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(-)
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.
+#
# 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).
#
# @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.
+#
# 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"
" 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
--
2.48.1Vladimir 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
On 16.10.25 11:48, Markus Armbruster wrote:
> 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.
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
Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
> On 16.10.25 11:48, Markus Armbruster wrote:
>> 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>
[...]
>>> 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)
Just double-checking :)
The text you adjust is from 2010 (commit 82b0d80ef6a). I guess the
accelerator was experimental back then.
Mention the correction in the commit message?
[...]
On 16.10.25 13:38, Markus Armbruster wrote:
> Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
>
>> On 16.10.25 11:48, Markus Armbruster wrote:
>>> 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>
>
> [...]
>
>>>> 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)
>
> Just double-checking :)
>
> The text you adjust is from 2010 (commit 82b0d80ef6a). I guess the
> accelerator was experimental back then.
>
> Mention the correction in the commit message?
>
Will do
--
Best regards,
Vladimir
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