that mean it's all just software? In that case I would be curious to know what problem is solved by preserving them in the kernel, vs. tearing them down and rebuilding them across a Live Udpate.