xen: add backend driver support

Impact: backend device support

Add the basic machinery to support backend drivers.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
[corresponds to 79727b851bac in git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

7 files changed, 344 insertions, 21 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 10b6bef2e217..84bf17bbb1cd 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -29,6 +29,14 @@ config XEN_DEV_EVTCHN
           firing.
           If in doubt, say yes.
 
+config XEN_BACKEND
+        tristate "Backend driver support"
+        depends on XEN_DOM0
+        default y
+        help
+          Support for backend device drivers that provide I/O services
+          to other virtual machines.
+
 config XENFS
         tristate "Xen filesystem"
         default y
diff --git a/drivers/xen/xenbus/Makefile b/drivers/xen/xenbus/Makefile
index 33e8cf8149b3..8dca685358b4 100644
--- a/drivers/xen/xenbus/Makefile
+++ b/drivers/xen/xenbus/Makefile
@@ -6,4 +6,7 @@ xenbus-objs += xenbus_comms.o
 xenbus-objs += xenbus_xs.o
 xenbus-objs += xenbus_probe.o
 
+xenbus-be-objs-$(CONFIG_XEN_BACKEND) += xenbus_probe_backend.o
+xenbus-objs += $(xenbus-be-objs-y)
+
 obj-$(CONFIG_XEN_XENBUS_FRONTEND) += xenbus_probe_frontend.o
diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index 090c61ee8fd0..700dc7714838 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -49,6 +49,7 @@ static DECLARE_WAIT_QUEUE_HEAD(xb_waitq);
 static irqreturn_t wake_waiting(int irq, void *unused)
 {
         if (unlikely(xenstored_ready == 0)) {
+                printk(KERN_CRIT "xenbus_probe wake_waiting\n");
                 xenstored_ready = 1;
                 schedule_work(&probe_work);
         }
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index d46205868b88..b09eb17ba007 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -95,17 +95,6 @@ int xenbus_match(struct device *_dev, struct device_driver *_drv)
 EXPORT_SYMBOL_GPL(xenbus_match);
 
 
-int xenbus_uevent(struct device *_dev, struct kobj_uevent_env *env)
-{
-        struct xenbus_device *dev = to_xenbus_device(_dev);
-
-        if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
-                return -ENOMEM;
-
-        return 0;
-}
-EXPORT_SYMBOL_GPL(xenbus_uevent);
-
 static void free_otherend_details(struct xenbus_device *dev)
 {
         kfree(dev->otherend);
@@ -690,6 +679,8 @@ void xenbus_probe(struct work_struct *unused)
 {
         xenstored_ready = 1;
 
+        printk(KERN_CRIT "xenbus_probe wake_waiting\n");
+
         /* Notify others that xenstore is up */
         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 }
diff --git a/drivers/xen/xenbus/xenbus_probe.h b/drivers/xen/xenbus/xenbus_probe.h
index be390cef329f..0e5fc4c63eb2 100644
--- a/drivers/xen/xenbus/xenbus_probe.h
+++ b/drivers/xen/xenbus/xenbus_probe.h
@@ -60,7 +60,6 @@ extern int xenbus_probe_devices(struct xen_bus_type *bus);
 
 extern void xenbus_dev_changed(const char *node, struct xen_bus_type *bus);
 
-extern int xenbus_uevent(struct device *_dev, struct kobj_uevent_env *env);
 extern void xenbus_dev_shutdown(struct device *_dev);
 
 extern int xenbus_dev_suspend(struct device *dev, pm_message_t state);
diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c
new file mode 100644
index 000000000000..7459ccee3c8b
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -0,0 +1,300 @@
+/******************************************************************************
+ * Talks to Xen Store to figure out what devices we have (backend half).
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * Copyright (C) 2005 Mike Wray, Hewlett-Packard
+ * Copyright (C) 2005, 2006 XenSource Ltd
+ * Copyright (C) 2007 Solarflare Communications, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define DPRINTK(fmt, args...)                           \
+        pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
+                 __func__, __LINE__, ##args)
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/notifier.h>
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/hypervisor.h>
+#include <xen/xenbus.h>
+#include <xen/evtchn.h>
+#include <xen/features.h>
+
+#include "xenbus_comms.h"
+#include "xenbus_probe.h"
+
+/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
+static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
+{
+        int domid, err;
+        const char *devid, *type, *frontend;
+        unsigned int typelen;
+
+        type = strchr(nodename, '/');
+        if (!type)
+                return -EINVAL;
+        type++;
+        typelen = strcspn(type, "/");
+        if (!typelen || type[typelen] != '/')
+                return -EINVAL;
+
+        devid = strrchr(nodename, '/') + 1;
+
+        err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
+                            "frontend", NULL, &frontend,
+                            NULL);
+        if (err)
+                return err;
+        if (strlen(frontend) == 0)
+                err = -ERANGE;
+        if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
+                err = -ENOENT;
+        kfree(frontend);
+
+        if (err)
+                return err;
+
+        if (snprintf(bus_id, XEN_BUS_ID_SIZE,
+                     "%.*s-%i-%s", typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
+                return -ENOSPC;
+        return 0;
+}
+
+static int xenbus_uevent_backend(struct device *dev,
+                                 struct kobj_uevent_env *env)
+{
+        struct xenbus_device *xdev;
+        struct xenbus_driver *drv;
+        struct xen_bus_type *bus;
+
+        DPRINTK("");
+
+        if (dev == NULL)
+                return -ENODEV;
+
+        xdev = to_xenbus_device(dev);
+        bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
+        if (xdev == NULL)
+                return -ENODEV;
+
+        /* stuff we want to pass to /sbin/hotplug */
+        if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
+                return -ENOMEM;
+
+        if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
+                return -ENOMEM;
+
+        if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
+                return -ENOMEM;
+
+        if (dev->driver) {
+                drv = to_xenbus_driver(dev->driver);
+                if (drv && drv->uevent)
+                        return drv->uevent(xdev, env);
+        }
+
+        return 0;
+}
+
+/* backend/<typename>/<frontend-uuid>/<name> */
+static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
+                                     const char *dir,
+                                     const char *type,
+                                     const char *name)
+{
+        char *nodename;
+        int err;
+
+        nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
+        if (!nodename)
+                return -ENOMEM;
+
+        DPRINTK("%s\n", nodename);
+
+        err = xenbus_probe_node(bus, type, nodename);
+        kfree(nodename);
+        return err;
+}
+
+/* backend/<typename>/<frontend-domid> */
+static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type, const char *domid)
+{
+        char *nodename;
+        int err = 0;
+        char **dir;
+        unsigned int i, dir_n = 0;
+
+        DPRINTK("");
+
+        nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
+        if (!nodename)
+                return -ENOMEM;
+
+        dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
+        if (IS_ERR(dir)) {
+                kfree(nodename);
+                return PTR_ERR(dir);
+        }
+
+        for (i = 0; i < dir_n; i++) {
+                err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
+                if (err)
+                        break;
+        }
+        kfree(dir);
+        kfree(nodename);
+        return err;
+}
+
+static void frontend_changed(struct xenbus_watch *watch,
+                            const char **vec, unsigned int len)
+{
+        xenbus_otherend_changed(watch, vec, len, 0);
+}
+
+static struct device_attribute xenbus_backend_dev_attrs[] = {
+        __ATTR_NULL
+};
+
+static struct xen_bus_type xenbus_backend = {
+        .root = "backend",
+        .levels = 3,            /* backend/type/<frontend>/<id> */
+        .get_bus_id = backend_bus_id,
+        .probe = xenbus_probe_backend,
+        .otherend_changed = frontend_changed,
+        .bus = {
+                .name      = "xen-backend",
+                .match     = xenbus_match,
+                .uevent    = xenbus_uevent_backend,
+                .probe     = xenbus_dev_probe,
+                .remove    = xenbus_dev_remove,
+                .shutdown  = xenbus_dev_shutdown,
+                .dev_attrs = xenbus_backend_dev_attrs,
+        },
+};
+
+static void backend_changed(struct xenbus_watch *watch,
+                            const char **vec, unsigned int len)
+{
+        DPRINTK("");
+
+        xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
+}
+
+static struct xenbus_watch be_watch = {
+        .node = "backend",
+        .callback = backend_changed,
+};
+
+static int read_frontend_details(struct xenbus_device *xendev)
+{
+        return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
+}
+
+//void xenbus_backend_suspend(int (*fn)(struct device *, void *))
+//{
+//      DPRINTK("");
+//      bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, fn);
+//}
+
+//void xenbus_backend_resume(int (*fn)(struct device *, void *))
+//{
+//      DPRINTK("");
+//      bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, fn);
+//}
+
+//int xenbus_for_each_backend(void *arg, int (*fn)(struct device *, void *))
+//{
+//      return bus_for_each_dev(&xenbus_backend.bus, NULL, arg, fn);
+//}
+//EXPORT_SYMBOL_GPL(xenbus_for_each_backend);
+
+int xenbus_dev_is_online(struct xenbus_device *dev)
+{
+        int rc, val;
+
+        rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
+        if (rc != 1)
+                val = 0; /* no online node present */
+
+        return val;
+}
+EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
+
+int __xenbus_register_backend(struct xenbus_driver *drv,
+                              struct module *owner, const char *mod_name)
+{
+        drv->read_otherend_details = read_frontend_details;
+
+        return xenbus_register_driver_common(drv, &xenbus_backend,
+                                             owner, mod_name);
+}
+EXPORT_SYMBOL_GPL(__xenbus_register_backend);
+
+static int backend_probe_and_watch(struct notifier_block *notifier,
+                                   unsigned long event,
+                                   void *data)
+{
+        /* Enumerate devices in xenstore and watch for changes. */
+        xenbus_probe_devices(&xenbus_backend);
+        printk(KERN_CRIT "%s devices probed ok\n", __func__);
+        register_xenbus_watch(&be_watch);
+        printk(KERN_CRIT "%s watch add ok ok\n", __func__);
+        printk(KERN_CRIT "%s all done\n", __func__);
+        return NOTIFY_DONE;
+}
+
+static int __init xenbus_probe_backend_init(void)
+{
+        static struct notifier_block xenstore_notifier = {
+                .notifier_call = backend_probe_and_watch
+        };
+        int err;
+
+        DPRINTK("");
+
+        /* Register ourselves with the kernel bus subsystem */
+        err = bus_register(&xenbus_backend.bus);
+        if (err) {
+                printk(KERN_CRIT "%s didn't register bus!\n", __func__);
+                return err;
+        }
+        printk(KERN_CRIT "%s bus registered ok\n", __func__);
+
+        register_xenstore_notifier(&xenstore_notifier);
+
+        return 0;
+}
+
+module_init(xenbus_probe_backend_init);
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
index 04c4f0123521..dd31d5a43b40 100644
--- a/drivers/xen/xenbus/xenbus_probe_frontend.c
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -62,6 +62,17 @@ static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type, con
         return err;
 }
 
+static int xenbus_uevent_frontend(struct device *_dev, struct kobj_uevent_env *env)
+{
+        struct xenbus_device *dev = to_xenbus_device(_dev);
+
+        if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
+                return -ENOMEM;
+
+        return 0;
+}
+
+
 static void backend_changed(struct xenbus_watch *watch,
                             const char **vec, unsigned int len)
 {
@@ -81,7 +92,7 @@ static struct xen_bus_type xenbus_frontend = {
         .bus = {
                 .name     = "xen",
                 .match    = xenbus_match,
-                .uevent   = xenbus_uevent,
+                .uevent   = xenbus_uevent_frontend,
                 .probe    = xenbus_dev_probe,
                 .remove   = xenbus_dev_remove,
                 .shutdown = xenbus_dev_shutdown,
@@ -232,8 +243,25 @@ int __xenbus_register_frontend(struct xenbus_driver *drv,
 }
 EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
 
+static int frontend_probe_and_watch(struct notifier_block *notifier,
+                                   unsigned long event,
+                                   void *data)
+{
+        /* Enumerate devices in xenstore and watch for changes. */
+        xenbus_probe_devices(&xenbus_frontend);
+        printk(KERN_CRIT "%s devices probed ok\n", __func__);
+        register_xenbus_watch(&fe_watch);
+        printk(KERN_CRIT "%s watch add ok ok\n", __func__);
+        printk(KERN_CRIT "%s all done\n", __func__);
+        return NOTIFY_DONE;
+}
+
+
 static int __init xenbus_probe_frontend_init(void)
 {
+        static struct notifier_block xenstore_notifier = {
+                .notifier_call = frontend_probe_and_watch
+        };
         int err;
 
         DPRINTK("");
@@ -246,14 +274,7 @@ static int __init xenbus_probe_frontend_init(void)
         }
         printk(KERN_CRIT "%s bus registered ok\n", __func__);
 
-        if (!xen_initial_domain()) {
-                /* Enumerate devices in xenstore and watch for changes. */
-                xenbus_probe_devices(&xenbus_frontend);
-                printk(KERN_CRIT "%s devices probed ok\n", __func__);
-                register_xenbus_watch(&fe_watch);
-                printk(KERN_CRIT "%s watch add ok ok\n", __func__);
-                printk(KERN_CRIT "%s all done\n", __func__);
-        }
+        register_xenstore_notifier(&xenstore_notifier);
 
         return 0;
 }