linux-kernel - Re: [PATCH 03/21] PCI: Require driver_override for incoming Live Update preserved devices

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Message-ID: <aS9XEm96ifPd_ier@google.com>
Date: Tue, 2 Dec 2025 21:16:02 +0000
From: David Matlack <dmatlack@...gle.com>
To: Alex Williamson <alex@...zbot.org>
Cc: Adithya Jayachandran <ajayachandra@...dia.com>,
	Alex Mastro <amastro@...com>, Alistair Popple <apopple@...dia.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Chris Li <chrisl@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Jacob Pan <jacob.pan@...ux.microsoft.com>,
	Jason Gunthorpe <jgg@...dia.com>, Jason Gunthorpe <jgg@...pe.ca>,
	Josh Hilke <jrhilke@...gle.com>, Kevin Tian <kevin.tian@...el.com>,
	kvm@...r.kernel.org, Leon Romanovsky <leonro@...dia.com>,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	linux-pci@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
	Mike Rapoport <rppt@...nel.org>, Parav Pandit <parav@...dia.com>,
	Pasha Tatashin <pasha.tatashin@...een.com>,
	Philipp Stanner <pstanner@...hat.com>,
	Pratyush Yadav <pratyush@...nel.org>,
	Saeed Mahameed <saeedm@...dia.com>,
	Samiullah Khawaja <skhawaja@...gle.com>,
	Shuah Khan <shuah@...nel.org>, Tomita Moeko <tomitamoeko@...il.com>,
	Vipin Sharma <vipinsh@...gle.com>, William Tu <witu@...dia.com>,
	Yi Liu <yi.l.liu@...el.com>, Yunxiang Li <Yunxiang.Li@....com>,
	Zhu Yanjun <yanjun.zhu@...ux.dev>
Subject: Re: [PATCH 03/21] PCI: Require driver_override for incoming Live
 Update preserved devices

On 2025-11-26 07:35 PM, David Matlack wrote:
> Require driver_override to be set to bind an incoming Live Update
> preserved device to a driver. Auto-probing could lead to the device
> being bound to a different driver than what was bound to the device
> prior to Live Update.
> 
> Delegate binding preserved devices to the right driver to userspace by
> requiring driver_override to be set on the device.
> 
> This restriction is relaxed once a driver calls
> pci_liveupdate_incoming_finish().
> 
> Signed-off-by: David Matlack <dmatlack@...gle.com>

After some offline discussion with Jason and Pasha, I will drop this
patch from the next version to avoid hard-coding a policy in the kernel.

Instead, for the time being, it will be the user's responsibility to
only preserve devices that do not have any built-in drivers that will
bind to the device during boot following a Live Update.