KVM: s390: Set virtio-ccw transport revision

With the new SET-VIRTIO-REVISION command of the virtio 1.0 standard, we
can now negotiate the virtio-ccw revision after setting a channel online.

Note that we don't negotiate version 1 yet.

[Cornelia Huck: reworked revision loop a bit]
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 65d0c80236ee..f6eb47b4775b 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -55,6 +55,7 @@ struct virtio_ccw_device {
         struct ccw_device *cdev;
         __u32 curr_io;
         int err;
+        unsigned int revision; /* Transport revision */
         wait_queue_head_t wait_q;
         spinlock_t lock;
         struct list_head virtqueues;
@@ -86,6 +87,15 @@ struct virtio_thinint_area {
         u8 isc;
 } __packed;
 
+struct virtio_rev_info {
+        __u16 revision;
+        __u16 length;
+        __u8 data[];
+};
+
+/* the highest virtio-ccw revision we support */
+#define VIRTIO_CCW_REV_MAX 0
+
 struct virtio_ccw_vq_info {
         struct virtqueue *vq;
         int num;
@@ -122,6 +132,7 @@ static struct airq_info *airq_areas[MAX_AIRQ_AREAS];
 #define CCW_CMD_WRITE_STATUS 0x31
 #define CCW_CMD_READ_VQ_CONF 0x32
 #define CCW_CMD_SET_IND_ADAPTER 0x73
+#define CCW_CMD_SET_VIRTIO_REV 0x83
 
 #define VIRTIO_CCW_DOING_SET_VQ 0x00010000
 #define VIRTIO_CCW_DOING_RESET 0x00040000
@@ -134,6 +145,7 @@ static struct airq_info *airq_areas[MAX_AIRQ_AREAS];
 #define VIRTIO_CCW_DOING_READ_VQ_CONF 0x02000000
 #define VIRTIO_CCW_DOING_SET_CONF_IND 0x04000000
 #define VIRTIO_CCW_DOING_SET_IND_ADAPTER 0x08000000
+#define VIRTIO_CCW_DOING_SET_VIRTIO_REV 0x10000000
 #define VIRTIO_CCW_INTPARM_MASK 0xffff0000
 
 static struct virtio_ccw_device *to_vc_device(struct virtio_device *vdev)
@@ -933,6 +945,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev,
                 case VIRTIO_CCW_DOING_RESET:
                 case VIRTIO_CCW_DOING_READ_VQ_CONF:
                 case VIRTIO_CCW_DOING_SET_IND_ADAPTER:
+                case VIRTIO_CCW_DOING_SET_VIRTIO_REV:
                         vcdev->curr_io &= ~activity;
                         wake_up(&vcdev->wait_q);
                         break;
@@ -1048,6 +1061,51 @@ static int virtio_ccw_offline(struct ccw_device *cdev)
         return 0;
 }
 
+static int virtio_ccw_set_transport_rev(struct virtio_ccw_device *vcdev)
+{
+        struct virtio_rev_info *rev;
+        struct ccw1 *ccw;
+        int ret;
+
+        ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
+        if (!ccw)
+                return -ENOMEM;
+        rev = kzalloc(sizeof(*rev), GFP_DMA | GFP_KERNEL);
+        if (!rev) {
+                kfree(ccw);
+                return -ENOMEM;
+        }
+
+        /* Set transport revision */
+        ccw->cmd_code = CCW_CMD_SET_VIRTIO_REV;
+        ccw->flags = 0;
+        ccw->count = sizeof(*rev);
+        ccw->cda = (__u32)(unsigned long)rev;
+
+        vcdev->revision = VIRTIO_CCW_REV_MAX;
+        do {
+                rev->revision = vcdev->revision;
+                /* none of our supported revisions carry payload */
+                rev->length = 0;
+                ret = ccw_io_helper(vcdev, ccw,
+                                    VIRTIO_CCW_DOING_SET_VIRTIO_REV);
+                if (ret == -EOPNOTSUPP) {
+                        if (vcdev->revision == 0)
+                                /*
+                                 * The host device does not support setting
+                                 * the revision: let's operate it in legacy
+                                 * mode.
+                                 */
+                                ret = 0;
+                        else
+                                vcdev->revision--;
+                }
+        } while (ret == -EOPNOTSUPP);
+
+        kfree(ccw);
+        kfree(rev);
+        return ret;
+}
 
 static int virtio_ccw_online(struct ccw_device *cdev)
 {
@@ -1088,6 +1146,11 @@ static int virtio_ccw_online(struct ccw_device *cdev)
         spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
         vcdev->vdev.id.vendor = cdev->id.cu_type;
         vcdev->vdev.id.device = cdev->id.cu_model;
+
+        ret = virtio_ccw_set_transport_rev(vcdev);
+        if (ret)
+                goto out_free;
+
         ret = register_virtio_device(&vcdev->vdev);
         if (ret) {
                 dev_warn(&cdev->dev, "Failed to register virtio device: %d\n",