vhost: move acked_features to VQs

Refactor code to make sure features are only accessed
under VQ mutex. This makes everything simpler, no need
for RCU here anymore.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

5 files changed, 44 insertions, 42 deletions

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index e489161d0feb..2bc8f298a4e7 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -585,9 +585,9 @@ static void handle_rx(struct vhost_net *net)
         vhost_hlen = nvq->vhost_hlen;
         sock_hlen = nvq->sock_hlen;
 
-        vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
+        vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
                 vq->log : NULL;
-        mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
+        mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
 
         while ((sock_len = peek_head_len(sock->sk))) {
                 sock_len += sock_hlen;
@@ -1051,15 +1051,13 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
                 mutex_unlock(&n->dev.mutex);
                 return -EFAULT;
         }
-        n->dev.acked_features = features;
-        smp_wmb();
         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
                 mutex_lock(&n->vqs[i].vq.mutex);
+                n->vqs[i].vq.acked_features = features;
                 n->vqs[i].vhost_hlen = vhost_hlen;
                 n->vqs[i].sock_hlen = sock_hlen;
                 mutex_unlock(&n->vqs[i].vq.mutex);
         }
-        vhost_net_flush(n);
         mutex_unlock(&n->dev.mutex);
         return 0;
 }
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index cf50ce93975b..f1f284fe30fd 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1373,6 +1373,9 @@ err_dev:
 
 static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
 {
+        struct vhost_virtqueue *vq;
+        int i;
+
         if (features & ~VHOST_SCSI_FEATURES)
                 return -EOPNOTSUPP;
 
@@ -1382,9 +1385,13 @@ static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
                 mutex_unlock(&vs->dev.mutex);
                 return -EFAULT;
         }
-        vs->dev.acked_features = features;
-        smp_wmb();
-        vhost_scsi_flush(vs);
+
+        for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+                vq = &vs->vqs[i].vq;
+                mutex_lock(&vq->mutex);
+                vq->acked_features = features;
+                mutex_unlock(&vq->mutex);
+        }
         mutex_unlock(&vs->dev.mutex);
         return 0;
 }
@@ -1591,10 +1598,6 @@ tcm_vhost_do_plug(struct tcm_vhost_tpg *tpg,
                 return;
 
         mutex_lock(&vs->dev.mutex);
-        if (!vhost_has_feature(&vs->dev, VIRTIO_SCSI_F_HOTPLUG)) {
-                mutex_unlock(&vs->dev.mutex);
-                return;
-        }
 
         if (plug)
                 reason = VIRTIO_SCSI_EVT_RESET_RESCAN;
@@ -1603,8 +1606,9 @@ tcm_vhost_do_plug(struct tcm_vhost_tpg *tpg,
 
         vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
         mutex_lock(&vq->mutex);
-        tcm_vhost_send_evt(vs, tpg, lun,
-                        VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
+        if (vhost_has_feature(vq, VIRTIO_SCSI_F_HOTPLUG))
+                tcm_vhost_send_evt(vs, tpg, lun,
+                                   VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
         mutex_unlock(&vq->mutex);
         mutex_unlock(&vs->dev.mutex);
 }
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index c2a54fbf7f99..6fa3bf8bdec7 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -241,15 +241,18 @@ done:
 
 static int vhost_test_set_features(struct vhost_test *n, u64 features)
 {
+        struct vhost_virtqueue *vq;
+
         mutex_lock(&n->dev.mutex);
         if ((features & (1 << VHOST_F_LOG_ALL)) &&
             !vhost_log_access_ok(&n->dev)) {
                 mutex_unlock(&n->dev.mutex);
                 return -EFAULT;
         }
-        n->dev.acked_features = features;
-        smp_wmb();
-        vhost_test_flush(n);
+        vq = &n->vqs[VHOST_TEST_VQ];
+        mutex_lock(&vq->mutex);
+        vq->acked_features = features;
+        mutex_unlock(&vq->mutex);
         mutex_unlock(&n->dev.mutex);
         return 0;
 }
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 1c05e6030d42..a23870cbbf91 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -191,6 +191,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
         vq->log_used = false;
         vq->log_addr = -1ull;
         vq->private_data = NULL;
+        vq->acked_features = 0;
         vq->log_base = NULL;
         vq->error_ctx = NULL;
         vq->error = NULL;
@@ -524,11 +525,13 @@ static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
 
         for (i = 0; i < d->nvqs; ++i) {
                 int ok;
+                bool log;
+
                 mutex_lock(&d->vqs[i]->mutex);
+                log = log_all || vhost_has_feature(d->vqs[i], VHOST_F_LOG_ALL);
                 /* If ring is inactive, will check when it's enabled. */
                 if (d->vqs[i]->private_data)
-                        ok = vq_memory_access_ok(d->vqs[i]->log_base, mem,
-                                                 log_all);
+                        ok = vq_memory_access_ok(d->vqs[i]->log_base, mem, log);
                 else
                         ok = 1;
                 mutex_unlock(&d->vqs[i]->mutex);
@@ -538,12 +541,12 @@ static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem,
         return 1;
 }
 
-static int vq_access_ok(struct vhost_dev *d, unsigned int num,
+static int vq_access_ok(struct vhost_virtqueue *vq, 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;
+        size_t s = vhost_has_feature(vq, 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 + s) &&
@@ -565,16 +568,16 @@ EXPORT_SYMBOL_GPL(vhost_log_access_ok);
 
 /* Verify access for write logging. */
 /* Caller should have vq mutex and device mutex */
-static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
+static int vq_log_access_ok(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;
+        size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 
         mp = rcu_dereference_protected(vq->dev->memory,
                                        lockdep_is_held(&vq->mutex));
         return vq_memory_access_ok(log_base, mp,
-                            vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
+                                   vhost_has_feature(vq, VHOST_F_LOG_ALL)) &&
                 (!vq->log_used || log_access_ok(log_base, vq->log_addr,
                                         sizeof *vq->used +
                                         vq->num * sizeof *vq->used->ring + s));
@@ -584,8 +587,8 @@ static int vq_log_access_ok(struct vhost_dev *d, struct vhost_virtqueue *vq,
 /* Caller should have vq mutex and device mutex */
 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->dev, vq, vq->log_base);
+        return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
+                vq_log_access_ok(vq, vq->log_base);
 }
 EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
 
@@ -612,8 +615,7 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
                 return -EFAULT;
         }
 
-        if (!memory_access_ok(d, newmem,
-                              vhost_has_feature(d, VHOST_F_LOG_ALL))) {
+        if (!memory_access_ok(d, newmem, 0)) {
                 kfree(newmem);
                 return -EFAULT;
         }
@@ -726,7 +728,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
                  * 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(d, vq->num,
+                        if (!vq_access_ok(vq, 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)) {
@@ -866,7 +868,7 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
                         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(d, vq, base))
+                        if (vq->private_data && !vq_log_access_ok(vq, base))
                                 r = -EFAULT;
                         else
                                 vq->log_base = base;
@@ -1434,11 +1436,11 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
          * interrupts. */
         smp_mb();
 
-        if (vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
+        if (vhost_has_feature(vq, 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)) {
+        if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
                 __u16 flags;
                 if (__get_user(flags, &vq->avail->flags)) {
                         vq_err(vq, "Failed to get flags");
@@ -1499,7 +1501,7 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
         if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
                 return false;
         vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
-        if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
+        if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
                 r = vhost_update_used_flags(vq);
                 if (r) {
                         vq_err(vq, "Failed to enable notification at %p: %d\n",
@@ -1536,7 +1538,7 @@ void vhost_disable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
         if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
                 return;
         vq->used_flags |= VRING_USED_F_NO_NOTIFY;
-        if (!vhost_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) {
+        if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
                 r = vhost_update_used_flags(vq);
                 if (r)
                         vq_err(vq, "Failed to enable notification at %p: %d\n",
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 35eeb2a1bada..ff454a0ec6f5 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -105,6 +105,7 @@ struct vhost_virtqueue {
         struct vring_used_elem *heads;
         /* Protected by virtqueue mutex. */
         void *private_data;
+        unsigned acked_features;
         /* Log write descriptors */
         void __user *log_base;
         struct vhost_log *log;
@@ -117,7 +118,6 @@ struct vhost_dev {
         struct vhost_memory __rcu *memory;
         struct mm_struct *mm;
         struct mutex mutex;
-        unsigned acked_features;
         struct vhost_virtqueue **vqs;
         int nvqs;
         struct file *log_file;
@@ -174,13 +174,8 @@ enum {
                          (1ULL << VHOST_F_LOG_ALL),
 };
 
-static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
+static inline int vhost_has_feature(struct vhost_virtqueue *vq, int bit)
 {
-        unsigned acked_features;
-
-        /* TODO: check that we are running from vhost_worker or dev mutex is
-         * held? */
-        acked_features = rcu_dereference_index_check(dev->acked_features, 1);
-        return acked_features & (1 << bit);
+        return vq->acked_features & (1 << bit);
 }
 #endif