hns: Add support for Dynamic Context Attachment

[Wenpeng-Liang]

The HIP09 introduces the DCA(Dynamic Context Attachment) feature which supports many RC QPs to share the WQE buffer in a memory pool. If a QP enables DCA feature, the WQE's buffer will not be allocated when creating but when the users start to post WRs. This will reduce the memory consumption when there are too many QPs are inactive.

For more detailed information, please refer to the man pages provided by the last patch of this series.

This series is associated with the kernel one "RDMA/hns: Add support for Dynamic Context Attachment", and two RFC versions of this series has been sent before.

Changes since v1:

• Add DCA pyverbs test cases.
• Add a shared memory mechanism to synchronize status of DCA.
• Link: https://patchwork.kernel.org/project/linux-rdma/cover/[email protected]/

No changes since RFC v2.

• Link: https://patchwork.kernel.org/project/linux-rdma/cover/[email protected]/

Changes since RFC v1:

• Add direct verbs to set the parameters about size that used to configuring DCA.
• Add man pages to explain what is DCA, how does it works and how to use it.
• Link: https://patchwork.kernel.org/project/linux-rdma/cover/[email protected]/

[jgunthorpe]

Please fix the build failures.

[jgunthorpe]

@EdwardSro should look at the pyverbs changes

[jgunthorpe]

I don't see the kernel side of this on the kernel patchworks any more, should we close this PR?