Re: [PATCH v3 0/4] iommu/vt-d: Add page request draining support

From: Lu Baolu
Date: Mon Apr 27 2020 - 21:47:13 EST


Hi Kevin,

On 2020/4/22 16:06, Lu Baolu wrote:
When a PASID is stopped or terminated, there can be pending PRQs
(requests that haven't received responses) in the software and
remapping hardware. The pending page requests must be drained
so that the pasid could be reused. The chapter 7.10 in the VT-d
specification specifies the software steps to drain pending page
requests and responses.

This includes two parts:
- PATCH 1/4 ~ 2/4: refactor the qi_submit_sync() to support multiple
descriptors per submission which will be used in the following
patch.
- PATCH 3/4 ~ 4/4: add page request drain support after a pasid entry
is torn down.

Please help to review.

Best regards,
baolu

Change log:
v2->v3:
- Address Kevin's review comments
- Squash the first 2 patches together;
- The prq thread is serialized, no need to consider reentrance;
- Ensure no new-coming prq before drain prq in queue;
- Handle page request overflow case.

Very appreciated for your review comments.

How about these changes? Any comments?

Best regards,
baolu