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Wed, 25 Feb 2026 16:33:30 -0500 (EST) Date: Wed, 25 Feb 2026 14:33:28 -0700 From: Alex Williamson To: David Matlack Cc: 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?B?TWljaGHFgg==?= Winiarski" , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Raghavendra Rao Ananta , Rodrigo Vivi , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , "Thomas =?UTF-8?B?SGVsbHN0csO2bQ==?=" , Tomita Moeko , Vipin Sharma , Vivek Kasireddy , William Tu , Yi Liu , Zhu Yanjun , alex@shazbot.org Subject: Re: [PATCH v2 04/22] vfio/pci: Register a file handler with Live Update Orchestrator Message-ID: <20260225143328.35be89f6@shazbot.org> In-Reply-To: <20260129212510.967611-5-dmatlack@google.com> References: <20260129212510.967611-1-dmatlack@google.com> <20260129212510.967611-5-dmatlack@google.com> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: 5c18idkd1qsaqd8ahhexykgnn364xad5 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7DC6E100006 X-HE-Tag: 1772055215-696594 X-HE-Meta: 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 Xghg28WR gvF6sLPhYJURUbyowLamtLk7x5YmkYntPjDLnfA/12sV+vHnzfpfIZlydzvlfMXXusr0BRR37h1ysyK/wYFWyXO7uA7j89/pC9f/hn6GpmREeESwKM+fJn90FdZYPHb+9zyVJdgXIpCFvYPbxk8TXbBqBmJU2JVdpzKBfDS7+b9VZDVpmVanVyzK8uf1hqNOokL9jv6gIgLBzvmn1zCWlo/CiBI1qixneafFt+cLm4tOwMphagIwN09JqrmU8RniqnsKCsMk10tn2Sbb4YVoff2CbkPvZ9zhAtfgQo6qp1JIGQzI9vdY64VkkxwoHQnpl0/9W7+KLIn64E5N9iGTxKFLFn2lChyP9zpTg Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 29 Jan 2026 21:24:51 +0000 David Matlack wrote: > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c > index 0c771064c0b8..19e88322af2c 100644 > --- a/drivers/vfio/pci/vfio_pci.c > +++ b/drivers/vfio/pci/vfio_pci.c > @@ -258,6 +258,10 @@ static int __init vfio_pci_init(void) > int ret; > bool is_disable_vga = true; > > + ret = vfio_pci_liveupdate_init(); > + if (ret) > + return ret; > + > #ifdef CONFIG_VFIO_PCI_VGA > is_disable_vga = disable_vga; > #endif > @@ -266,8 +270,10 @@ static int __init vfio_pci_init(void) > > /* Register and scan for devices */ > ret = pci_register_driver(&vfio_pci_driver); > - if (ret) > + if (ret) { > + vfio_pci_liveupdate_cleanup(); > return ret; > + } > > vfio_pci_fill_ids(); > > @@ -281,6 +287,7 @@ module_init(vfio_pci_init); > static void __exit vfio_pci_cleanup(void) > { > pci_unregister_driver(&vfio_pci_driver); > + vfio_pci_liveupdate_cleanup(); > } > module_exit(vfio_pci_cleanup); > > diff --git a/drivers/vfio/pci/vfio_pci_liveupdate.c b/drivers/vfio/pci/vfio_pci_liveupdate.c > new file mode 100644 > index 000000000000..b84e63c0357b > --- /dev/null > +++ b/drivers/vfio/pci/vfio_pci_liveupdate.c > @@ -0,0 +1,69 @@ ... > +static const struct liveupdate_file_ops vfio_pci_liveupdate_file_ops = { > + .can_preserve = vfio_pci_liveupdate_can_preserve, > + .preserve = vfio_pci_liveupdate_preserve, > + .unpreserve = vfio_pci_liveupdate_unpreserve, > + .retrieve = vfio_pci_liveupdate_retrieve, > + .finish = vfio_pci_liveupdate_finish, > + .owner = THIS_MODULE, > +}; > + > +static struct liveupdate_file_handler vfio_pci_liveupdate_fh = { > + .ops = &vfio_pci_liveupdate_file_ops, > + .compatible = VFIO_PCI_LUO_FH_COMPATIBLE, > +}; > + > +int __init vfio_pci_liveupdate_init(void) > +{ > + if (!liveupdate_enabled()) > + return 0; > + > + return liveupdate_register_file_handler(&vfio_pci_liveupdate_fh); > +} liveupdate_register_file_handler() "pins" vfio-pci with a try_module_get(). Since this is done in our module_init function and unregister occurs in our module_exit function, rather than relative to any actual device binding or usage, this means vfio-pci CANNOT be unloaded. That seems bad. Thanks, Alex > + > +void vfio_pci_liveupdate_cleanup(void) > +{ > + if (!liveupdate_enabled()) > + return; > + > + liveupdate_unregister_file_handler(&vfio_pci_liveupdate_fh); > +}