From: Alan Cox <alan@xxxxxxxxxxxxxxx>
Subject: [PATCH] vhost: fix warnings on 32 bit systems
Fix compiler warning about discarding top 32 bit
of data on 32 bit systems, and document that
dicarded bits must be 0.
Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
So I think the below slightly tweaked version of
Alan's patch is a bit better. OK?
drivers/vhost/vhost.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 97233d5..e7b4dea 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -322,6 +322,8 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
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) {
@@ -334,7 +336,8 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
r = -EINVAL;
break;
}
- r = init_used(vq, (struct vring_used __user *)a.used_user_addr);
+ r = init_used(vq, (struct vring_used __user *)(unsigned long)
+ a.used_user_addr);
if (r)
break;
vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));
--
1.6.5.2.143.g8cc62
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