virtio_ccw: add support for 64 bit features.

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>

1 files changed, 23 insertions, 7 deletions

diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 244d611a0df2..65d0c80236ee 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);