On 16.10.25 11:48, Markus Armbruster wrote:
Vladimir Sementsov-Ogievskiy <[email protected]> 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 <[email protected]>
---
v4:
- update documentation
- deprecate also similar option for vhost-user net
v3 was "[PATCH v3] qapi: net/tap: deprecate vhostforce option":
Supersedes: <[email protected]>
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.
OK
+#
# 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.
Sounds good, OK
#
# @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?
Reading this, I heard the first time that vhost-net is experimental.
It's about 15 years old, and used in production. I think "experimental"
is inappropriate word here)
" 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
--
Best regards,
Vladimir
