xen: add "not_essential" flag to struct xenbus_driver

When booting the xenbus driver will wait for PV devices to have
connected to their backends before continuing. The timeout is different
between essential and non-essential devices.

Non-essential devices are identified by their nodenames directly in the
xenbus driver, which requires to update this list in case a new device
type being non-essential is added (this was missed for several types
in the past).

In order to avoid this problem, add a "not_essential" flag to struct
xenbus_driver which can be set to "true" by the respective frontend.

Set this flag for the frontends currently regarded to be not essential
(vkbs and vfb) and use it for testing in the xenbus driver.

Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20211022064800.14978-2-jgross@suse.com
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
index 4ff5cd2..3d17a0b 100644 (file)
--- a/drivers/input/misc/xen-kbdfront.c
+++ b/drivers/input/misc/xen-kbdfront.c
@@ -542,6 +542,7 @@ static struct xenbus_driver xenkbd_driver = {
        .remove = xenkbd_remove,
        .resume = xenkbd_resume,
        .otherend_changed = xenkbd_backend_changed,
+       .not_essential = true,
 };
 
 static int __init xenkbd_init(void)

diff --git a/drivers/video/fbdev/xen-fbfront.c b/drivers/video/fbdev/xen-fbfront.c
index 5ec5144..6826f98 100644 (file)
--- a/drivers/video/fbdev/xen-fbfront.c
+++ b/drivers/video/fbdev/xen-fbfront.c
@@ -695,6 +695,7 @@ static struct xenbus_driver xenfb_driver = {
        .remove = xenfb_remove,
        .resume = xenfb_resume,
        .otherend_changed = xenfb_backend_changed,
+       .not_essential = true,
 };
 
 static int __init xenfb_init(void)

diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index 4809446..07b010a 100644 (file)
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -211,19 +211,11 @@ static int is_device_connecting(struct device *dev, void *data, bool ignore_none
        if (drv && (dev->driver != drv))
                return 0;
 
-       if (ignore_nonessential) {
-               /* With older QEMU, for PVonHVM guests the guest config files
-                * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
-                * which is nonsensical as there is no PV FB (there can be
-                * a PVKB) running as HVM guest. */
+       xendrv = to_xenbus_driver(dev->driver);
 
-               if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
-                       return 0;
+       if (ignore_nonessential && xendrv->not_essential)
+               return 0;
 
-               if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
-                       return 0;
-       }
-       xendrv = to_xenbus_driver(dev->driver);
        return (xendev->state < XenbusStateConnected ||
                (xendev->state == XenbusStateConnected &&
                 xendrv->is_ready && !xendrv->is_ready(xendev)));

diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index b94074c..b13eb86 100644 (file)
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -112,6 +112,7 @@ struct xenbus_driver {
        const char *name;       /* defaults to ids[0].devicetype */
        const struct xenbus_device_id *ids;
        bool allow_rebind; /* avoid setting xenstore closed during remove */
+       bool not_essential;     /* is not mandatory for boot progress */
        int (*probe)(struct xenbus_device *dev,
                     const struct xenbus_device_id *id);
        void (*otherend_changed)(struct xenbus_device *dev,