From: Marc-André Lureau <marcandre.lureau@redhat.com>

Hi,

This series adds support for running virtio GPUs in seperate
processes, thanks to vhost-user backend.

The QEMU support landed for 4.1. There are several benefits of running
the GPU/virgl in an external process, since Mesa is rather heavy on
the qemu main loop, and may block for a while, or crash.

The external GPU process is started with one end of a socket pair, the
other end is given to a QEMU chardev attached to a device. The
external process is also added to the cgroup to limit resources usage.

vhost-user is a generic mechanism that allows implementing virtio device
dataplane handling in a separate userspace process. vhost-user-gpu here
notably moves the virgl 3d handling out of the main qemu process. The
external process will be /usr/libexec/vhost-user-gpu, which comes from
qemu.git contrib/vhost-user-gpu code, first released in qemu-4.1.

Part of this series deals with discovering the location on disk of the
vhost-user-gpu binary, and what capabilities it provides. This uses a
similar mechanism to firmware.json, described in qemu
docs/interop/vhost-user.json

https://github.com/qemu/qemu/blob/master/docs/interop/vhost-user.json

qemu 4.1 ships a 50-qemu-gpu.json to match. I believe virtio-fs
will use a similar mechanism when it lands in upstream qemu, as
virtiofsd is a separate process that communicates with qemu over
vhost-user.

For a bit more background on vhost-user-gpu process handling and
the json interop motivation, here's some of the qemu discussion:

https://lists.nongnu.org/archive/html/qemu-devel/2018-08/msg02610.html
https://lists.nongnu.org/archive/html/qemu-devel/2018-09/msg00807.html

For this series, the XML to enable this is:

  <video model='virtio'>
    <driver name='vhostuser'/>
    <acceleration accel3d='yes' rendernode='/path/to/rendernode'/>
  </video>

rendernode is optional
qemu_vhost_user.c handles vhost-user.json
qemu_vhost_user_gpu.c handles the process management for
vhost-user-gpu

v3:
 - rename qemu_configs -> qemu_interop_config
 - replace <model .. vhostuser='yes'/> with <driver name='vhostuser'/>
 - move vhost_user_binary to virDomainVideoDriverDef
 - some VIR_AUTO usage improvements
 - introduce qemuDomainVideoPrivate to store vhost-user fd
 - improved selection of -device model
 - use DO_TEST_CAPS_LATEST
 - allocate a rendernode with virHostGetDRMRenderNode() - but no clear idea how to have a test
 - add a patch to ignore EPERM in virDirOpenIfExists()
 - better domain checks/validate
 - added Ján r-b
 - no s-o-b from Cole, per request and commits taken from his git branch
 - rebase, indentation/style fixes, update doc, version..

v2:
 - rebase to master
 - if test file build by dropping LDADDS usage
 - syntax-check issues:
     * use #pragma once
     * if () bracket issues
     * jump label indent issues
     * error message %s usage
     * size_t for loops

Marc-André Lureau (19):
  qemu: generalize qemuFetchConfigs
  util: ignore EACCESS in virDirOpenIfExists
  conf: format/parse/rng/docs for video <driver name='qemu|vhostuser'/>
  domain: add rendernode attribute on <accel>
  qemu-cgroup: allow accel rendernode access
  qemu: add vhost-user-gpu capabilities checks
  qemu: check that qemu is vhost-user-vga capable
  qemu: validate virtio-gpu with vhost-user
  qemu: restrict 'virgl=' option to non-vhostuser video type
  qemu: add vhost-user helpers
  qemu: add qemuSecurityStartVhostUserGPU helper
  conf: add privateData to virDomainVideoDef
  qemu: add qemuDomainVideoPrivate
  qemu: add vhost-user-gpu helper unit
  qemu: prepare domain for vhost-user GPU
  qemu: start/stop the vhost-user-gpu external device
  qemu: build vhost-user GPU devices
  tests: mock execv/execve
  tests: add vhost-user-gpu xml2argv tests

 docs/formatdomain.html.in                     |  18 +-
 docs/schemas/domaincommon.rng                 |  13 +
 src/conf/domain_conf.c                        |  87 +++-
 src/conf/domain_conf.h                        |  21 +-
 src/qemu/Makefile.inc.am                      |   6 +
 src/qemu/qemu_capabilities.c                  |   4 +
 src/qemu/qemu_capabilities.h                  |   2 +
 src/qemu/qemu_cgroup.c                        |  24 +
 src/qemu/qemu_command.c                       |  65 ++-
 src/qemu/qemu_domain.c                        |  50 ++-
 src/qemu/qemu_domain.h                        |  14 +-
 src/qemu/qemu_extdevice.c                     |  73 ++-
 src/qemu/qemu_extdevice.h                     |   5 +
 src/qemu/qemu_firmware.c                      | 144 +-----
 src/qemu/qemu_interop_config.c                | 183 ++++++++
 src/qemu/qemu_interop_config.h                |  25 ++
 src/qemu/qemu_process.c                       |  61 ++-
 src/qemu/qemu_security.c                      |  40 ++
 src/qemu/qemu_security.h                      |   6 +
 src/qemu/qemu_vhost_user.c                    | 422 ++++++++++++++++++
 src/qemu/qemu_vhost_user.h                    |  48 ++
 src/qemu/qemu_vhost_user_gpu.c                | 285 ++++++++++++
 src/qemu/qemu_vhost_user_gpu.h                |  50 +++
 src/util/virfile.c                            |  13 +-
 tests/Makefile.am                             |   9 +
 .../caps_4.1.0.x86_64.xml                     |   2 +
 .../etc/qemu/vhost-user/40-gpu.json           |   1 +
 .../etc/qemu/vhost-user/50-gpu.json           |   0
 .../qemu/vhost-user/test-vhost-user-gpu       |  11 +
 .../usr/share/qemu/vhost-user/30-gpu.json     |   1 +
 .../usr/share/qemu/vhost-user/50-gpu.json     |   8 +
 .../usr/share/qemu/vhost-user/60-gpu.json     |   1 +
 tests/qemuvhostusertest.c                     | 132 ++++++
 ...host-user-gpu-secondary.x86_64-latest.args |  43 ++
 .../vhost-user-gpu-secondary.xml              |  46 ++
 .../vhost-user-vga.x86_64-latest.args         |  40 ++
 tests/qemuxml2argvdata/vhost-user-vga.xml     |  42 ++
 tests/qemuxml2argvdata/virtio-options.args    |   5 +-
 tests/qemuxml2argvdata/virtio-options.xml     |   4 +-
 tests/qemuxml2argvtest.c                      |  15 +-
 tests/virfilewrapper.c                        |  22 +
 41 files changed, 1832 insertions(+), 209 deletions(-)
 create mode 100644 src/qemu/qemu_interop_config.c
 create mode 100644 src/qemu/qemu_interop_config.h
 create mode 100644 src/qemu/qemu_vhost_user.c
 create mode 100644 src/qemu/qemu_vhost_user.h
 create mode 100644 src/qemu/qemu_vhost_user_gpu.c
 create mode 100644 src/qemu/qemu_vhost_user_gpu.h
 create mode 120000 tests/qemuvhostuserdata/etc/qemu/vhost-user/40-gpu.json
 create mode 100644 tests/qemuvhostuserdata/etc/qemu/vhost-user/50-gpu.json
 create mode 100755 tests/qemuvhostuserdata/usr/libexec/qemu/vhost-user/test-vhost-user-gpu
 create mode 120000 tests/qemuvhostuserdata/usr/share/qemu/vhost-user/30-gpu.json
 create mode 100644 tests/qemuvhostuserdata/usr/share/qemu/vhost-user/50-gpu.json
 create mode 120000 tests/qemuvhostuserdata/usr/share/qemu/vhost-user/60-gpu.json
 create mode 100644 tests/qemuvhostusertest.c
 create mode 100644 tests/qemuxml2argvdata/vhost-user-gpu-secondary.x86_64-latest.args
 create mode 100644 tests/qemuxml2argvdata/vhost-user-gpu-secondary.xml
 create mode 100644 tests/qemuxml2argvdata/vhost-user-vga.x86_64-latest.args
 create mode 100644 tests/qemuxml2argvdata/vhost-user-vga.xml

-- 
2.23.0

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