vhost: fine grain userspace memory accessors

This is used to hide the metadata address from virtqueue helpers. This
will allow to implement a vmap based fast accessing to metadata.

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

1 files changed, 77 insertions, 17 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 3fb58015f8b3..b89faedbb9bd 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -887,6 +887,34 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
         ret; \
 })
 
+static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
+{
+        return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
+                              vhost_avail_event(vq));
+}
+
+static inline int vhost_put_used(struct vhost_virtqueue *vq,
+                                 struct vring_used_elem *head, int idx,
+                                 int count)
+{
+        return vhost_copy_to_user(vq, vq->used->ring + idx, head,
+                                  count * sizeof(*head));
+}
+
+static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
+
+{
+        return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
+                              &vq->used->flags);
+}
+
+static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
+
+{
+        return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
+                              &vq->used->idx);
+}
+
 #define vhost_get_user(vq, x, ptr, type)                \
 ({ \
         int ret; \
@@ -925,6 +953,43 @@ static void vhost_dev_unlock_vqs(struct vhost_dev *d)
                 mutex_unlock(&d->vqs[i]->mutex);
 }
 
+static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
+                                      __virtio16 *idx)
+{
+        return vhost_get_avail(vq, *idx, &vq->avail->idx);
+}
+
+static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
+                                       __virtio16 *head, int idx)
+{
+        return vhost_get_avail(vq, *head,
+                               &vq->avail->ring[idx & (vq->num - 1)]);
+}
+
+static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
+                                        __virtio16 *flags)
+{
+        return vhost_get_avail(vq, *flags, &vq->avail->flags);
+}
+
+static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
+                                       __virtio16 *event)
+{
+        return vhost_get_avail(vq, *event, vhost_used_event(vq));
+}
+
+static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
+                                     __virtio16 *idx)
+{
+        return vhost_get_used(vq, *idx, &vq->used->idx);
+}
+
+static inline int vhost_get_desc(struct vhost_virtqueue *vq,
+                                 struct vring_desc *desc, int idx)
+{
+        return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
+}
+
 static int vhost_new_umem_range(struct vhost_umem *umem,
                                 u64 start, u64 size, u64 end,
                                 u64 userspace_addr, int perm)
@@ -1862,8 +1927,7 @@ EXPORT_SYMBOL_GPL(vhost_log_write);
 static int vhost_update_used_flags(struct vhost_virtqueue *vq)
 {
         void __user *used;
-        if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
-                           &vq->used->flags) < 0)
+        if (vhost_put_used_flags(vq))
                 return -EFAULT;
         if (unlikely(vq->log_used)) {
                 /* Make sure the flag is seen before log. */
@@ -1880,8 +1944,7 @@ static int vhost_update_used_flags(struct vhost_virtqueue *vq)
 
 static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
 {
-        if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
-                           vhost_avail_event(vq)))
+        if (vhost_put_avail_event(vq))
                 return -EFAULT;
         if (unlikely(vq->log_used)) {
                 void __user *used;
@@ -1917,7 +1980,7 @@ int vhost_vq_init_access(struct vhost_virtqueue *vq)
                 r = -EFAULT;
                 goto err;
         }
-        r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
+        r = vhost_get_used_idx(vq, &last_used_idx);
         if (r) {
                 vq_err(vq, "Can't access used idx at %p\n",
                        &vq->used->idx);
@@ -2116,7 +2179,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
         last_avail_idx = vq->last_avail_idx;
 
         if (vq->avail_idx == vq->last_avail_idx) {
-                if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
+                if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
                         vq_err(vq, "Failed to access avail idx at %p\n",
                                 &vq->avail->idx);
                         return -EFAULT;
@@ -2143,8 +2206,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
 
         /* Grab the next descriptor number they're advertising, and increment
          * the index we've seen. */
-        if (unlikely(vhost_get_avail(vq, ring_head,
-                     &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
+        if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
                 vq_err(vq, "Failed to read head: idx %d address %p\n",
                        last_avail_idx,
                        &vq->avail->ring[last_avail_idx % vq->num]);
@@ -2179,8 +2241,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
                                i, vq->num, head);
                         return -EINVAL;
                 }
-                ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
-                                           sizeof desc);
+                ret = vhost_get_desc(vq, &desc, i);
                 if (unlikely(ret)) {
                         vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
                                i, vq->desc + i);
@@ -2273,7 +2334,7 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq,
 
         start = vq->last_used_idx & (vq->num - 1);
         used = vq->used->ring + start;
-        if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
+        if (vhost_put_used(vq, heads, start, count)) {
                 vq_err(vq, "Failed to write used");
                 return -EFAULT;
         }
@@ -2315,8 +2376,7 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
 
         /* Make sure buffer is written before we update index. */
         smp_wmb();
-        if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
-                           &vq->used->idx)) {
+        if (vhost_put_used_idx(vq)) {
                 vq_err(vq, "Failed to increment used idx");
                 return -EFAULT;
         }
@@ -2349,7 +2409,7 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
 
         if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
                 __virtio16 flags;
-                if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
+                if (vhost_get_avail_flags(vq, &flags)) {
                         vq_err(vq, "Failed to get flags");
                         return true;
                 }
@@ -2363,7 +2423,7 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
         if (unlikely(!v))
                 return true;
 
-        if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
+        if (vhost_get_used_event(vq, &event)) {
                 vq_err(vq, "Failed to get used event idx");
                 return true;
         }
@@ -2408,7 +2468,7 @@ bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
         if (vq->avail_idx != vq->last_avail_idx)
                 return false;
 
-        r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
+        r = vhost_get_avail_idx(vq, &avail_idx);
         if (unlikely(r))
                 return false;
         vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
@@ -2444,7 +2504,7 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
         /* They could have slipped one in as we were doing that: make
          * sure it's written, then check again. */
         smp_mb();
-        r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
+        r = vhost_get_avail_idx(vq, &avail_idx);
         if (r) {
                 vq_err(vq, "Failed to check avail idx at %p: %d\n",
                        &vq->avail->idx, r);