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xen-netback: add control ring boilerplate

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My recent patch to include/xen/interface/io/netif.h defines a new shared
ring (in addition to the rx and tx rings) for passing control messages
from a VM frontend driver to a backend driver.

This patch adds the necessary code to xen-netback to map this new shared
ring, should it be created by a frontend, but does not add implementations
for any of the defined protocol messages. These are added in a subsequent
patch for clarity.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paul Durrant 2016-05-13 09:37:26 +01:00 • committed by David S. Miller
parent 1ca4673432
commit 4e15ee2cb4
4 changed files with 277 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

79
drivers/net/xen-netback/xenbus.c
View file

@ -38,7 +38,8 @@ struct backend_info {
const char *hotplug_script;
};
static int connect_rings(struct backend_info *be, struct xenvif_queue *queue);
static int connect_data_rings(struct backend_info *be,
struct xenvif_queue *queue);
static void connect(struct backend_info *be);
static int read_xenbus_vif_flags(struct backend_info *be);
static int backend_create_xenvif(struct backend_info *be);
@ -367,6 +368,12 @@ static int netback_probe(struct xenbus_device *dev,
if (err)
pr_debug("Error writing multi-queue-max-queues\n");
err = xenbus_printf(XBT_NIL, dev->nodename,
"feature-ctrl-ring",
"%u", true);
if (err)
pr_debug("Error writing feature-ctrl-ring\n");
script = xenbus_read(XBT_NIL, dev->nodename, "script", NULL);
if (IS_ERR(script)) {
err = PTR_ERR(script);
@ -457,7 +464,8 @@ static void backend_disconnect(struct backend_info *be)
#ifdef CONFIG_DEBUG_FS
xenvif_debugfs_delif(be->vif);
#endif /* CONFIG_DEBUG_FS */
xenvif_disconnect(be->vif);
xenvif_disconnect_data(be->vif);
xenvif_disconnect_ctrl(be->vif);
}
}
@ -825,6 +833,48 @@ static void hotplug_status_changed(struct xenbus_watch *watch,
kfree(str);
}
static int connect_ctrl_ring(struct backend_info *be)
{
struct xenbus_device *dev = be->dev;
struct xenvif *vif = be->vif;
unsigned int val;
grant_ref_t ring_ref;
unsigned int evtchn;
int err;
err = xenbus_gather(XBT_NIL, dev->otherend,
"ctrl-ring-ref", "%u", &val, NULL);
if (err)
goto done; /* The frontend does not have a control ring */
ring_ref = val;
err = xenbus_gather(XBT_NIL, dev->otherend,
"event-channel-ctrl", "%u", &val, NULL);
if (err) {
xenbus_dev_fatal(dev, err,
"reading %s/event-channel-ctrl",
dev->otherend);
goto fail;
}
evtchn = val;
err = xenvif_connect_ctrl(vif, ring_ref, evtchn);
if (err) {
xenbus_dev_fatal(dev, err,
"mapping shared-frame %u port %u",
ring_ref, evtchn);
goto fail;
}
done:
return 0;
fail:
return err;
}
static void connect(struct backend_info *be)
{
int err;
@ -861,6 +911,12 @@ static void connect(struct backend_info *be)
xen_register_watchers(dev, be->vif);
read_xenbus_vif_flags(be);
err = connect_ctrl_ring(be);
if (err) {
xenbus_dev_fatal(dev, err, "connecting control ring");
return;
}
/* Use the number of queues requested by the frontend */
be->vif->queues = vzalloc(requested_num_queues *
sizeof(struct xenvif_queue));
@ -896,11 +952,12 @@ static void connect(struct backend_info *be)
queue->remaining_credit = credit_bytes;
queue->credit_usec = credit_usec;
err = connect_rings(be, queue);
err = connect_data_rings(be, queue);
if (err) {
/* connect_rings() cleans up after itself on failure,
* but we need to clean up after xenvif_init_queue() here,
* and also clean up any previously initialised queues.
/* connect_data_rings() cleans up after itself on
* failure, but we need to clean up after
* xenvif_init_queue() here, and also clean up any
* previously initialised queues.
*/
xenvif_deinit_queue(queue);
be->vif->num_queues = queue_index;
@ -935,15 +992,17 @@ static void connect(struct backend_info *be)
err:
if (be->vif->num_queues > 0)
xenvif_disconnect(be->vif); /* Clean up existing queues */
xenvif_disconnect_data(be->vif); /* Clean up existing queues */
vfree(be->vif->queues);
be->vif->queues = NULL;
be->vif->num_queues = 0;
xenvif_disconnect_ctrl(be->vif);
return;
}
static int connect_rings(struct backend_info *be, struct xenvif_queue *queue)
static int connect_data_rings(struct backend_info *be,
struct xenvif_queue *queue)
{
struct xenbus_device *dev = be->dev;
unsigned int num_queues = queue->vif->num_queues;
@ -1007,8 +1066,8 @@ static int connect_rings(struct backend_info *be, struct xenvif_queue *queue)
}
/* Map the shared frame, irq etc. */
err = xenvif_connect(queue, tx_ring_ref, rx_ring_ref,
tx_evtchn, rx_evtchn);
err = xenvif_connect_data(queue, tx_ring_ref, rx_ring_ref,
tx_evtchn, rx_evtchn);
if (err) {
xenbus_dev_fatal(dev, err,
"mapping shared-frames %lu/%lu port tx %u rx %u",