Re: [PATCH v9 00/20] Initial support for multi-process Qemu

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Aug 27, 2020 at 11:12:11AM -0700, elena.ufimtseva@oracle.com wrote:
> From: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> 
> Hello
> 
> This is the v9 of the patchset. Thank you very much for the
> detailed feedback for v8. We appreciate your time. We believe
> we have address all the comments for v8 in the current series.
> Special thanks to Stefan Hajnoczi.

I think overall it's in a good shape.
IIUC migration isn't supported yet so needs to be blocked.
But otherwise I don't see why we won't merge this and
interate on features upstream.

> The v9 has the following changes:
> - Communication channel. Qemu side uses blocking call to send
>   and receive the message from the remote and cannot progress
>   further until the remote side replies. Enhanced the
>   communication channel by dropping iothread lock before blocking
>   on Qemu end. Use the co-routines on the remote end to avoid
>   blocking QMP monitor;
> - removed the heartbeat functionality, it will be added later
>   in a full extent;
> - fixed leaked errors and similar fixes;
> - eliminated bytestream passing over the channel;
> - The build system had to be changed in order to accomodate the
>   latest changes in Qemu to use Kconfig/mason.
> 
> To touch upon the history of this project, we posted the
> Proof Of Concept patches before the BoF session in 2018.
> Subsequently, we posted 8 versions on the qemu-devel mailist.
> You can find them by following the links below ([1] - [8]).
> 
> Following people contributed to the design and
> implementation of this project:
> Jagannathan Raman <jag.raman@oracle.com>
> Elena Ufimtseva <elena.ufimtseva@oracle.com>
> John G Johnson <john.g.johnson@oracle.com>
> Stefan Hajnoczi <stefanha@redhat.com>
> Konrad Wilk <konrad.wilk@oracle.com>
> Kanth Ghatraju <kanth.ghatraju@oracle.com>
> 
> We would like to thank QEMU community for your feedback in the
> design and implementation of this project.
> 
> Qemu wiki page:
> https://wiki.qemu.org/Features/MultiProcessQEMU
> 
> For the full concept writeup about QEMU multi-process, please refer to
> docs/devel/qemu-multiprocess.rst. Also see docs/qemu-multiprocess.txt for
> usage information.
> 
> We welcome all your ideas, concerns, and questions for this patchset.
> 
> [POC]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg566538.html
> [1]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg602285.html
> [2]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg624877.html
> [3]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg642000.html
> [4]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg655118.html
> [5]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg682429.html
> [6]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg697484.html
> [7]: https://patchew.org/QEMU/cover.1593273671.git.elena.ufimtseva@oracle.com/
> [8]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg727007.html
> 
> Elena Ufimtseva (8):
>   multi-process: add qio channel function to transmit
>   multi-process: define MPQemuMsg format and transmission functions
>   multi-process: define transmission functions in remote
>   multi-process: introduce proxy object
>   multi-process: add proxy communication functions
>   multi-process: Forward PCI config space acceses to the remote process
>   multi-process: perform device reset in the remote process
>   multi-process: add configure and usage information
> 
> Jagannathan Raman (11):
>   memory: alloc RAM from file at offset
>   multi-process: Add config option for multi-process QEMU
>   multi-process: setup PCI host bridge for remote device
>   multi-process: setup a machine object for remote device process
>   multi-process: Initialize message handler in remote device
>   multi-process: Associate fd of a PCIDevice with its object
>   multi-process: setup memory manager for remote device
>   multi-process: PCI BAR read/write handling for proxy & remote
>     endpoints
>   multi-process: Synchronize remote memory
>   multi-process: create IOHUB object to handle irq
>   multi-process: Retrieve PCI info from remote process
> 
> John G Johnson (1):
>   multi-process: add the concept description to
>     docs/devel/qemu-multiprocess
> 
>  MAINTAINERS                     |  26 +
>  backends/hostmem-memfd.c        |   2 +-
>  configure                       |  10 +
>  docs/devel/index.rst            |   1 +
>  docs/devel/multi-process.rst    | 966 ++++++++++++++++++++++++++++++++
>  docs/multi-process.rst          |  67 +++
>  exec.c                          |  11 +-
>  hw/i386/meson.build             |   5 +
>  hw/i386/remote-iohub.c          | 123 ++++
>  hw/i386/remote-memory.c         |  58 ++
>  hw/i386/remote-msg.c            | 263 +++++++++
>  hw/i386/remote-obj.c            | 140 +++++
>  hw/i386/remote.c                |  79 +++
>  hw/misc/ivshmem.c               |   3 +-
>  hw/pci-host/meson.build         |   1 +
>  hw/pci-host/remote.c            |  75 +++
>  hw/pci/memory-sync.c            | 210 +++++++
>  hw/pci/meson.build              |   3 +
>  hw/pci/proxy.c                  | 363 ++++++++++++
>  include/exec/memory.h           |   2 +
>  include/exec/ram_addr.h         |   2 +-
>  include/hw/i386/remote-iohub.h  |  42 ++
>  include/hw/i386/remote-memory.h |  19 +
>  include/hw/i386/remote-obj.h    |  42 ++
>  include/hw/i386/remote.h        |  35 ++
>  include/hw/pci-host/remote.h    |  31 +
>  include/hw/pci/memory-sync.h    |  27 +
>  include/hw/pci/pci_ids.h        |   3 +
>  include/hw/pci/proxy.h          |  54 ++
>  include/io/channel.h            |  24 +
>  include/io/mpqemu-link.h        | 110 ++++
>  include/qemu/mmap-alloc.h       |   3 +-
>  io/channel.c                    |  45 ++
>  io/meson.build                  |   2 +
>  io/mpqemu-link.c                | 347 ++++++++++++
>  meson.build                     |   1 +
>  scripts/mpqemu-launcher.py      |  49 ++
>  softmmu/memory.c                |   3 +-
>  util/mmap-alloc.c               |   7 +-
>  util/oslib-posix.c              |   2 +-
>  40 files changed, 3243 insertions(+), 13 deletions(-)
>  create mode 100644 docs/devel/multi-process.rst
>  create mode 100644 docs/multi-process.rst
>  create mode 100644 hw/i386/remote-iohub.c
>  create mode 100644 hw/i386/remote-memory.c
>  create mode 100644 hw/i386/remote-msg.c
>  create mode 100644 hw/i386/remote-obj.c
>  create mode 100644 hw/i386/remote.c
>  create mode 100644 hw/pci-host/remote.c
>  create mode 100644 hw/pci/memory-sync.c
>  create mode 100644 hw/pci/proxy.c
>  create mode 100644 include/hw/i386/remote-iohub.h
>  create mode 100644 include/hw/i386/remote-memory.h
>  create mode 100644 include/hw/i386/remote-obj.h
>  create mode 100644 include/hw/i386/remote.h
>  create mode 100644 include/hw/pci-host/remote.h
>  create mode 100644 include/hw/pci/memory-sync.h
>  create mode 100644 include/hw/pci/proxy.h
>  create mode 100644 include/io/mpqemu-link.h
>  create mode 100644 io/mpqemu-link.c
>  create mode 100755 scripts/mpqemu-launcher.py
> 
> -- 
> 2.25.GIT