static long vhost_vring_set_addr()

in vhost.c [1507:1557]

• 37 lines of code
• 12 McCabe index (conditional complexity)

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 (!vq_log_used_access_ok(vq, vq->log_base,
				a.flags & (0x1 << VHOST_VRING_F_LOG),
				a.log_guest_addr))
			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;
}