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Message-ID: <20210929151119.14778-9-vincent.whitchurch@axis.com>
Date: Wed, 29 Sep 2021 17:11:17 +0200
From: Vincent Whitchurch <vincent.whitchurch@...s.com>
To: <mst@...hat.com>, <jasowang@...hat.com>
CC: <kernel@...s.com>, <kvm@...r.kernel.org>,
<virtualization@...ts.linux-foundation.org>,
<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<pbonzini@...hat.com>, <stefanha@...hat.com>,
<sgarzare@...hat.com>,
Vincent Whitchurch <vincent.whitchurch@...s.com>
Subject: [RFC PATCH 08/10] vhost: net: add support for kernel control
Add support for kernel control to virtio-net. For the vhost-*-kernel
devices, the ioctl to set the backend only provides the socket to
vhost-net but does not start the handling of the virtqueues. The
handling of the virtqueues is started and stopped by the kernel.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---
drivers/vhost/net.c | 106 ++++++++++++++++++++++++++++++++++++++++----
1 file changed, 98 insertions(+), 8 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index b5590b7862a9..977cfa89b216 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -144,6 +144,9 @@ struct vhost_net {
struct page_frag page_frag;
/* Refcount bias of page frag */
int refcnt_bias;
+ /* Used for storing backend sockets when stopped under kernel control */
+ struct socket *tx_sock;
+ struct socket *rx_sock;
};
static unsigned vhost_net_zcopy_mask __read_mostly;
@@ -1293,6 +1296,8 @@ static struct vhost_dev *vhost_net_open(struct vhost *vhost)
n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
if (!n)
return ERR_PTR(-ENOMEM);
+ n->tx_sock = NULL;
+ n->rx_sock = NULL;
vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
if (!vqs) {
kvfree(n);
@@ -1364,6 +1369,20 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
return sock;
}
+/* Stops the virtqueue but doesn't unconsume the tap ring */
+static struct socket *__vhost_net_stop_vq(struct vhost_net *n,
+ struct vhost_virtqueue *vq)
+{
+ struct socket *sock;
+
+ mutex_lock(&vq->mutex);
+ sock = vhost_vq_get_backend(vq);
+ vhost_net_disable_vq(n, vq);
+ vhost_vq_set_backend(vq, NULL);
+ mutex_unlock(&vq->mutex);
+ return sock;
+}
+
static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
struct socket **rx_sock)
{
@@ -1394,6 +1413,57 @@ static void vhost_net_flush(struct vhost_net *n)
}
}
+static void vhost_net_start_vq(struct vhost_net *n, struct vhost_virtqueue *vq,
+ struct socket *sock)
+{
+ mutex_lock(&vq->mutex);
+ vhost_vq_set_backend(vq, sock);
+ vhost_vq_init_access(vq);
+ vhost_net_enable_vq(n, vq);
+ mutex_unlock(&vq->mutex);
+}
+
+static void vhost_net_dev_start_vq(struct vhost_dev *dev, u16 idx)
+{
+ struct vhost_net *n = container_of(dev, struct vhost_net, dev);
+
+ if (WARN_ON(idx >= ARRAY_SIZE(n->vqs)))
+ return;
+
+ if (idx == VHOST_NET_VQ_RX) {
+ vhost_net_start_vq(n, &n->vqs[idx].vq, n->rx_sock);
+ n->rx_sock = NULL;
+ } else if (idx == VHOST_NET_VQ_TX) {
+ vhost_net_start_vq(n, &n->vqs[idx].vq, n->tx_sock);
+ n->tx_sock = NULL;
+ }
+
+ vhost_net_flush_vq(n, idx);
+}
+
+static void vhost_net_dev_stop_vq(struct vhost_dev *dev, u16 idx)
+{
+ struct vhost_net *n = container_of(dev, struct vhost_net, dev);
+ struct socket *sock;
+
+ if (WARN_ON(idx >= ARRAY_SIZE(n->vqs)))
+ return;
+
+ if (!vhost_vq_get_backend(&n->vqs[idx].vq))
+ return;
+
+ sock = __vhost_net_stop_vq(n, &n->vqs[idx].vq);
+
+ vhost_net_flush(n);
+ synchronize_rcu();
+ vhost_net_flush(n);
+
+ if (idx == VHOST_NET_VQ_RX)
+ n->rx_sock = sock;
+ else if (idx == VHOST_NET_VQ_TX)
+ n->tx_sock = sock;
+}
+
static void vhost_net_release(struct vhost_dev *dev)
{
struct vhost_net *n = container_of(dev, struct vhost_net, dev);
@@ -1405,6 +1475,14 @@ static void vhost_net_release(struct vhost_dev *dev)
vhost_dev_stop(&n->dev);
vhost_dev_cleanup(&n->dev);
vhost_net_vq_reset(n);
+ if (n->tx_sock) {
+ WARN_ON(tx_sock);
+ tx_sock = n->tx_sock;
+ }
+ if (n->rx_sock) {
+ WARN_ON(rx_sock);
+ rx_sock = n->rx_sock;
+ }
if (tx_sock)
sockfd_put(tx_sock);
if (rx_sock)
@@ -1518,7 +1596,7 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
mutex_lock(&vq->mutex);
/* Verify that ring has been setup correctly. */
- if (!vhost_vq_access_ok(vq)) {
+ if (!vhost_kernel(vq) && !vhost_vq_access_ok(vq)) {
r = -EFAULT;
goto err_vq;
}
@@ -1539,14 +1617,17 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
}
vhost_net_disable_vq(n, vq);
- vhost_vq_set_backend(vq, sock);
+ if (!vhost_kernel(vq))
+ vhost_vq_set_backend(vq, sock);
vhost_net_buf_unproduce(nvq);
- r = vhost_vq_init_access(vq);
- if (r)
- goto err_used;
- r = vhost_net_enable_vq(n, vq);
- if (r)
- goto err_used;
+ if (!vhost_kernel(vq)) {
+ r = vhost_vq_init_access(vq);
+ if (r)
+ goto err_used;
+ r = vhost_net_enable_vq(n, vq);
+ if (r)
+ goto err_used;
+ }
if (index == VHOST_NET_VQ_RX)
nvq->rx_ring = get_tap_ptr_ring(fd);
@@ -1572,6 +1653,13 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
sockfd_put(oldsock);
}
+ if (vhost_kernel(vq)) {
+ if (index == VHOST_NET_VQ_TX)
+ n->tx_sock = sock;
+ else if (index == VHOST_NET_VQ_RX)
+ n->rx_sock = sock;
+ }
+
return 0;
err_used:
@@ -1733,6 +1821,8 @@ static const struct vhost_ops vhost_net_ops = {
.open = vhost_net_open,
.release = vhost_net_release,
.ioctl = vhost_net_ioctl,
+ .start_vq = vhost_net_dev_start_vq,
+ .stop_vq = vhost_net_dev_stop_vq,
};
static struct vhost *vhost_net;
--
2.28.0
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