Re: [PATCH v3 00/11] iommu: Prepare to deliver page faults to user space

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On 2023/8/22 2:31, Jason Gunthorpe wrote:
On Fri, Aug 18, 2023 at 07:40:36AM +0800, Lu Baolu wrote:
When a user-managed page table is attached to an IOMMU, it is necessary
to deliver IO page faults to user space so that they can be handled
appropriately. One use case for this is nested translation, which is
currently being discussed in the mailing list.

I have posted a RFC series [1] that describes the implementation of
delivering page faults to user space through IOMMUFD. This series has
received several comments on the IOMMU refactoring, which I am trying to
address in this series.

Looking at this after all the patches are applied..

Thank you very much for reviewing my patches.


iommu_report_device_fault() and iommu_queue_iopf() should be put in
the same file.

Yes. I will move both into io-pgfault.c. After that, iommu_queue_iopf()
becomes static.


iommu_queue_iopf() seems misnamed since it isn't queuing anything. It
is delivering the fault to the domain.

Yeah, perhaps we can rename it to iommu_handle_iopf().

/**
 * iommu_handle_iopf - IO Page Fault handler
 * @fault: fault event
 * @dev: struct device.


It is weird that iommu_sva_domain_alloc is not in the sva file

Agreed. I will move it to iommu-sva.c.

iopf_queue_work() wrappers a work queue, but it should trampoline
through another function before invoking the driver's callback and not
invoke it with a weird work_struct - decode the group and get back the
domain. Every single handler will require the group and domain.

The work queue wrapper is duplicate. I will remove it and let the driver
to call queue_work() directly.


Same for domain->iopf_handler, the domain should be an argument if we
are invoking the function on a domain.

Perhaps group->domain is a simple answer.

Yes. I will add domain in fault group and make it part of the parameters
of the callback.

Best regards,
baolu



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