This field is mostly unused and sometimes confusing (we even have
a TODO-like comment to drop it). Let's finally do.
The field is used to held VHOST_USER_F_PROTOCOL_FEATURES for vhost-user
and/or VHOST_NET_F_VIRTIO_NET_HDR for vhost-net (which may be
vhost-user-net). But we can simply recalculate these two flags in place
from hdev->features, and from net-client for VHOST_NET_F_VIRTIO_NET_HDR.
Note: removing field from x-query-virtio-status result is incompatible
change. We can do it because the command is unstable.
Cc: qemu-stable@nongnu.org
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
hw/block/vhost-user-blk.c | 1 -
hw/net/vhost_net.c | 26 ++++++++++++++------------
hw/scsi/vhost-scsi.c | 1 -
hw/scsi/vhost-user-scsi.c | 1 -
hw/virtio/vdpa-dev.c | 1 -
hw/virtio/vhost-user.c | 17 ++++++++---------
hw/virtio/virtio-hmp-cmds.c | 2 --
hw/virtio/virtio-qmp.c | 4 ----
include/hw/virtio/vhost.h | 7 -------
qapi/virtio.json | 3 ---
10 files changed, 22 insertions(+), 41 deletions(-)
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index c0cc5f6942..de7a810c93 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -348,7 +348,6 @@ static int vhost_user_blk_connect(DeviceState *dev, Error **errp)
s->dev.nvqs = s->num_queues;
s->dev.vqs = s->vhost_vqs;
s->dev.vq_index = 0;
- s->dev.backend_features = 0;
vhost_dev_set_config_notifier(&s->dev, &blk_ops);
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 25e9f1fd24..fda90e231e 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -52,8 +52,14 @@ int vhost_net_set_config(struct vhost_net *net, const uint8_t *data,
void vhost_net_ack_features_ex(struct vhost_net *net, const uint64_t *features)
{
- virtio_features_copy(net->dev.acked_features_ex,
- net->dev.backend_features_ex);
+ virtio_features_clear(net->dev.acked_features_ex);
+ if (net->backend == -1) {
+ net->dev.acked_features =
+ net->dev.features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
+ } else if (!qemu_has_vnet_hdr(net->nc)) {
+ net->dev.acked_features = 1ULL << VHOST_NET_F_VIRTIO_NET_HDR;
+ }
+
vhost_ack_features_ex(&net->dev, net->feature_bits, features);
}
@@ -258,12 +264,9 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
if (r < 0) {
goto fail;
}
- net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend)
- ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR);
net->backend = r;
net->dev.protocol_features = 0;
} else {
- virtio_features_clear(net->dev.backend_features_ex);
net->dev.protocol_features = 0;
net->backend = -1;
@@ -284,13 +287,12 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
net->dev.features &= ~(1ULL << VIRTIO_NET_F_MRG_RXBUF);
}
- if (virtio_features_andnot(missing_features,
- net->dev.backend_features_ex,
- net->dev.features_ex)) {
- fprintf(stderr, "vhost lacks feature mask 0x" VIRTIO_FEATURES_FMT
- " for backend\n", VIRTIO_FEATURES_PR(missing_features));
- goto fail;
- }
+ if (!qemu_has_vnet_hdr(options->net_backend) &&
+ (~net->dev.features & (1ULL << VHOST_NET_F_VIRTIO_NET_HDR))) {
+ fprintf(stderr, "vhost lacks feature mask 0x%llx for backend\n",
+ ~net->dev.features & (1ULL << VHOST_NET_F_VIRTIO_NET_HDR));
+ goto fail;
+ }
}
/* Set sane init value. Override when guest acks. */
diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index cdf405b0f8..d694a25fe2 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -276,7 +276,6 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
vqs = g_new0(struct vhost_virtqueue, vsc->dev.nvqs);
vsc->dev.vqs = vqs;
vsc->dev.vq_index = 0;
- vsc->dev.backend_features = 0;
ret = vhost_dev_init(&vsc->dev, (void *)(uintptr_t)vhostfd,
VHOST_BACKEND_TYPE_KERNEL, 0, errp);
diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
index 25f2d894e7..0c80a271d8 100644
--- a/hw/scsi/vhost-user-scsi.c
+++ b/hw/scsi/vhost-user-scsi.c
@@ -159,7 +159,6 @@ static int vhost_user_scsi_connect(DeviceState *dev, Error **errp)
vsc->dev.nvqs = VIRTIO_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
vsc->dev.vqs = s->vhost_vqs;
vsc->dev.vq_index = 0;
- vsc->dev.backend_features = 0;
ret = vhost_dev_init(&vsc->dev, &s->vhost_user, VHOST_BACKEND_TYPE_USER, 0,
errp);
diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
index 4a7b970976..efd9f68420 100644
--- a/hw/virtio/vdpa-dev.c
+++ b/hw/virtio/vdpa-dev.c
@@ -104,7 +104,6 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
v->dev.vqs = vqs;
v->dev.vq_index = 0;
v->dev.vq_index_end = v->dev.nvqs;
- v->dev.backend_features = 0;
v->started = false;
ret = vhost_vdpa_get_iova_range(v->vhostfd, &iova_range);
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index f367ce06ce..b80174f489 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1448,14 +1448,15 @@ static int vhost_user_set_features(struct vhost_dev *dev,
int ret;
/*
- * We need to include any extra backend only feature bits that
- * might be needed by our device. Currently this includes the
- * VHOST_USER_F_PROTOCOL_FEATURES bit for enabling protocol
- * features.
+ * Don't lose VHOST_USER_F_PROTOCOL_FEATURES, which is vhost-user
+ * specific.
*/
- ret = vhost_user_set_u64(dev, VHOST_USER_SET_FEATURES,
- features | dev->backend_features,
- log_enabled);
+ if (virtio_has_feature(dev->features, VHOST_USER_F_PROTOCOL_FEATURES)) {
+ features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
+ }
+
+ ret = vhost_user_set_u64(dev, VHOST_USER_SET_FEATURES, features,
+ log_enabled);
if (virtio_has_feature(dev->protocol_features,
VHOST_USER_PROTOCOL_F_STATUS)) {
@@ -2189,8 +2190,6 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque,
(dev->config_ops && dev->config_ops->vhost_dev_config_notifier);
uint64_t protocol_features;
- dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
-
err = vhost_user_get_u64(dev, VHOST_USER_GET_PROTOCOL_FEATURES,
&protocol_features);
if (err < 0) {
diff --git a/hw/virtio/virtio-hmp-cmds.c b/hw/virtio/virtio-hmp-cmds.c
index 1daae482d3..4bf9a3109d 100644
--- a/hw/virtio/virtio-hmp-cmds.c
+++ b/hw/virtio/virtio-hmp-cmds.c
@@ -176,8 +176,6 @@ void hmp_virtio_status(Monitor *mon, const QDict *qdict)
hmp_virtio_dump_features(mon, s->vhost_dev->features);
monitor_printf(mon, " Acked features:\n");
hmp_virtio_dump_features(mon, s->vhost_dev->acked_features);
- monitor_printf(mon, " Backend features:\n");
- hmp_virtio_dump_features(mon, s->vhost_dev->backend_features);
monitor_printf(mon, " Protocol features:\n");
hmp_virtio_dump_protocols(mon, s->vhost_dev->protocol_features);
}
diff --git a/hw/virtio/virtio-qmp.c b/hw/virtio/virtio-qmp.c
index b338344c6c..dd1a38e792 100644
--- a/hw/virtio/virtio-qmp.c
+++ b/hw/virtio/virtio-qmp.c
@@ -780,8 +780,6 @@ VirtioStatus *qmp_x_query_virtio_status(const char *path, Error **errp)
vdev->guest_features_ex);
status->host_features = qmp_decode_features(vdev->device_id,
vdev->host_features_ex);
- status->backend_features = qmp_decode_features(vdev->device_id,
- vdev->backend_features_ex);
switch (vdev->device_endian) {
case VIRTIO_DEVICE_ENDIAN_LITTLE:
@@ -822,8 +820,6 @@ VirtioStatus *qmp_x_query_virtio_status(const char *path, Error **errp)
qmp_decode_features(vdev->device_id, hdev->features_ex);
status->vhost_dev->acked_features =
qmp_decode_features(vdev->device_id, hdev->acked_features_ex);
- status->vhost_dev->backend_features =
- qmp_decode_features(vdev->device_id, hdev->backend_features_ex);
status->vhost_dev->protocol_features =
qmp_decode_protocols(hdev->protocol_features);
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 1ee639dd7e..3e69e47833 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -100,16 +100,9 @@ struct vhost_dev {
*
* @features: available features provided by the backend
* @acked_features: final negotiated features with front-end driver
- *
- * @backend_features: this is used in a couple of places to either
- * store VHOST_USER_F_PROTOCOL_FEATURES to apply to
- * VHOST_USER_SET_FEATURES or VHOST_NET_F_VIRTIO_NET_HDR. Its
- * future use should be discouraged and the variable retired as
- * its easy to confuse with the VirtIO backend_features.
*/
VIRTIO_DECLARE_FEATURES(features);
VIRTIO_DECLARE_FEATURES(acked_features);
- VIRTIO_DECLARE_FEATURES(backend_features);
/**
* @protocol_features: is the vhost-user only feature set by
diff --git a/qapi/virtio.json b/qapi/virtio.json
index 05295ab665..b995a5bb6d 100644
--- a/qapi/virtio.json
+++ b/qapi/virtio.json
@@ -85,8 +85,6 @@
#
# @acked-features: vhost_dev acked_features
#
-# @backend-features: vhost_dev backend_features
-#
# @protocol-features: vhost_dev protocol_features
#
# @max-queues: vhost_dev max_queues
@@ -106,7 +104,6 @@
'vq-index': 'int',
'features': 'VirtioDeviceFeatures',
'acked-features': 'VirtioDeviceFeatures',
- 'backend-features': 'VirtioDeviceFeatures',
'protocol-features': 'VhostDeviceProtocols',
'max-queues': 'uint64',
'backend-cap': 'uint64',
--
2.48.1On 10/12/25 02:23, Vladimir Sementsov-Ogievskiy wrote: > This field is mostly unused and sometimes confusing (we even have > a TODO-like comment to drop it). Let's finally do. > > The field is used to held VHOST_USER_F_PROTOCOL_FEATURES for vhost-user > and/or VHOST_NET_F_VIRTIO_NET_HDR for vhost-net (which may be > vhost-user-net). But we can simply recalculate these two flags in place > from hdev->features, and from net-client for VHOST_NET_F_VIRTIO_NET_HDR. > > Note: removing field from x-query-virtio-status result is incompatible > change. We can do it because the command is unstable. > > Cc: qemu-stable@nongnu.org Why do you think this change deserves qemu-stable? Does it fix a bug or is it just a clean-up? Thanks, /mjt
On 14.10.25 18:28, Michael Tokarev wrote: > On 10/12/25 02:23, Vladimir Sementsov-Ogievskiy wrote: >> This field is mostly unused and sometimes confusing (we even have >> a TODO-like comment to drop it). Let's finally do. >> >> The field is used to held VHOST_USER_F_PROTOCOL_FEATURES for vhost-user >> and/or VHOST_NET_F_VIRTIO_NET_HDR for vhost-net (which may be >> vhost-user-net). But we can simply recalculate these two flags in place >> from hdev->features, and from net-client for VHOST_NET_F_VIRTIO_NET_HDR. >> >> Note: removing field from x-query-virtio-status result is incompatible >> change. We can do it because the command is unstable. >> >> Cc: qemu-stable@nongnu.org > > Why do you think this change deserves qemu-stable? Does it fix a bug or > is it just a clean-up? > Oops, it's a mistake (working too late). I wanted to write Cc: devel@lists.libvirt.org :) Seems, v3 is needed anyway, will fix it. -- Best regards, Vladimir
Acked-by: Raphael Norwitz <raphael.s.norwitz@gmail.com>
On Sat, Oct 11, 2025 at 7:24 PM Vladimir Sementsov-Ogievskiy
<vsementsov@yandex-team.ru> wrote:
>
> This field is mostly unused and sometimes confusing (we even have
> a TODO-like comment to drop it). Let's finally do.
>
> The field is used to held VHOST_USER_F_PROTOCOL_FEATURES for vhost-user
> and/or VHOST_NET_F_VIRTIO_NET_HDR for vhost-net (which may be
> vhost-user-net). But we can simply recalculate these two flags in place
> from hdev->features, and from net-client for VHOST_NET_F_VIRTIO_NET_HDR.
>
> Note: removing field from x-query-virtio-status result is incompatible
> change. We can do it because the command is unstable.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> ---
> hw/block/vhost-user-blk.c | 1 -
> hw/net/vhost_net.c | 26 ++++++++++++++------------
> hw/scsi/vhost-scsi.c | 1 -
> hw/scsi/vhost-user-scsi.c | 1 -
> hw/virtio/vdpa-dev.c | 1 -
> hw/virtio/vhost-user.c | 17 ++++++++---------
> hw/virtio/virtio-hmp-cmds.c | 2 --
> hw/virtio/virtio-qmp.c | 4 ----
> include/hw/virtio/vhost.h | 7 -------
> qapi/virtio.json | 3 ---
> 10 files changed, 22 insertions(+), 41 deletions(-)
>
> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> index c0cc5f6942..de7a810c93 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -348,7 +348,6 @@ static int vhost_user_blk_connect(DeviceState *dev, Error **errp)
> s->dev.nvqs = s->num_queues;
> s->dev.vqs = s->vhost_vqs;
> s->dev.vq_index = 0;
> - s->dev.backend_features = 0;
>
> vhost_dev_set_config_notifier(&s->dev, &blk_ops);
>
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 25e9f1fd24..fda90e231e 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -52,8 +52,14 @@ int vhost_net_set_config(struct vhost_net *net, const uint8_t *data,
>
> void vhost_net_ack_features_ex(struct vhost_net *net, const uint64_t *features)
> {
> - virtio_features_copy(net->dev.acked_features_ex,
> - net->dev.backend_features_ex);
> + virtio_features_clear(net->dev.acked_features_ex);
> + if (net->backend == -1) {
> + net->dev.acked_features =
> + net->dev.features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
> + } else if (!qemu_has_vnet_hdr(net->nc)) {
> + net->dev.acked_features = 1ULL << VHOST_NET_F_VIRTIO_NET_HDR;
> + }
> +
> vhost_ack_features_ex(&net->dev, net->feature_bits, features);
> }
>
> @@ -258,12 +264,9 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
> if (r < 0) {
> goto fail;
> }
> - net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend)
> - ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR);
> net->backend = r;
> net->dev.protocol_features = 0;
> } else {
> - virtio_features_clear(net->dev.backend_features_ex);
> net->dev.protocol_features = 0;
> net->backend = -1;
>
> @@ -284,13 +287,12 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
> net->dev.features &= ~(1ULL << VIRTIO_NET_F_MRG_RXBUF);
> }
>
> - if (virtio_features_andnot(missing_features,
> - net->dev.backend_features_ex,
> - net->dev.features_ex)) {
> - fprintf(stderr, "vhost lacks feature mask 0x" VIRTIO_FEATURES_FMT
> - " for backend\n", VIRTIO_FEATURES_PR(missing_features));
> - goto fail;
> - }
> + if (!qemu_has_vnet_hdr(options->net_backend) &&
> + (~net->dev.features & (1ULL << VHOST_NET_F_VIRTIO_NET_HDR))) {
> + fprintf(stderr, "vhost lacks feature mask 0x%llx for backend\n",
> + ~net->dev.features & (1ULL << VHOST_NET_F_VIRTIO_NET_HDR));
> + goto fail;
> + }
> }
>
> /* Set sane init value. Override when guest acks. */
> diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> index cdf405b0f8..d694a25fe2 100644
> --- a/hw/scsi/vhost-scsi.c
> +++ b/hw/scsi/vhost-scsi.c
> @@ -276,7 +276,6 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
> vqs = g_new0(struct vhost_virtqueue, vsc->dev.nvqs);
> vsc->dev.vqs = vqs;
> vsc->dev.vq_index = 0;
> - vsc->dev.backend_features = 0;
>
> ret = vhost_dev_init(&vsc->dev, (void *)(uintptr_t)vhostfd,
> VHOST_BACKEND_TYPE_KERNEL, 0, errp);
> diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
> index 25f2d894e7..0c80a271d8 100644
> --- a/hw/scsi/vhost-user-scsi.c
> +++ b/hw/scsi/vhost-user-scsi.c
> @@ -159,7 +159,6 @@ static int vhost_user_scsi_connect(DeviceState *dev, Error **errp)
> vsc->dev.nvqs = VIRTIO_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
> vsc->dev.vqs = s->vhost_vqs;
> vsc->dev.vq_index = 0;
> - vsc->dev.backend_features = 0;
>
> ret = vhost_dev_init(&vsc->dev, &s->vhost_user, VHOST_BACKEND_TYPE_USER, 0,
> errp);
> diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c
> index 4a7b970976..efd9f68420 100644
> --- a/hw/virtio/vdpa-dev.c
> +++ b/hw/virtio/vdpa-dev.c
> @@ -104,7 +104,6 @@ static void vhost_vdpa_device_realize(DeviceState *dev, Error **errp)
> v->dev.vqs = vqs;
> v->dev.vq_index = 0;
> v->dev.vq_index_end = v->dev.nvqs;
> - v->dev.backend_features = 0;
> v->started = false;
>
> ret = vhost_vdpa_get_iova_range(v->vhostfd, &iova_range);
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index f367ce06ce..b80174f489 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -1448,14 +1448,15 @@ static int vhost_user_set_features(struct vhost_dev *dev,
> int ret;
>
> /*
> - * We need to include any extra backend only feature bits that
> - * might be needed by our device. Currently this includes the
> - * VHOST_USER_F_PROTOCOL_FEATURES bit for enabling protocol
> - * features.
> + * Don't lose VHOST_USER_F_PROTOCOL_FEATURES, which is vhost-user
> + * specific.
> */
> - ret = vhost_user_set_u64(dev, VHOST_USER_SET_FEATURES,
> - features | dev->backend_features,
> - log_enabled);
> + if (virtio_has_feature(dev->features, VHOST_USER_F_PROTOCOL_FEATURES)) {
> + features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
> + }
> +
> + ret = vhost_user_set_u64(dev, VHOST_USER_SET_FEATURES, features,
> + log_enabled);
>
> if (virtio_has_feature(dev->protocol_features,
> VHOST_USER_PROTOCOL_F_STATUS)) {
> @@ -2189,8 +2190,6 @@ static int vhost_user_backend_init(struct vhost_dev *dev, void *opaque,
> (dev->config_ops && dev->config_ops->vhost_dev_config_notifier);
> uint64_t protocol_features;
>
> - dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
> -
> err = vhost_user_get_u64(dev, VHOST_USER_GET_PROTOCOL_FEATURES,
> &protocol_features);
> if (err < 0) {
> diff --git a/hw/virtio/virtio-hmp-cmds.c b/hw/virtio/virtio-hmp-cmds.c
> index 1daae482d3..4bf9a3109d 100644
> --- a/hw/virtio/virtio-hmp-cmds.c
> +++ b/hw/virtio/virtio-hmp-cmds.c
> @@ -176,8 +176,6 @@ void hmp_virtio_status(Monitor *mon, const QDict *qdict)
> hmp_virtio_dump_features(mon, s->vhost_dev->features);
> monitor_printf(mon, " Acked features:\n");
> hmp_virtio_dump_features(mon, s->vhost_dev->acked_features);
> - monitor_printf(mon, " Backend features:\n");
> - hmp_virtio_dump_features(mon, s->vhost_dev->backend_features);
> monitor_printf(mon, " Protocol features:\n");
> hmp_virtio_dump_protocols(mon, s->vhost_dev->protocol_features);
> }
> diff --git a/hw/virtio/virtio-qmp.c b/hw/virtio/virtio-qmp.c
> index b338344c6c..dd1a38e792 100644
> --- a/hw/virtio/virtio-qmp.c
> +++ b/hw/virtio/virtio-qmp.c
> @@ -780,8 +780,6 @@ VirtioStatus *qmp_x_query_virtio_status(const char *path, Error **errp)
> vdev->guest_features_ex);
> status->host_features = qmp_decode_features(vdev->device_id,
> vdev->host_features_ex);
> - status->backend_features = qmp_decode_features(vdev->device_id,
> - vdev->backend_features_ex);
>
> switch (vdev->device_endian) {
> case VIRTIO_DEVICE_ENDIAN_LITTLE:
> @@ -822,8 +820,6 @@ VirtioStatus *qmp_x_query_virtio_status(const char *path, Error **errp)
> qmp_decode_features(vdev->device_id, hdev->features_ex);
> status->vhost_dev->acked_features =
> qmp_decode_features(vdev->device_id, hdev->acked_features_ex);
> - status->vhost_dev->backend_features =
> - qmp_decode_features(vdev->device_id, hdev->backend_features_ex);
>
> status->vhost_dev->protocol_features =
> qmp_decode_protocols(hdev->protocol_features);
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 1ee639dd7e..3e69e47833 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -100,16 +100,9 @@ struct vhost_dev {
> *
> * @features: available features provided by the backend
> * @acked_features: final negotiated features with front-end driver
> - *
> - * @backend_features: this is used in a couple of places to either
> - * store VHOST_USER_F_PROTOCOL_FEATURES to apply to
> - * VHOST_USER_SET_FEATURES or VHOST_NET_F_VIRTIO_NET_HDR. Its
> - * future use should be discouraged and the variable retired as
> - * its easy to confuse with the VirtIO backend_features.
> */
> VIRTIO_DECLARE_FEATURES(features);
> VIRTIO_DECLARE_FEATURES(acked_features);
> - VIRTIO_DECLARE_FEATURES(backend_features);
>
> /**
> * @protocol_features: is the vhost-user only feature set by
> diff --git a/qapi/virtio.json b/qapi/virtio.json
> index 05295ab665..b995a5bb6d 100644
> --- a/qapi/virtio.json
> +++ b/qapi/virtio.json
> @@ -85,8 +85,6 @@
> #
> # @acked-features: vhost_dev acked_features
> #
> -# @backend-features: vhost_dev backend_features
> -#
> # @protocol-features: vhost_dev protocol_features
> #
> # @max-queues: vhost_dev max_queues
> @@ -106,7 +104,6 @@
> 'vq-index': 'int',
> 'features': 'VirtioDeviceFeatures',
> 'acked-features': 'VirtioDeviceFeatures',
> - 'backend-features': 'VirtioDeviceFeatures',
> 'protocol-features': 'VhostDeviceProtocols',
> 'max-queues': 'uint64',
> 'backend-cap': 'uint64',
> --
> 2.48.1
>
Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
> This field is mostly unused and sometimes confusing (we even have
> a TODO-like comment to drop it). Let's finally do.
>
> The field is used to held VHOST_USER_F_PROTOCOL_FEATURES for vhost-user
> and/or VHOST_NET_F_VIRTIO_NET_HDR for vhost-net (which may be
> vhost-user-net). But we can simply recalculate these two flags in place
> from hdev->features, and from net-client for VHOST_NET_F_VIRTIO_NET_HDR.
>
> Note: removing field from x-query-virtio-status result is incompatible
> change. We can do it because the command is unstable.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
You improved the commit message like I suggested, but lost my
Acked-by: Markus Armbruster <armbru@redhat.com>
:)
[...]
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 1ee639dd7e..3e69e47833 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -100,16 +100,9 @@ struct vhost_dev {
> *
> * @features: available features provided by the backend
> * @acked_features: final negotiated features with front-end driver
> - *
> - * @backend_features: this is used in a couple of places to either
> - * store VHOST_USER_F_PROTOCOL_FEATURES to apply to
> - * VHOST_USER_SET_FEATURES or VHOST_NET_F_VIRTIO_NET_HDR. Its
> - * future use should be discouraged and the variable retired as
> - * its easy to confuse with the VirtIO backend_features.
> */
I guess this is the TODO-like comment mentioned in the commit message.
> VIRTIO_DECLARE_FEATURES(features);
> VIRTIO_DECLARE_FEATURES(acked_features);
> - VIRTIO_DECLARE_FEATURES(backend_features);
>
> /**
> * @protocol_features: is the vhost-user only feature set by
> diff --git a/qapi/virtio.json b/qapi/virtio.json
> index 05295ab665..b995a5bb6d 100644
> --- a/qapi/virtio.json
> +++ b/qapi/virtio.json
> @@ -85,8 +85,6 @@
> #
> # @acked-features: vhost_dev acked_features
> #
> -# @backend-features: vhost_dev backend_features
> -#
> # @protocol-features: vhost_dev protocol_features
> #
> # @max-queues: vhost_dev max_queues
> @@ -106,7 +104,6 @@
> 'vq-index': 'int',
> 'features': 'VirtioDeviceFeatures',
> 'acked-features': 'VirtioDeviceFeatures',
> - 'backend-features': 'VirtioDeviceFeatures',
> 'protocol-features': 'VhostDeviceProtocols',
> 'max-queues': 'uint64',
> 'backend-cap': 'uint64',
On 13.10.25 07:42, Markus Armbruster wrote:
> Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:
>
>> This field is mostly unused and sometimes confusing (we even have
>> a TODO-like comment to drop it). Let's finally do.
>>
>> The field is used to held VHOST_USER_F_PROTOCOL_FEATURES for vhost-user
>> and/or VHOST_NET_F_VIRTIO_NET_HDR for vhost-net (which may be
>> vhost-user-net). But we can simply recalculate these two flags in place
>> from hdev->features, and from net-client for VHOST_NET_F_VIRTIO_NET_HDR.
>>
>> Note: removing field from x-query-virtio-status result is incompatible
>> change. We can do it because the command is unstable.
>>
>> Cc: qemu-stable@nongnu.org
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
>
> You improved the commit message like I suggested, but lost my
I decided that commit is changed enough, so that it's not safe to save any r-b/a-b marks.
> Acked-by: Markus Armbruster <armbru@redhat.com>
> :)
Thanks!
>
> [...]
>
>> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
>> index 1ee639dd7e..3e69e47833 100644
>> --- a/include/hw/virtio/vhost.h
>> +++ b/include/hw/virtio/vhost.h
>> @@ -100,16 +100,9 @@ struct vhost_dev {
>> *
>> * @features: available features provided by the backend
>> * @acked_features: final negotiated features with front-end driver
>> - *
>> - * @backend_features: this is used in a couple of places to either
>> - * store VHOST_USER_F_PROTOCOL_FEATURES to apply to
>> - * VHOST_USER_SET_FEATURES or VHOST_NET_F_VIRTIO_NET_HDR. Its
>> - * future use should be discouraged and the variable retired as
>> - * its easy to confuse with the VirtIO backend_features.
>> */
>
> I guess this is the TODO-like comment mentioned in the commit message.
yes)
>
>> VIRTIO_DECLARE_FEATURES(features);
>> VIRTIO_DECLARE_FEATURES(acked_features);
>> - VIRTIO_DECLARE_FEATURES(backend_features);
>>
>> /**
>> * @protocol_features: is the vhost-user only feature set by
>> diff --git a/qapi/virtio.json b/qapi/virtio.json
>> index 05295ab665..b995a5bb6d 100644
>> --- a/qapi/virtio.json
>> +++ b/qapi/virtio.json
>> @@ -85,8 +85,6 @@
>> #
>> # @acked-features: vhost_dev acked_features
>> #
>> -# @backend-features: vhost_dev backend_features
>> -#
>> # @protocol-features: vhost_dev protocol_features
>> #
>> # @max-queues: vhost_dev max_queues
>> @@ -106,7 +104,6 @@
>> 'vq-index': 'int',
>> 'features': 'VirtioDeviceFeatures',
>> 'acked-features': 'VirtioDeviceFeatures',
>> - 'backend-features': 'VirtioDeviceFeatures',
>> 'protocol-features': 'VhostDeviceProtocols',
>> 'max-queues': 'uint64',
>> 'backend-cap': 'uint64',
>
--
Best regards,
Vladimir
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