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mic: vop: Fix broken virtqueues 

VOP is broken in mainline since commit 1ce9e6055f ("virtio_ring:
introduce packed ring support"); attempting to use the virtqueues leads
to various kernel crashes.  I'm testing it with my not-yet-merged
loopback patches, but even the in-tree MIC hardware cannot work.

The problem is not in the referenced commit per se, but is due to the
following hack in vop_find_vq() which depends on the layout of private
structures in other source files, which that commit happened to change:

  /*
   * To reassign the used ring here we are directly accessing
   * struct vring_virtqueue which is a private data structure
   * in virtio_ring.c. At the minimum, a BUILD_BUG_ON() in
   * vring_new_virtqueue() would ensure that
   *  (&vq->vring == (struct vring *) (&vq->vq + 1));
   */
  vr = (struct vring *)(vq + 1);
  vr->used = used;

Fix vop by using __vring_new_virtqueue() to create the needed vring
layout from the start, instead of attempting to patch in the used ring
later.  __vring_new_virtqueue() was added way back in commit
2a2d1382fe ("virtio: Add improved queue allocation API") in order to
address mic's usecase, according to the commit message.

Fixes: 1ce9e6055f ("virtio_ring: introduce packed ring support")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vincent Whitchurch 2019-01-29 11:22:07 +01:00 committed by Greg Kroah-Hartman
parent cee4c4d63b
commit 5aa608348f
1 changed files with 34 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
drivers/misc/mic/vop/vop_main.c
View File

@ -283,6 +283,26 @@ static void vop_del_vqs(struct virtio_device *dev)
vop_del_vq(vq, idx++);
}
static struct virtqueue *vop_new_virtqueue(unsigned int index,
unsigned int num,
struct virtio_device *vdev,
bool context,
void *pages,
bool (*notify)(struct virtqueue *vq),
void (*callback)(struct virtqueue *vq),
const char *name,
void *used)
{
bool weak_barriers = false;
struct vring vring;
vring_init(&vring, num, pages, MIC_VIRTIO_RING_ALIGN);
vring.used = used;
return __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
notify, callback, name);
}
/*
* This routine will assign vring's allocated in host/io memory. Code in
* virtio_ring.c however continues to access this io memory as if it were local
@ -302,7 +322,6 @@ static struct virtqueue *vop_find_vq(struct virtio_device *dev,
struct _mic_vring_info __iomem *info;
void *used;
int vr_size, _vr_size, err, magic;
struct vring *vr;
u8 type = ioread8(&vdev->desc->type);
if (index >= ioread8(&vdev->desc->num_vq))
@ -322,17 +341,7 @@ static struct virtqueue *vop_find_vq(struct virtio_device *dev,
return ERR_PTR(-ENOMEM);
vdev->vr[index] = va;
memset_io(va, 0x0, _vr_size);
vq = vring_new_virtqueue(
index,
le16_to_cpu(config.num), MIC_VIRTIO_RING_ALIGN,
dev,
false,
ctx,
(void __force *)va, vop_notify, callback, name);
if (!vq) {
err = -ENOMEM;
goto unmap;
}
info = va + _vr_size;
magic = ioread32(&info->magic);
@ -341,7 +350,6 @@ static struct virtqueue *vop_find_vq(struct virtio_device *dev,
goto unmap;
}
/* Allocate and reassign used ring now */
vdev->used_size[index] = PAGE_ALIGN(sizeof(__u16) * 3 +
sizeof(struct vring_used_elem) *
le16_to_cpu(config.num));
@ -351,8 +359,17 @@ static struct virtqueue *vop_find_vq(struct virtio_device *dev,
err = -ENOMEM;
dev_err(_vop_dev(vdev), "%s %d err %d\n",
__func__, __LINE__, err);
goto del_vq;
goto unmap;
}
vq = vop_new_virtqueue(index, le16_to_cpu(config.num), dev, ctx,
(void __force *)va, vop_notify, callback,
name, used);
if (!vq) {
err = -ENOMEM;
goto free_used;
}
vdev->used[index] = dma_map_single(&vpdev->dev, used,
vdev->used_size[index],
DMA_BIDIRECTIONAL);
@ -360,26 +377,17 @@ static struct virtqueue *vop_find_vq(struct virtio_device *dev,
err = -ENOMEM;
dev_err(_vop_dev(vdev), "%s %d err %d\n",
__func__, __LINE__, err);
goto free_used;
goto del_vq;
}
writeq(vdev->used[index], &vqconfig->used_address);
/*
* To reassign the used ring here we are directly accessing
* struct vring_virtqueue which is a private data structure
* in virtio_ring.c. At the minimum, a BUILD_BUG_ON() in
* vring_new_virtqueue() would ensure that
* (&vq->vring == (struct vring *) (&vq->vq + 1));
*/
vr = (struct vring *)(vq + 1);
vr->used = used;
vq->priv = vdev;
return vq;
del_vq:
vring_del_virtqueue(vq);
free_used:
free_pages((unsigned long)used,
get_order(vdev->used_size[index]));
del_vq:
vring_del_virtqueue(vq);
unmap:
vpdev->hw_ops->iounmap(vpdev, vdev->vr[index]);
return ERR_PTR(err);