Unclear qemu version recommendation

[FlorianFreudiger]

It is unclear what qemu version/branch one should use with the latest libvfio-user, quickly looking through the repo I found 3 references to different qemu trees.

• The Readme references branch vfio-user-6.2
  

  libvfio-user/README.md

  Line 248 in 8872c36

  build [this branch of qemu](https://github.com/oracle/qemu/tree/vfio-user-6.2).

• spdk.md seems to references this tree: https://github.com/oracle/qemu/tree/d377d483f962d6ff7e9ca5c01091687e3f3797a7
  

  libvfio-user/docs/spdk.md

  Line 12 in 8872c36

  Use Oracle's QEMU d377d483f9 from https://github.com/oracle/qemu:

• In recent issue nvmf_vfio_user_prop_req_rsp: failed to map Admin queue #757 the above sha was used and in response branch vfio-user-p3.0 was mentioned

  Can you try using https://github.com/oracle/qemu/tree/vfio-user-p3.0 Qemu and latest spdk

  Originally posted by @swapnili in nvmf_vfio_user_prop_req_rsp: failed to map Admin queue #757 (comment)

Given that 2 of these 3 had their last commit more than 1 year ago I'm guessing some of them are outdated?

It would be nice if some clarification would be provided on

• if these qemu branches/trees are still recommended to use with the latest libvfio-user
• which branches are still maintained
• and if necessary which ones are to be used with specific projects (e.g. spdk)

[tmakatos]

@jraman567 just double checking, according to https://libvfio-user.slack.com/archives/C01AFGCSPTR/p1691524931726739?thread_ts=1691407356.878539&cid=C01AFGCSPTR we should be using https://github.com/oracle/qemu/tree/vfio-user-p3.1?