Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
This option for tap and vhost-user netdevs doesn't make sense since long ago (10 years!), starting from commits:
1e7398a140f7a6 ("vhost: enable vhost without without MSI-X") 24f938a682d934 ("vhost user:support vhost user nic for non msi guests")
Prior these commits, to enable kernel vhost-net, or vhost-user-net for some specific kind of guests (that don't have MSI-X support), you should have set vhostforce=on.
Now guest type doesn't matter, all guests are equal for these options logic.
For tap the current logic is: vhost=on / vhost=off : vhostforce ignored, doesn't make sense vhost unset : vhostforce counts, enabling vhost
So you may enable vhost for tap several ways: - vhost=on - vhostforce=on - vhost=on + vhostforce=on - and even vhost=on + vhostforce=off
- they are all equal.
For vhost-user we simply ignore the vhostforce option at all in the code.
Let's finally deprecate the extra options.
Also, fix @vhostforce documentation everywhere to show the real picture, and update vhost-user test to not use deprecated option.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> ---
v4: - update documentation - deprecate also similar option for vhost-user net
v3 was "[PATCH v3] qapi: net/tap: deprecate vhostforce option": Supersedes: <20250901153943.65235-1-vsementsov@yandex-team.ru>
docs/about/deprecated.rst | 11 +++++++++++ qapi/net.json | 20 ++++++++++++++++---- qemu-options.hx | 13 +++++-------- tests/qtest/vhost-user-test.c | 2 +- 4 files changed, 33 insertions(+), 13 deletions(-)
diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index 98361f5832..2882603b20 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -487,6 +487,17 @@ Stream ``reconnect`` (since 9.2) The ``reconnect`` option only allows specifying second granularity timeouts, which is not enough for all types of use cases, use ``reconnect-ms`` instead.
+TAP ``vhostforce`` (since 10.2) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The ``vhostforce`` option is redundant with the ``vhost`` option. +If they conflict, ``vhost`` takes precedence. Just use ``vhost``. + +Vhost-user ``vhostforce`` (since 10.2) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The ``vhostforce`` option is a no-op. Do not use it. + CPU device properties '''''''''''''''''''''
diff --git a/qapi/net.json b/qapi/net.json index 60d196afe5..531b360e46 100644 --- a/qapi/net.json +++ b/qapi/net.json @@ -346,13 +346,20 @@ # @vhostfds: file descriptors of multiple already opened vhost net # devices # -# @vhostforce: vhost on for non-MSIX virtio guests +# @vhostforce: enable vhost-net network accelerator. Ignored when +# @vhost is set. # # @queues: number of queues to be created for multiqueue capable tap # # @poll-us: maximum number of microseconds that could be spent on busy # polling for tap (since 2.7) # +# Features: +# +# @deprecated: Member @vhostforce is deprecated. The @vhostforce +# option is redundant with the @vhost option. If they conflict, +# @vhost takes precedence. Just use @vhost.
Behavior should be discussed in the descriptions instead. I think what we already have there ("Ignored when @vhost is set") suffices. Let's use the common phrasing here: # @deprecated: Member @vhostforce is deprecated. Use @vhost instead.
+# # Since: 1.2 ## { 'struct': 'NetdevTapOptions', @@ -369,7 +376,7 @@ '*vhost': 'bool', '*vhostfd': 'str', '*vhostfds': 'str', - '*vhostforce': 'bool', + '*vhostforce': { 'type': 'bool', 'features': [ 'deprecated' ] }, '*queues': 'uint32', '*poll-us': 'uint32'} }
@@ -606,17 +613,22 @@ # # @chardev: name of a unix socket chardev # -# @vhostforce: vhost on for non-MSIX virtio guests (default: false). +# @vhostforce: no-op (default: false).
Suggest # @vhostforce: silently ignored, exists just for backward # compatibility.
# # @queues: number of queues to be created for multiqueue vhost-user # (default: 1) (Since 2.5) # +# Features: +# +# @deprecated: Member @vhostforce is deprecated. The @vhostforce +# option is ignored in code and does nothing. Don't use it.
Again, discussion of behavior does not belong here. I think # @deprecated: Member @vhostforce is deprecated. suffices.
+# # Since: 2.1 ## { 'struct': 'NetdevVhostUserOptions', 'data': { 'chardev': 'str', - '*vhostforce': 'bool', + '*vhostforce': { 'type': 'bool', 'features': [ 'deprecated' ] }, '*queues': 'int' } }
## diff --git a/qemu-options.hx b/qemu-options.hx index 0223ceffeb..35a70096e8 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -2882,7 +2882,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, #else "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n" " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" - " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" + " [,vhostfd=h][,vhostfds=x:y:...:z][,queues=n]\n" " [,poll-us=n]\n" " configure a host TAP network backend with ID 'str'\n" " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" @@ -2898,9 +2898,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n" " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" - " use vhost=on to enable experimental in kernel accelerator\n" - " (only has effect for virtio guests which use MSIX)\n" - " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" + " use vhost=on to enable in kernel accelerator\n"
So the kernel's accelerator is no longer experimental?
" use 'vhostfd=h' to connect to an already opened vhost net device\n" " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n" " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n" @@ -2991,7 +2989,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, " use 'start-queue=m' to specify the first queue that should be used\n" #endif #ifdef CONFIG_POSIX - "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" + "-netdev vhost-user,id=str,chardev=dev\n" " configure a vhost-user network, backed by a chardev 'dev'\n" #endif #ifdef __linux__ @@ -3882,12 +3880,11 @@ SRST for insertion into the socket map. The combination of 'map-path' and 'sock-fds' together is not supported.
-``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]`` +``-netdev vhost-user,chardev=id[,queues=n]`` Establish a vhost-user netdev, backed by a chardev id. The chardev should be a unix domain socket backed one. The vhost-user uses a specifically defined protocol to pass vhost ioctl replacement - messages to an application on the other end of the socket. On - non-MSIX guests, the feature can be forced with vhostforce. Use + messages to an application on the other end of the socket. Use 'queues=n' to specify the number of queues to be created for multiqueue vhost-user.
diff --git a/tests/qtest/vhost-user-test.c b/tests/qtest/vhost-user-test.c index 609ff24059..a4862d7087 100644 --- a/tests/qtest/vhost-user-test.c +++ b/tests/qtest/vhost-user-test.c @@ -46,7 +46,7 @@ #define QEMU_CMD_SHM " -m %d -object memory-backend-shm,id=mem,size=%dM," \ " -numa node,memdev=mem" #define QEMU_CMD_CHR " -chardev socket,id=%s,path=%s%s" -#define QEMU_CMD_NETDEV " -netdev vhost-user,id=hs0,chardev=%s,vhostforce=on" +#define QEMU_CMD_NETDEV " -netdev vhost-user,id=hs0,chardev=%s"
#define HUGETLBFS_MAGIC 0x958458f6