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Subject[PATCH] vhost-vdpa: fix backend feature ioctls
Date
Commit 653055b9acd4 ("vhost-vdpa: support get/set backend features")
introduces two malfunction backend features ioctls:

1) the ioctls was blindly added to vring ioctl instead of vdpa device
ioctl
2) vhost_set_backend_features() was called when dev mutex has already
been held which will lead a deadlock

This patch fixes the above issues.

Cc: Eli Cohen <elic@nvidia.com>
Reported-by: Zhu Lingshan <lingshan.zhu@intel.com>
Fixes: 653055b9acd4 ("vhost-vdpa: support get/set backend features")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/vdpa.c | 30 ++++++++++++++++--------------
1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 3fab94f88894..796fe979f997 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -353,8 +353,6 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
struct vdpa_callback cb;
struct vhost_virtqueue *vq;
struct vhost_vring_state s;
- u64 __user *featurep = argp;
- u64 features;
u32 idx;
long r;

@@ -381,18 +379,6 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,

vq->last_avail_idx = vq_state.avail_index;
break;
- case VHOST_GET_BACKEND_FEATURES:
- features = VHOST_VDPA_BACKEND_FEATURES;
- if (copy_to_user(featurep, &features, sizeof(features)))
- return -EFAULT;
- return 0;
- case VHOST_SET_BACKEND_FEATURES:
- if (copy_from_user(&features, featurep, sizeof(features)))
- return -EFAULT;
- if (features & ~VHOST_VDPA_BACKEND_FEATURES)
- return -EOPNOTSUPP;
- vhost_set_backend_features(&v->vdev, features);
- return 0;
}

r = vhost_vring_ioctl(&v->vdev, cmd, argp);
@@ -440,8 +426,20 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
struct vhost_vdpa *v = filep->private_data;
struct vhost_dev *d = &v->vdev;
void __user *argp = (void __user *)arg;
+ u64 __user *featurep = argp;
+ u64 features;
long r;

+ if (cmd == VHOST_SET_BACKEND_FEATURES) {
+ r = copy_from_user(&features, featurep, sizeof(features));
+ if (r)
+ return r;
+ if (features & ~VHOST_VDPA_BACKEND_FEATURES)
+ return -EOPNOTSUPP;
+ vhost_set_backend_features(&v->vdev, features);
+ return 0;
+ }
+
mutex_lock(&d->mutex);

switch (cmd) {
@@ -476,6 +474,10 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
case VHOST_VDPA_SET_CONFIG_CALL:
r = vhost_vdpa_set_config_call(v, argp);
break;
+ case VHOST_GET_BACKEND_FEATURES:
+ features = VHOST_VDPA_BACKEND_FEATURES;
+ r = copy_to_user(featurep, &features, sizeof(features));
+ break;
default:
r = vhost_dev_ioctl(&v->vdev, cmd, argp);
if (r == -ENOIOCTLCMD)
--
2.20.1
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