VHOST_MEMORY_F_LOG = 0x1,
};
+#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)
{
vq->last_avail_idx = 0;
vq->avail_idx = 0;
vq->last_used_idx = 0;
+ vq->signalled_used = 0;
+ vq->signalled_used_valid = false;
vq->used_flags = 0;
vq->log_used = false;
vq->log_addr = -1ull;
return 1;
}
-static int vq_access_ok(unsigned int num,
+static int vq_access_ok(struct vhost_dev *d, unsigned int num,
struct vring_desc __user *desc,
struct vring_avail __user *avail,
struct vring_used __user *used)
{
+ size_t s = vhost_has_feature(d, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
return access_ok(VERIFY_READ, desc, num * sizeof *desc) &&
access_ok(VERIFY_READ, avail,
- sizeof *avail + num * sizeof *avail->ring) &&
+ sizeof *avail + num * sizeof *avail->ring + s) &&
access_ok(VERIFY_WRITE, used,
- sizeof *used + num * sizeof *used->ring);
+ sizeof *used + num * sizeof *used->ring + s);
}
/* Can we log writes? */
/* 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_EVENT_IDX) ? 2 : 0;
mp = rcu_dereference_protected(vq->dev->memory,
lockdep_is_held(&vq->mutex));
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? */
/* Caller should have vq mutex and device mutex */
int vhost_vq_access_ok(struct vhost_virtqueue *vq)
{
- return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) &&
- vq_log_access_ok(vq, vq->log_base);
+ return vq_access_ok(vq->dev, vq->num, vq->desc, vq->avail, vq->used) &&
+ vq_log_access_ok(vq->dev, vq, vq->log_base);
}
static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
if (r)
return r;
+ vq->signalled_used_valid = false;
return get_user(vq->last_used_idx, &used->idx);
}
* If it is not, we don't as size might not have been setup.
* We will verify when backend is configured. */
if (vq->private_data) {
- if (!vq_access_ok(vq->num,
+ if (!vq_access_ok(d, vq->num,
(void __user *)(unsigned long)a.desc_user_addr,
(void __user *)(unsigned long)a.avail_user_addr,
(void __user *)(unsigned long)a.used_user_addr)) {
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;
/* 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;
}
eventfd_signal(vq->log_ctx, 1);
}
vq->last_used_idx++;
+ /* If the driver never bothers to signal in a very long while,
+ * used index might wrap around. If that happens, invalidate
+ * signalled_used index we stored. TODO: make sure driver
+ * signals at least once in 2^16 and remove this. */
+ if (unlikely(vq->last_used_idx == vq->signalled_used))
+ vq->signalled_used_valid = false;
return 0;
}
unsigned count)
{
struct vring_used_elem __user *used;
+ u16 old, new;
int start;
start = vq->last_used_idx % vq->num;
((void __user *)used - (void __user *)vq->used),
count * sizeof *used);
}
- vq->last_used_idx += count;
+ old = vq->last_used_idx;
+ new = (vq->last_used_idx += count);
+ /* If the driver never bothers to signal in a very long while,
+ * used index might wrap around. If that happens, invalidate
+ * signalled_used index we stored. TODO: make sure driver
+ * signals at least once in 2^16 and remove this. */
+ if (unlikely((u16)(new - vq->signalled_used) < (u16)(new - old)))
+ vq->signalled_used_valid = false;
return 0;
}
return r;
}
-/* This actually signals the guest, using eventfd. */
-void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
{
- __u16 flags;
-
+ __u16 old, new, event;
+ bool v;
/* Flush out used index updates. This is paired
* with the barrier that the Guest executes when enabling
* interrupts. */
smp_mb();
- if (__get_user(flags, &vq->avail->flags)) {
- vq_err(vq, "Failed to get flags");
- return;
+ if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
+ unlikely(vq->avail_idx == vq->last_avail_idx))
+ return true;
+
+ if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
+ __u16 flags;
+ if (__get_user(flags, &vq->avail->flags)) {
+ vq_err(vq, "Failed to get flags");
+ return true;
+ }
+ return !(flags & VRING_AVAIL_F_NO_INTERRUPT);
}
+ old = vq->signalled_used;
+ v = vq->signalled_used_valid;
+ new = vq->signalled_used = vq->last_used_idx;
+ vq->signalled_used_valid = true;
- /* If they don't want an interrupt, don't signal, unless empty. */
- if ((flags & VRING_AVAIL_F_NO_INTERRUPT) &&
- (vq->avail_idx != vq->last_avail_idx ||
- !vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY)))
- return;
+ if (unlikely(!v))
+ return true;
+ if (get_user(event, vhost_used_event(vq))) {
+ vq_err(vq, "Failed to get used event idx");
+ return true;
+ }
+ return vring_need_event(event, new, old);
+}
+
+/* This actually signals the guest, using eventfd. */
+void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq)
+{
/* Signal the Guest tell them we used something up. */
- if (vq->call_ctx)
+ if (vq->call_ctx && vhost_notify(dev, vq))
eventfd_signal(vq->call_ctx, 1);
}
}
/* 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;
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_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->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_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. */
}
/* 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_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);
+ }
}
projects / mv-sheeva.git / blobdiff