Re: [PATCH v9 14/14] iommu: Track iopf group instead of last fault

[Baolu Lu]

On 1/6/24 1:53 AM, Jason Gunthorpe wrote:
> On Wed, Dec 20, 2023 at 09:23:32AM +0800, Lu Baolu wrote:
> >   /**
> > - * iommu_handle_iopf - IO Page Fault handler
> > - * @fault: fault event
> > - * @iopf_param: the fault parameter of the device.
> > + * iommu_report_device_fault() - Report fault event to device driver
> > + * @dev: the device
> > + * @evt: fault event data
> >    *
> > - * Add a fault to the device workqueue, to be handled by mm.
> > + * Called by IOMMU drivers when a fault is detected, typically in a threaded IRQ
> > + * handler. When this function fails and the fault is recoverable, it is the
> > + * caller's responsibility to complete the fault.
> This patch seems OK for what it does so:
>
> Reviewed-by: Jason Gunthorpe<jgg@xxxxxxxxxx>
>
> However, this seems like a strange design, surely this function should
> just call ops->page_response() when it can't enqueue the fault?
>
> It is much cleaner that way, so maybe you can take this into a
> following patch (along with the driver fixes to accomodate. (and
> perhaps iommu_report_device_fault() should return void too)
>
> Also iopf_group_response() should return void (another patch!),
> nothing can do anything with the failure. This implies that
> ops->page_response() must also return void - which is consistent with
> what the drivers do, the failure paths are all integrity validations
> of the fault and should be WARN_ON'd not return codes.

Make sense. I will integrate the code in the next version and convert
iommu_report_device_fault() to return void.

Best regards,
baolu