[PATCH v13 06/10] iommu: Add a page fault handler

[Jean-Philippe Brucker]

On Wed, Mar 03, 2021 at 01:27:34PM +0800, Lu Baolu wrote:
> I have tested this framework with the Intel VT-d implementation. It
> works as expected. Hence,
> 
> Reviewed-by: Lu Baolu <baolu.lu at linux.intel.com>
> Tested-by: Lu Baolu <baolu.lu at linux.intel.com>

Thanks!

> One possible future optimization is that we could allow the system
> administrators to choose between handle PRQs in a workqueue or handle
> them synchronously. One research discovered that most of the software
> latency of handling a single page fault exists in the schedule part.
> Hence, synchronous processing will get shorter software latency if PRQs
> are rare and limited.

Yes, the risk is that processing a fault synchronously will take too much
time, leading to PRI queue overflow if the IOMMU keeps receiving page
faults. That's why I opted for the workqueue initially, but it's
definitely something we can tweak

Thanks,
Jean