Re: [PATCH v2 2/3] PCI/PM: Do not save the config space of an inaccessible device

[sashiko-bot@kernel.org]

> pci_save_state() reads the standard header into dev->saved_config_space
> and marks it valid without checking that the device answered.  If the
> device is not accessible, every read returns all ones, the previous
> snapshot is overwritten, and pci_restore_state() writes the all-ones
> values back once the device answers again.  On a bridge that sets every
> writable bit of the Bridge Control register, Secondary Bus Reset
> included, and sets the primary, secondary and subordinate bus numbers
> to 0xff, which cuts off everything below it.
> 
> On a MacBookPro14,3 this happens to the upstream bridge of a
> Thunderbolt controller that drops off the bus while the system is
> suspending: after resume the bridge answers again, but with bus numbers
> ff/ff/ff and Secondary Bus Reset asserted, and the xHCI controllers
> behind it are removed.
> 
> [ ... ]
> If the device is not accessible, return -EIO and leave state_saved as it
> was.
> 
> Assisted-by: LLM
> Signed-off-by: Francisco Beltrán Millalén <fbeltranmillalen@gmail.com>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20260930141914.6678-1-fbeltranmillalen@gmail.com?part=2