vhost: introduce helpers to get the size of metadata area

To avoid code duplication since it will be used by kernel VA prefetching.

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

1 files changed, 33 insertions, 18 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a0f2fbf35a27..30afc79d551e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -428,6 +428,32 @@ bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
 }
 EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
 
+static size_t vhost_get_avail_size(struct vhost_virtqueue *vq,
+                                   unsigned int num)
+{
+        size_t event __maybe_unused =
+               vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
+
+        return sizeof(*vq->avail) +
+               sizeof(*vq->avail->ring) * num + event;
+}
+
+static size_t vhost_get_used_size(struct vhost_virtqueue *vq,
+                                  unsigned int num)
+{
+        size_t event __maybe_unused =
+               vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
+
+        return sizeof(*vq->used) +
+               sizeof(*vq->used->ring) * num + event;
+}
+
+static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
+                                  unsigned int num)
+{
+        return sizeof(*vq->desc) * num;
+}
+
 void vhost_dev_init(struct vhost_dev *dev,
                     struct vhost_virtqueue **vqs, int nvqs,
                     int iov_limit, int weight, int byte_weight)
@@ -1275,13 +1301,9 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
                          struct vring_used __user *used)
 
 {
-        size_t s __maybe_unused = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
-
-        return access_ok(desc, num * sizeof *desc) &&
-               access_ok(avail,
-                         sizeof *avail + num * sizeof *avail->ring + s) &&
-               access_ok(used,
-                        sizeof *used + num * sizeof *used->ring + s);
+        return access_ok(desc, vhost_get_desc_size(vq, num)) &&
+               access_ok(avail, vhost_get_avail_size(vq, num)) &&
+               access_ok(used, vhost_get_used_size(vq, num));
 }
 
 static void vhost_vq_meta_update(struct vhost_virtqueue *vq,
@@ -1333,22 +1355,18 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq,
 
 int vq_meta_prefetch(struct vhost_virtqueue *vq)
 {
-        size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
         unsigned int num = vq->num;
 
         if (!vq->iotlb)
                 return 1;
 
         return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
-                               num * sizeof(*vq->desc), VHOST_ADDR_DESC) &&
+                               vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
                iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->avail,
-                               sizeof *vq->avail +
-                               num * sizeof(*vq->avail->ring) + s,
+                               vhost_get_avail_size(vq, num),
                                VHOST_ADDR_AVAIL) &&
                iotlb_access_ok(vq, VHOST_ACCESS_WO, (u64)(uintptr_t)vq->used,
-                               sizeof *vq->used +
-                               num * sizeof(*vq->used->ring) + s,
-                               VHOST_ADDR_USED);
+                               vhost_get_used_size(vq, num), VHOST_ADDR_USED);
 }
 EXPORT_SYMBOL_GPL(vq_meta_prefetch);
 
@@ -1365,13 +1383,10 @@ EXPORT_SYMBOL_GPL(vhost_log_access_ok);
 static bool vq_log_access_ok(struct vhost_virtqueue *vq,
                              void __user *log_base)
 {
-        size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
-
         return vq_memory_access_ok(log_base, vq->umem,
                                    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));
+                                  vhost_get_used_size(vq, vq->num)));
 }
 
 /* Can we start vq? */