Re: [PATCH 3/7] iommu/vt-d: Use device_block_translation() in dev_attach error path

[Baolu Lu]

On 2022/11/5 10:09, Baolu Lu wrote:
> > btw this change is partial. @attach_dev still calls 
> > iommu_enable_pci_caps()
> > which always tries to enable PCI capabilities w/o checking whether they
> > have been enabled or not. Then user will hit -EBUSY when related PCI
> > helpers are called.
>
> Good catch!
>
> How about moving iommu_enable/disable_pci_caps() into
> iommu_probe/release_device() path? I may look into details if there's no
> significant arch gaps.

After reconsideration, it seems that this is not a feasible solution.
This changes the order in which PCI devices enable DMA.In addition, for
the kdump kernel, this is not feasible because there may be on-going DMA
on the device.

Perhaps I can make the iommu_enable_pci_caps() reentrant.

Best regards,
baolu