[RFC PATCH V3 5/6] vhost: factor out setting vring addr and num

[Jason Wang]

Factoring vring address and num setting which needs special care for
accelerating vq metadata accessing.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
 drivers/vhost/vhost.c | 177 ++++++++++++++++++++++++------------------
 1 file changed, 103 insertions(+), 74 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index f3f86c3ed659..c2362ed5839e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1468,6 +1468,104 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
 	return -EFAULT;
 }
 
+static long vhost_vring_set_num(struct vhost_dev *d,
+				struct vhost_virtqueue *vq,
+				void __user *argp)
+{
+	struct vhost_vring_state s;
+
+	/* Resizing ring with an active backend?
+	 * You don't want to do that. */
+	if (vq->private_data)
+		return -EBUSY;
+
+	if (copy_from_user(&s, argp, sizeof s))
+		return -EFAULT;
+
+	if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
+		return -EINVAL;
+	vq->num = s.num;
+
+	return 0;
+}
+
+static long vhost_vring_set_addr(struct vhost_dev *d,
+				 struct vhost_virtqueue *vq,
+				 void __user *argp)
+{
+	struct vhost_vring_addr a;
+
+	if (copy_from_user(&a, argp, sizeof a))
+		return -EFAULT;
+	if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
+		return -EOPNOTSUPP;
+
+	/* For 32bit, verify that the top 32bits of the user
+	   data are set to zero. */
+	if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
+	    (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
+	    (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr)
+		return -EFAULT;
+
+	/* Make sure it's safe to cast pointers to vring types. */
+	BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
+	BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
+	if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
+	    (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
+	    (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
+		return -EINVAL;
+
+	/* We only verify access here if backend is configured.
+	 * 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, 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))
+			return -EINVAL;
+
+		/* Also validate log access for used ring if enabled. */
+		if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
+			!log_access_ok(vq->log_base, a.log_guest_addr,
+				sizeof *vq->used +
+				vq->num * sizeof *vq->used->ring))
+			return -EINVAL;
+	}
+
+	vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
+	vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
+	vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
+	vq->log_addr = a.log_guest_addr;
+	vq->used = (void __user *)(unsigned long)a.used_user_addr;
+
+	return 0;
+}
+
+static long vhost_vring_set_num_addr(struct vhost_dev *d,
+				     struct vhost_virtqueue *vq,
+				     unsigned int ioctl,
+				     void __user *argp)
+{
+	long r;
+
+	mutex_lock(&vq->mutex);
+
+	switch (ioctl) {
+	case VHOST_SET_VRING_NUM:
+		r = vhost_vring_set_num(d, vq, argp);
+		break;
+	case VHOST_SET_VRING_ADDR:
+		r = vhost_vring_set_addr(d, vq, argp);
+		break;
+	default:
+		BUG();
+	}
+
+	mutex_unlock(&vq->mutex);
+
+	return r;
+}
 long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
 {
 	struct file *eventfp, *filep = NULL;
@@ -1477,7 +1575,6 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
 	struct vhost_virtqueue *vq;
 	struct vhost_vring_state s;
 	struct vhost_vring_file f;
-	struct vhost_vring_addr a;
 	u32 idx;
 	long r;
 
@@ -1490,26 +1587,14 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
 	idx = array_index_nospec(idx, d->nvqs);
 	vq = d->vqs[idx];
 
+	if (ioctl == VHOST_SET_VRING_NUM ||
+	    ioctl == VHOST_SET_VRING_ADDR) {
+		return vhost_vring_set_num_addr(d, vq, ioctl, argp);
+	}
+
 	mutex_lock(&vq->mutex);
 
 	switch (ioctl) {
-	case VHOST_SET_VRING_NUM:
-		/* Resizing ring with an active backend?
-		 * You don't want to do that. */
-		if (vq->private_data) {
-			r = -EBUSY;
-			break;
-		}
-		if (copy_from_user(&s, argp, sizeof s)) {
-			r = -EFAULT;
-			break;
-		}
-		if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
-			r = -EINVAL;
-			break;
-		}
-		vq->num = s.num;
-		break;
 	case VHOST_SET_VRING_BASE:
 		/* Moving base with an active backend?
 		 * You don't want to do that. */
@@ -1535,62 +1620,6 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
 		if (copy_to_user(argp, &s, sizeof s))
 			r = -EFAULT;
 		break;
-	case VHOST_SET_VRING_ADDR:
-		if (copy_from_user(&a, argp, sizeof a)) {
-			r = -EFAULT;
-			break;
-		}
-		if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
-			r = -EOPNOTSUPP;
-			break;
-		}
-		/* For 32bit, verify that the top 32bits of the user
-		   data are set to zero. */
-		if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr ||
-		    (u64)(unsigned long)a.used_user_addr != a.used_user_addr ||
-		    (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) {
-			r = -EFAULT;
-			break;
-		}
-
-		/* Make sure it's safe to cast pointers to vring types. */
-		BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
-		BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
-		if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
-		    (a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
-		    (a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1))) {
-			r = -EINVAL;
-			break;
-		}
-
-		/* We only verify access here if backend is configured.
-		 * 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, 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)) {
-				r = -EINVAL;
-				break;
-			}
-
-			/* Also validate log access for used ring if enabled. */
-			if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) &&
-			    !log_access_ok(vq->log_base, a.log_guest_addr,
-					   sizeof *vq->used +
-					   vq->num * sizeof *vq->used->ring)) {
-				r = -EINVAL;
-				break;
-			}
-		}
-
-		vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
-		vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
-		vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
-		vq->log_addr = a.log_guest_addr;
-		vq->used = (void __user *)(unsigned long)a.used_user_addr;
-		break;
 	case VHOST_SET_VRING_KICK:
 		if (copy_from_user(&f, argp, sizeof f)) {
 			r = -EFAULT;
-- 
2.18.1