* [PATCH] vhost: relax used address alignment
@ 2014-12-20 23:14 Michael S. Tsirkin
0 siblings, 0 replies; only message in thread
From: Michael S. Tsirkin @ 2014-12-20 23:14 UTC (permalink / raw)
To: linux-kernel; +Cc: kvm, virtualization, netdev
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 | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index ed71b53..97996fc 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -713,9 +713,12 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
r = -EFAULT;
break;
}
- if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) ||
- (a.used_user_addr & (sizeof *vq->used->ring - 1)) ||
- (a.log_guest_addr & (sizeof *vq->used->ring - 1))) {
+
+ BUILD_BUG_ON(__alignof__ *vq->avail != 2);
+ BUILD_BUG_ON(__alignof__ *vq->used != 4);
+ if ((a.avail_user_addr & (__alignof__ *vq->avail - 1)) ||
+ (a.used_user_addr & (__alignof__ *vq->used - 1)) ||
+ (a.log_guest_addr & (sizeof(u64) - 1))) {
r = -EINVAL;
break;
}
--
MST
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