[PATCH v9 12/13] PCI: liveupdate: Do not disable bus mastering on preserved devices during kexec

[sashiko-bot at kernel.org]

> Do not disable bus mastering on outgoing preserved devices during
> pci_device_shutdown() for kexec.
> 
> Preserved devices must be allowed to perform memory transactions during
> a Live Update to ensure continuous operation.  Clearing the bus
> mastering bit would prevent these devices from issuing any memory
> requests while the new kernel boots.
> 
> Because bridges upstream of preserved endpoint devices are also
> automatically preserved, this change also avoids clearing bus mastering
> on them. This is critical because clearing bus mastering on an upstream
> bridge prevents the bridge from forwarding memory requests upstream (i.e.
> it would prevent the endpoint device from accessing system RAM and doing
> peer-to-peer transactions with devices not downstream of the bridge).
> 
> Reviewed-by: Pranjal Shrivastava <praan at google.com>
> Reviewed-by: Pasha Tatashin <pasha.tatashin at soleen.com>
> Reviewed-by: Samiullah Khawaja <skhawaja at google.com>
> Reviewed-by: Bjorn Helgaas <bhelgaas at google.com>
> Signed-off-by: David Matlack <dmatlack at google.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260918200640.887030-1-dmatlack@google.com?part=12