Virtualization - Sep 2015 - [PATCH 0/1] virtio/s390: one bugfix

Michael,

here's a bugfix for the virtio-ccw driver.

Question: How would you like to get patches? This one is formatted
against your current linux-next branch; I can prepare a branch for
you to pull from as well.

Pierre Morel (1):
  virtio/s390: handle failures of READ_VQ_CONF ccw

 drivers/s390/virtio/virtio_ccw.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

-- 
2.3.8

From: Pierre Morel <pmorel at linux.vnet.ibm.com>

In virtio_ccw_read_vq_conf() the return value of ccw_io_helper()
was not checked.
If the configuration could not be read properly, we'd wrongly assume a
queue size of 0.

Let's propagate any I/O error to virtio_ccw_setup_vq() so it may
properly fail.

Signed-off-by: Pierre Morel <pmorel at linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck at de.ibm.com>
---
 drivers/s390/virtio/virtio_ccw.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index f8d8fdb..e9fae30 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -400,12 +400,16 @@ static bool virtio_ccw_kvm_notify(struct virtqueue *vq)
 static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
 				   struct ccw1 *ccw, int index)
 {
+	int ret;
+
 	vcdev->config_block->index = index;
 	ccw->cmd_code = CCW_CMD_READ_VQ_CONF;
 	ccw->flags = 0;
 	ccw->count = sizeof(struct vq_config_block);
 	ccw->cda = (__u32)(unsigned long)(vcdev->config_block);
-	ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
+	ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
+	if (ret)
+		return ret;
 	return vcdev->config_block->num;
 }
 
@@ -503,6 +507,10 @@ static struct virtqueue *virtio_ccw_setup_vq(struct
virtio_device *vdev,
 		goto out_err;
 	}
 	info->num = virtio_ccw_read_vq_conf(vcdev, ccw, i);
+	if (info->num < 0) {
+		err = info->num;
+		goto out_err;
+	}
 	size = PAGE_ALIGN(vring_size(info->num, KVM_VIRTIO_CCW_RING_ALIGN));
 	info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
 	if (info->queue == NULL) {
-- 
2.3.8

On Thu, Sep 10, 2015 at 04:35:07PM +0200, Cornelia Huck
wrote:
> Michael,
> 
> here's a bugfix for the virtio-ccw driver.
> 
> Question: How would you like to get patches? This one is formatted
> against your current linux-next branch; I can prepare a branch for
> you to pull from as well.
No need, patches are fine.
> Pierre Morel (1):
>   virtio/s390: handle failures of READ_VQ_CONF ccw
> 
>  drivers/s390/virtio/virtio_ccw.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> -- 
> 2.3.8