vhost: enable vhost without without MSI-X

We use vhostforce to enable vhost even if Guests don't have MSI-X
support and we fall back to QEMU virtio-net.

This gives a very small performance gain, but the disadvantage
is that guest now controls which virtio code is running
(qemu or vhost) so our attack surface is doubled.

This patch will enable vhost unconditionally whenever it's requested.
For compatibility, enable vhost when vhostforce is set, as well.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>

8 files changed, 4 insertions, 35 deletions

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index f505c91d42..9bd360bd17 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -163,7 +163,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
     net->dev.vq_index = net->nc->queue_index;
 
     r = vhost_dev_init(&net->dev, options->opaque,
-                       options->backend_type, options->force);
+                       options->backend_type);
     if (r < 0) {
         goto fail;
     }
@@ -188,11 +188,6 @@ fail:
     return NULL;
 }
 
-bool vhost_net_query(VHostNetState *net, VirtIODevice *dev)
-{
-    return vhost_dev_query(&net->dev, dev);
-}
-
 static void vhost_net_set_vq_index(struct vhost_net *net, int vq_index)
 {
     net->dev.vq_index = vq_index;
@@ -424,11 +419,6 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
     return NULL;
 }
 
-bool vhost_net_query(VHostNetState *net, VirtIODevice *dev)
-{
-    return false;
-}
-
 int vhost_net_start(VirtIODevice *dev,
                     NetClientState *ncs,
                     int total_queues)
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 9281aa107c..d7282335de 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -128,10 +128,6 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
     if (!n->vhost_started) {
         int r, i;
 
-        if (!vhost_net_query(get_vhost_net(nc->peer), vdev)) {
-            return;
-        }
-
         /* Any packets outstanding? Purge them to avoid touching rings
          * when vhost is running.
          */
diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index 1941aa15c0..1c389c4d7e 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -246,7 +246,7 @@ static void vhost_scsi_realize(DeviceState *dev, Error **errp)
     s->dev.backend_features = 0;
 
     ret = vhost_dev_init(&s->dev, (void *)(uintptr_t)vhostfd,
-                         VHOST_BACKEND_TYPE_KERNEL, true);
+                         VHOST_BACKEND_TYPE_KERNEL);
     if (ret < 0) {
         error_setg(errp, "vhost-scsi: vhost initialization failed: %s",
                    strerror(-ret));
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 7ea45b391c..b84d21cf7e 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -898,7 +898,7 @@ static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
 }
 
 int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
-                   VhostBackendType backend_type, bool force)
+                   VhostBackendType backend_type)
 {
     uint64_t features;
     int i, r;
@@ -961,7 +961,6 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->started = false;
     hdev->memory_changed = false;
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
-    hdev->force = force;
     return 0;
 fail_vq:
     while (--i >= 0) {
@@ -989,17 +988,6 @@ void vhost_dev_cleanup(struct vhost_dev *hdev)
     hdev->vhost_ops->vhost_backend_cleanup(hdev);
 }
 
-bool vhost_dev_query(struct vhost_dev *hdev, VirtIODevice *vdev)
-{
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusState *vbus = VIRTIO_BUS(qbus);
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
-
-    return !k->query_guest_notifiers ||
-           k->query_guest_notifiers(qbus->parent) ||
-           hdev->force;
-}
-
 /* Stop processing guest IO notifications in qemu.
  * Start processing them in vhost in kernel.
  */
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 84f170e789..dd510509eb 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -51,7 +51,6 @@ struct vhost_dev {
     bool log_enabled;
     unsigned long long log_size;
     Error *migration_blocker;
-    bool force;
     bool memory_changed;
     hwaddr mem_changed_start_addr;
     hwaddr mem_changed_end_addr;
@@ -61,7 +60,7 @@ struct vhost_dev {
 };
 
 int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
-                   VhostBackendType backend_type, bool force);
+                   VhostBackendType backend_type);
 void vhost_dev_cleanup(struct vhost_dev *hdev);
 bool vhost_dev_query(struct vhost_dev *hdev, VirtIODevice *vdev);
 int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev);
diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
index 9eb493efc3..840d4b16e2 100644
--- a/include/net/vhost_net.h
+++ b/include/net/vhost_net.h
@@ -11,12 +11,10 @@ typedef struct VhostNetOptions {
     VhostBackendType backend_type;
     NetClientState *net_backend;
     void *opaque;
-    bool force;
 } VhostNetOptions;
 
 struct vhost_net *vhost_net_init(VhostNetOptions *options);
 
-bool vhost_net_query(VHostNetState *net, VirtIODevice *dev);
 int vhost_net_start(VirtIODevice *dev, NetClientState *ncs, int total_queues);
 void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs, int total_queues);
 
diff --git a/net/tap.c b/net/tap.c
index ec12dfd1d8..3a3f522eac 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -671,7 +671,6 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
 
         options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
         options.net_backend = &s->nc;
-        options.force = tap->has_vhostforce && tap->vhostforce;
 
         if (tap->has_vhostfd || tap->has_vhostfds) {
             vhostfd = monitor_fd_param(cur_mon, vhostfdname, &err);
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 8d2672846f..f1df26df95 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -50,7 +50,6 @@ static int vhost_user_start(VhostUserState *s)
     options.backend_type = VHOST_BACKEND_TYPE_USER;
     options.net_backend = &s->nc;
     options.opaque = s->chr;
-    options.force = true;
 
     s->vhost_net = vhost_net_init(&options);