Re: [PATCH v9 3/9] PCI: Avoid saving config space state in reset path

[Farhan Ali <alifm@linux.ibm.com>]

On 2/17/2026 11:11 AM, Keith Busch wrote:
> On Tue, Feb 17, 2026 at 10:22:51AM -0800, Farhan Ali wrote:
>> The current reset process saves the device's config space state before
>> reset and restores it afterward. However errors may occur unexpectedly and
>> it may then be impossible to save config space because the device may be
>> inaccessible (e.g. DPC) or config space may be corrupted. This results in
>> saving corrupted values that get written back to the device during state
>> restoration.
>>
>> Since commit a2f1e22390ac ("PCI/ERR: Ensure error recoverability at all times"),
>> we now save the state of device at enumeration. On every restore we should
>> either use the enumeration saved state or driver's intentional saved state,
>> never a state saved at the unpredictable time of an error recovery reset.
> The vfio driver calls pci_try_reset_function after pci_enable_device,
> but before calling pci_store_saved_state. Won't this change, then, mean
> that the PCI Command register will get restored to the wrong state with
> the resources disabled?

Yes I think you are right, with this change the PCI Command register 
gets restored to state at enumeration. So we will lose the updated state 
after pci_clear_master() and pci_enable_device(). I think we can update 
the vfio driver to call pci_save_state() after pci_enable_device()?

Thanks

Farhan