Add support for the new avail_event feature in vhost_net
and vhost test modules.

Signed-off-by: Michael S. Tsirkin <[email protected]>
---
 drivers/vhost/net.c   |   12 ++++----
 drivers/vhost/test.c  |    6 ++--
 drivers/vhost/vhost.c |   65 +++++++++++++++++++++++++++++++++++++------------
 drivers/vhost/vhost.h |   17 +++++++------
 4 files changed, 67 insertions(+), 33 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 2f7c76a..e224a92 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -144,7 +144,7 @@ static void handle_tx(struct vhost_net *net)
        }
 
        mutex_lock(&vq->mutex);
-       vhost_disable_notify(vq);
+       vhost_disable_notify(&net->dev, vq);
 
        if (wmem < sock->sk->sk_sndbuf / 2)
                tx_poll_stop(net);
@@ -166,8 +166,8 @@ static void handle_tx(struct vhost_net *net)
                                set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
                                break;
                        }
-                       if (unlikely(vhost_enable_notify(vq))) {
-                               vhost_disable_notify(vq);
+                       if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+                               vhost_disable_notify(&net->dev, vq);
                                continue;
                        }
                        break;
@@ -315,7 +315,7 @@ static void handle_rx(struct vhost_net *net)
                return;
 
        mutex_lock(&vq->mutex);
-       vhost_disable_notify(vq);
+       vhost_disable_notify(&net->dev, vq);
        vhost_hlen = vq->vhost_hlen;
        sock_hlen = vq->sock_hlen;
 
@@ -334,10 +334,10 @@ static void handle_rx(struct vhost_net *net)
                        break;
                /* OK, now we need to know about added descriptors. */
                if (!headcount) {
-                       if (unlikely(vhost_enable_notify(vq))) {
+                       if (unlikely(vhost_enable_notify(&net->dev, vq))) {
                                /* They have slipped one in as we were
                                 * doing that: check again. */
-                               vhost_disable_notify(vq);
+                               vhost_disable_notify(&net->dev, vq);
                                continue;
                        }
                        /* Nothing new?  Wait for eventfd to tell us
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index 099f302..734e1d7 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -49,7 +49,7 @@ static void handle_vq(struct vhost_test *n)
                return;
 
        mutex_lock(&vq->mutex);
-       vhost_disable_notify(vq);
+       vhost_disable_notify(&n->dev, vq);
 
        for (;;) {
                head = vhost_get_vq_desc(&n->dev, vq, vq->iov,
@@ -61,8 +61,8 @@ static void handle_vq(struct vhost_test *n)
                        break;
                /* Nothing new?  Wait for eventfd to tell us they refilled. */
                if (head == vq->num) {
-                       if (unlikely(vhost_enable_notify(vq))) {
-                               vhost_disable_notify(vq);
+                       if (unlikely(vhost_enable_notify(&n->dev, vq))) {
+                               vhost_disable_notify(&n->dev, vq);
                                continue;
                        }
                        break;
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index e33d5a3..2aea4cb 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -38,6 +38,7 @@ enum {
 };
 
 #define vhost_used_event(vq) ((u16 __user *)&vq->avail->ring[vq->num])
+#define vhost_avail_event(vq) ((u16 __user *)&vq->used->ring[vq->num])
 
 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
                            poll_table *pt)
@@ -499,11 +500,12 @@ static int vq_access_ok(struct vhost_dev *d, unsigned int 
num,
                        struct vring_used __user *used)
 {
        size_t sa = vhost_has_feature(d, VIRTIO_RING_F_USED_EVENT_IDX) ? 2 : 0;
+       size_t su = vhost_has_feature(d, VIRTIO_RING_F_AVAIL_EVENT_IDX) ? 2 : 0;
        return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
               access_ok(VERIFY_READ, avail,
                         sizeof *avail + num * sizeof *avail->ring + sa) &&
               access_ok(VERIFY_WRITE, used,
-                       sizeof *used + num * sizeof *used->ring);
+                       sizeof *used + num * sizeof *used->ring + su);
 }
 
 /* Can we log writes? */
@@ -519,9 +521,11 @@ int vhost_log_access_ok(struct vhost_dev *dev)
 
 /* Verify access for write logging. */
 /* Caller should have vq mutex and device mutex */
-static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base)
+static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
+                           void __user *log_base)
 {
        struct vhost_memory *mp;
+       size_t s = vhost_has_feature(d, VIRTIO_RING_F_AVAIL_EVENT_IDX) ? 2 : 0;
 
        mp = rcu_dereference_protected(vq->dev->memory,
                                       lockdep_is_held(&vq->mutex));
@@ -529,7 +533,7 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq, 
void __user *log_base)
                            vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
                (!vq->log_used || log_access_ok(log_base, vq->log_addr,
                                        sizeof *vq->used +
-                                       vq->num * sizeof *vq->used->ring));
+                                       vq->num * sizeof *vq->used->ring + s));
 }
 
 /* Can we start vq? */
@@ -537,7 +541,7 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq, 
void __user *log_base)
 int vhost_vq_access_ok(struct vhost_virtqueue *vq)
 {
        return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
-               vq_log_access_ok(vq, vq->log_base);
+               vq_log_access_ok(vq->dev, vq, vq->log_base);
 }
 
 static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user 
*m)
@@ -824,7 +828,7 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int 
ioctl, unsigned long arg)
                        vq = d->vqs + i;
                        mutex_lock(&vq->mutex);
                        /* If ring is inactive, will check when it's enabled. */
-                       if (vq->private_data && !vq_log_access_ok(vq, base))
+                       if (vq->private_data && !vq_log_access_ok(d, vq, base))
                                r = -EFAULT;
                        else
                                vq->log_base = base;
@@ -1225,6 +1229,10 @@ int vhost_get_vq_desc(struct vhost_dev *dev, struct 
vhost_virtqueue *vq,
 
        /* On success, increment avail index. */
        vq->last_avail_idx++;
+
+       /* Assume notifications from guest are disabled at this point,
+        * if they aren't we would need to update avail_event index. */
+       BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY));
        return head;
 }
 
@@ -1414,7 +1422,7 @@ void vhost_add_used_and_signal_n(struct vhost_dev *dev,
 }
 
 /* OK, now we need to know about added descriptors. */
-bool vhost_enable_notify(struct vhost_virtqueue *vq)
+bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 {
        u16 avail_idx;
        int r;
@@ -1422,11 +1430,34 @@ bool vhost_enable_notify(struct vhost_virtqueue *vq)
        if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
                return false;
        vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
-       r = put_user(vq->used_flags, &vq->used->flags);
-       if (r) {
-               vq_err(vq, "Failed to enable notification at %p: %d\n",
-                      &vq->used->flags, r);
-               return false;
+       if (!vhost_has_feature(dev, VIRTIO_RING_F_AVAIL_EVENT_IDX)) {
+               r = put_user(vq->used_flags, &vq->used->flags);
+               if (r) {
+                       vq_err(vq, "Failed to enable notification at %p: %d\n",
+                              &vq->used->flags, r);
+                       return false;
+               }
+       } else {
+               r = put_user(vq->last_avail_idx, vhost_avail_event(vq));
+               if (r) {
+                       vq_err(vq, "Failed to update avail event index at %p: 
%d\n",
+                              vhost_avail_event(vq), r);
+                       return false;
+               }
+       }
+       if (unlikely(vq->log_used)) {
+               void __user *used;
+               /* Make sure data is seen before log. */
+               smp_wmb();
+               used = vhost_has_feature(dev, VIRTIO_RING_F_AVAIL_EVENT_IDX) ?
+                       &vq->used->flags : vhost_avail_event(vq);
+               /* Log used flags or event index entry write. Both are 16 bit
+                * fields. */
+               log_write(vq->log_base, vq->log_addr +
+                          (used - (void __user *)vq->used),
+                         sizeof(u16));
+               if (vq->log_ctx)
+                       eventfd_signal(vq->log_ctx, 1);
        }
        /* They could have slipped one in as we were doing that: make
         * sure it's written, then check again. */
@@ -1442,15 +1473,17 @@ bool vhost_enable_notify(struct vhost_virtqueue *vq)
 }
 
 /* We don't need to be notified again. */
-void vhost_disable_notify(struct vhost_virtqueue *vq)
+void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 {
        int r;
 
        if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
                return;
        vq->used_flags |= VRING_USED_F_NO_NOTIFY;
-       r = put_user(vq->used_flags, &vq->used->flags);
-       if (r)
-               vq_err(vq, "Failed to enable notification at %p: %d\n",
-                      &vq->used->flags, r);
+       if (!vhost_has_feature(dev, VIRTIO_RING_F_AVAIL_EVENT_IDX)) {
+               r = put_user(vq->used_flags, &vq->used->flags);
+               if (r)
+                       vq_err(vq, "Failed to enable notification at %p: %d\n",
+                              &vq->used->flags, r);
+       }
 }
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 5825ac6..edf84be 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -155,8 +155,8 @@ void vhost_add_used_and_signal(struct vhost_dev *, struct 
vhost_virtqueue *,
 void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
                               struct vring_used_elem *heads, unsigned count);
 void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
-void vhost_disable_notify(struct vhost_virtqueue *);
-bool vhost_enable_notify(struct vhost_virtqueue *);
+void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
+bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 
 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
                    unsigned int log_num, u64 len);
@@ -168,12 +168,13 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct 
vhost_log *log,
        } while (0)
 
 enum {
-       VHOST_FEATURES = (1 << VIRTIO_F_NOTIFY_ON_EMPTY) |
-                        (1 << VIRTIO_RING_F_INDIRECT_DESC) |
-                        (1 << VIRTIO_RING_F_USED_EVENT_IDX) |
-                        (1 << VHOST_F_LOG_ALL) |
-                        (1 << VHOST_NET_F_VIRTIO_NET_HDR) |
-                        (1 << VIRTIO_NET_F_MRG_RXBUF),
+       VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
+                        (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
+                        (1ULL << VIRTIO_RING_F_USED_EVENT_IDX) |
+                        (1ULL << VIRTIO_RING_F_AVAIL_EVENT_IDX) |
+                        (1ULL << VHOST_F_LOG_ALL) |
+                        (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
+                        (1ULL << VIRTIO_NET_F_MRG_RXBUF),
 };
 
 static inline bool vhost_has_feature(struct vhost_dev *dev, int bit)
-- 
1.7.5.53.gc233e

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