vhost: relax used address alignment (5d9a07b0) · Commits · 戴 / test

virtio 1.0 only requires used address to be 4 byte aligned, vhost required 8 bytes (size of vring_used_elem). Fix up vhost to match that. Additionally, while vhost correctly requires 8 byte alignment for log, it's unconnected to used ring: it's a consequence that log has u64 entries. Tweak code to make that clearer. Signed-off-by:

Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vhost.c

+7 −3

Original line number	Original line	Diff line number	Diff line
	@@ -713,9 +713,13 @@ long vhost_vring_ioctl(struct vhost_dev d, int ioctl, void __user argp)
	r = -EFAULT;		r = -EFAULT;
	break;		break;
	}		}
	if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) \|\|
	(a.used_user_addr & (sizeof *vq->used->ring - 1)) \|\|		/* Make sure it's safe to cast pointers to vring types. */
	(a.log_guest_addr & (sizeof *vq->used->ring - 1))) {		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 & (sizeof(u64) - 1))) {
	r = -EINVAL;		r = -EINVAL;
	break;		break;
	}		}

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