Re: [PATCH v8 06/50] virtio_ccw: add support for 64 bit features.

Thomas Huth
2014-12-02T11:14:32Z

On Mon, 1 Dec 2014 18:03:17 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> Negotiate full 64 bit features.
> Change u32 to u64, make sure to use 1ULL everywhere.
>
> Note: devices guarantee that VERSION_1 is clear unless
> revision 1 is negotiated.
>
> Note: We don't need to re-setup the ccw, but we do it
> for clarity.
>
> Based on patches by Rusty, Thomas Huth and Cornelia.
>
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Reviewed-by: David Hildebrand <dahi@linux.vnet.ibm.com>
> ---
> drivers/s390/kvm/virtio_ccw.c | 30 +++++++++++++++++++++++-------
> 1 file changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
> index 244d611..65d0c80 100644
> --- a/drivers/s390/kvm/virtio_ccw.c
> +++ b/drivers/s390/kvm/virtio_ccw.c
> @@ -664,7 +664,8 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev)
> {
> struct virtio_ccw_device *vcdev = to_vc_device(vdev);
> struct virtio_feature_desc *features;
> - int ret, rc;
> + int ret;
> + u64 rc;
> struct ccw1 *ccw;
>
> ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
> @@ -677,7 +678,6 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev)
> goto out_free;
> }
> /* Read the feature bits from the host. */
> - /* TODO: Features > 32 bits */
> features->index = 0;
> ccw->cmd_code = CCW_CMD_READ_FEAT;
> ccw->flags = 0;
> @@ -691,6 +691,16 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev)
>
> rc = le32_to_cpu(features->features);
>
> + /* Read second half of the feature bits from the host. */
> + features->index = 1;
> + ccw->cmd_code = CCW_CMD_READ_FEAT;
> + ccw->flags = 0;
> + ccw->count = sizeof(*features);
> + ccw->cda = (__u32)(unsigned long)features;
> + ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_FEAT);
> + if (ret == 0)
> + rc |= (u64)le32_to_cpu(features->features) << 32;
> +
> out_free:
> kfree(features);
> kfree(ccw);
> @@ -714,12 +724,18 @@ static void virtio_ccw_finalize_features(struct virtio_device *vdev)
> /* Give virtio_ring a chance to accept features. */
> vring_transport_features(vdev);
>
> - /* Make sure we don't have any features > 32 bits! */
> - BUG_ON((u32)vdev->features != vdev->features);
> -
> features->index = 0;
> - features->features = cpu_to_le32(vdev->features);
> - /* Write the feature bits to the host. */
> + features->features = cpu_to_le32((u32)vdev->features);
> + /* Write the first half of the feature bits to the host. */
> + ccw->cmd_code = CCW_CMD_WRITE_FEAT;
> + ccw->flags = 0;
> + ccw->count = sizeof(*features);
> + ccw->cda = (__u32)(unsigned long)features;
> + ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
> +
> + features->index = 1;
> + features->features = cpu_to_le32(vdev->features >> 32);
> + /* Write the second half of the feature bits to the host. */
> ccw->cmd_code = CCW_CMD_WRITE_FEAT;
> ccw->flags = 0;
> ccw->count = sizeof(*features);

Looks fine!

Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>