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-rw-r--r--drivers/xen/xenbus/xenbus_client.c569
1 files changed, 569 insertions, 0 deletions
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
new file mode 100644
index 000000000000..9fd2f70ab46d
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -0,0 +1,569 @@
+/******************************************************************************
+ * Client-facing interface for the Xenbus driver. In other words, the
+ * interface between the Xenbus and the device-specific code, be it the
+ * frontend or the backend of that driver.
+ *
+ * Copyright (C) 2005 XenSource Ltd
+ *
+ * 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.
+ */
+
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/event_channel.h>
+#include <xen/events.h>
+#include <xen/grant_table.h>
+#include <xen/xenbus.h>
+
+const char *xenbus_strstate(enum xenbus_state state)
+{
+ static const char *const name[] = {
+ [ XenbusStateUnknown ] = "Unknown",
+ [ XenbusStateInitialising ] = "Initialising",
+ [ XenbusStateInitWait ] = "InitWait",
+ [ XenbusStateInitialised ] = "Initialised",
+ [ XenbusStateConnected ] = "Connected",
+ [ XenbusStateClosing ] = "Closing",
+ [ XenbusStateClosed ] = "Closed",
+ };
+ return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
+}
+EXPORT_SYMBOL_GPL(xenbus_strstate);
+
+/**
+ * xenbus_watch_path - register a watch
+ * @dev: xenbus device
+ * @path: path to watch
+ * @watch: watch to register
+ * @callback: callback to register
+ *
+ * Register a @watch on the given path, using the given xenbus_watch structure
+ * for storage, and the given @callback function as the callback. Return 0 on
+ * success, or -errno on error. On success, the given @path will be saved as
+ * @watch->node, and remains the caller's to free. On error, @watch->node will
+ * be NULL, the device will switch to %XenbusStateClosing, and the error will
+ * be saved in the store.
+ */
+int xenbus_watch_path(struct xenbus_device *dev, const char *path,
+ struct xenbus_watch *watch,
+ void (*callback)(struct xenbus_watch *,
+ const char **, unsigned int))
+{
+ int err;
+
+ watch->node = path;
+ watch->callback = callback;
+
+ err = register_xenbus_watch(watch);
+
+ if (err) {
+ watch->node = NULL;
+ watch->callback = NULL;
+ xenbus_dev_fatal(dev, err, "adding watch on %s", path);
+ }
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_watch_path);
+
+
+/**
+ * xenbus_watch_pathfmt - register a watch on a sprintf-formatted path
+ * @dev: xenbus device
+ * @watch: watch to register
+ * @callback: callback to register
+ * @pathfmt: format of path to watch
+ *
+ * Register a watch on the given @path, using the given xenbus_watch
+ * structure for storage, and the given @callback function as the callback.
+ * Return 0 on success, or -errno on error. On success, the watched path
+ * (@path/@path2) will be saved as @watch->node, and becomes the caller's to
+ * kfree(). On error, watch->node will be NULL, so the caller has nothing to
+ * free, the device will switch to %XenbusStateClosing, and the error will be
+ * saved in the store.
+ */
+int xenbus_watch_pathfmt(struct xenbus_device *dev,
+ struct xenbus_watch *watch,
+ void (*callback)(struct xenbus_watch *,
+ const char **, unsigned int),
+ const char *pathfmt, ...)
+{
+ int err;
+ va_list ap;
+ char *path;
+
+ va_start(ap, pathfmt);
+ path = kvasprintf(GFP_KERNEL, pathfmt, ap);
+ va_end(ap);
+
+ if (!path) {
+ xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
+ return -ENOMEM;
+ }
+ err = xenbus_watch_path(dev, path, watch, callback);
+
+ if (err)
+ kfree(path);
+ return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_watch_pathfmt);
+
+
+/**
+ * xenbus_switch_state
+ * @dev: xenbus device
+ * @xbt: transaction handle
+ * @state: new state
+ *
+ * Advertise in the store a change of the given driver to the given new_state.
+ * Return 0 on success, or -errno on error. On error, the device will switch
+ * to XenbusStateClosing, and the error will be saved in the store.
+ */
+int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
+{
+ /* We check whether the state is currently set to the given value, and
+ if not, then the state is set. We don't want to unconditionally
+ write the given state, because we don't want to fire watches
+ unnecessarily. Furthermore, if the node has gone, we don't write
+ to it, as the device will be tearing down, and we don't want to
+ resurrect that directory.
+
+ Note that, because of this cached value of our state, this function
+ will not work inside a Xenstore transaction (something it was
+ trying to in the past) because dev->state would not get reset if
+ the transaction was aborted.
+
+ */
+
+ int current_state;
+ int err;
+
+ if (state == dev->state)
+ return 0;
+
+ err = xenbus_scanf(XBT_NIL, dev->nodename, "state", "%d",
+ &current_state);
+ if (err != 1)
+ return 0;
+
+ err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%d", state);
+ if (err) {
+ if (state != XenbusStateClosing) /* Avoid looping */
+ xenbus_dev_fatal(dev, err, "writing new state");
+ return err;
+ }
+
+ dev->state = state;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_switch_state);
+
+int xenbus_frontend_closed(struct xenbus_device *dev)
+{
+ xenbus_switch_state(dev, XenbusStateClosed);
+ complete(&dev->down);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_frontend_closed);
+
+/**
+ * Return the path to the error node for the given device, or NULL on failure.
+ * If the value returned is non-NULL, then it is the caller's to kfree.
+ */
+static char *error_path(struct xenbus_device *dev)
+{
+ return kasprintf(GFP_KERNEL, "error/%s", dev->nodename);
+}
+
+
+static void xenbus_va_dev_error(struct xenbus_device *dev, int err,
+ const char *fmt, va_list ap)
+{
+ int ret;
+ unsigned int len;
+ char *printf_buffer = NULL;
+ char *path_buffer = NULL;
+
+#define PRINTF_BUFFER_SIZE 4096
+ printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL);
+ if (printf_buffer == NULL)
+ goto fail;
+
+ len = sprintf(printf_buffer, "%i ", -err);
+ ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap);
+
+ BUG_ON(len + ret > PRINTF_BUFFER_SIZE-1);
+
+ dev_err(&dev->dev, "%s\n", printf_buffer);
+
+ path_buffer = error_path(dev);
+
+ if (path_buffer == NULL) {
+ dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
+ dev->nodename, printf_buffer);
+ goto fail;
+ }
+
+ if (xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer) != 0) {
+ dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
+ dev->nodename, printf_buffer);
+ goto fail;
+ }
+
+fail:
+ kfree(printf_buffer);
+ kfree(path_buffer);
+}
+
+
+/**
+ * xenbus_dev_error
+ * @dev: xenbus device
+ * @err: error to report
+ * @fmt: error message format
+ *
+ * Report the given negative errno into the store, along with the given
+ * formatted message.
+ */
+void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...)
+{
+ va_list ap;
+
+ va_start(ap, fmt);
+ xenbus_va_dev_error(dev, err, fmt, ap);
+ va_end(ap);
+}
+EXPORT_SYMBOL_GPL(xenbus_dev_error);
+
+/**
+ * xenbus_dev_fatal
+ * @dev: xenbus device
+ * @err: error to report
+ * @fmt: error message format
+ *
+ * Equivalent to xenbus_dev_error(dev, err, fmt, args), followed by
+ * xenbus_switch_state(dev, NULL, XenbusStateClosing) to schedule an orderly
+ * closedown of this driver and its peer.
+ */
+
+void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...)
+{
+ va_list ap;
+
+ va_start(ap, fmt);
+ xenbus_va_dev_error(dev, err, fmt, ap);
+ va_end(ap);
+
+ xenbus_switch_state(dev, XenbusStateClosing);
+}
+EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
+
+/**
+ * xenbus_grant_ring
+ * @dev: xenbus device
+ * @ring_mfn: mfn of ring to grant
+
+ * Grant access to the given @ring_mfn to the peer of the given device. Return
+ * 0 on success, or -errno on error. On error, the device will switch to
+ * XenbusStateClosing, and the error will be saved in the store.
+ */
+int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn)
+{
+ int err = gnttab_grant_foreign_access(dev->otherend_id, ring_mfn, 0);
+ if (err < 0)
+ xenbus_dev_fatal(dev, err, "granting access to ring page");
+ return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_grant_ring);
+
+
+/**
+ * Allocate an event channel for the given xenbus_device, assigning the newly
+ * created local port to *port. Return 0 on success, or -errno on error. On
+ * error, the device will switch to XenbusStateClosing, and the error will be
+ * saved in the store.
+ */
+int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port)
+{
+ struct evtchn_alloc_unbound alloc_unbound;
+ int err;
+
+ alloc_unbound.dom = DOMID_SELF;
+ alloc_unbound.remote_dom = dev->otherend_id;
+
+ err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
+ &alloc_unbound);
+ if (err)
+ xenbus_dev_fatal(dev, err, "allocating event channel");
+ else
+ *port = alloc_unbound.port;
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn);
+
+
+/**
+ * Bind to an existing interdomain event channel in another domain. Returns 0
+ * on success and stores the local port in *port. On error, returns -errno,
+ * switches the device to XenbusStateClosing, and saves the error in XenStore.
+ */
+int xenbus_bind_evtchn(struct xenbus_device *dev, int remote_port, int *port)
+{
+ struct evtchn_bind_interdomain bind_interdomain;
+ int err;
+
+ bind_interdomain.remote_dom = dev->otherend_id;
+ bind_interdomain.remote_port = remote_port;
+
+ err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
+ &bind_interdomain);
+ if (err)
+ xenbus_dev_fatal(dev, err,
+ "binding to event channel %d from domain %d",
+ remote_port, dev->otherend_id);
+ else
+ *port = bind_interdomain.local_port;
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_bind_evtchn);
+
+
+/**
+ * Free an existing event channel. Returns 0 on success or -errno on error.
+ */
+int xenbus_free_evtchn(struct xenbus_device *dev, int port)
+{
+ struct evtchn_close close;
+ int err;
+
+ close.port = port;
+
+ err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
+ if (err)
+ xenbus_dev_error(dev, err, "freeing event channel %d", port);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
+
+
+/**
+ * xenbus_map_ring_valloc
+ * @dev: xenbus device
+ * @gnt_ref: grant reference
+ * @vaddr: pointer to address to be filled out by mapping
+ *
+ * Based on Rusty Russell's skeleton driver's map_page.
+ * Map a page of memory into this domain from another domain's grant table.
+ * xenbus_map_ring_valloc allocates a page of virtual address space, maps the
+ * page to that address, and sets *vaddr to that address.
+ * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
+ * or -ENOMEM on error. If an error is returned, device will switch to
+ * XenbusStateClosing and the error message will be saved in XenStore.
+ */
+int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
+{
+ struct gnttab_map_grant_ref op = {
+ .flags = GNTMAP_host_map,
+ .ref = gnt_ref,
+ .dom = dev->otherend_id,
+ };
+ struct vm_struct *area;
+
+ *vaddr = NULL;
+
+ area = alloc_vm_area(PAGE_SIZE);
+ if (!area)
+ return -ENOMEM;
+
+ op.host_addr = (unsigned long)area->addr;
+
+ if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+ BUG();
+
+ if (op.status != GNTST_okay) {
+ free_vm_area(area);
+ xenbus_dev_fatal(dev, op.status,
+ "mapping in shared page %d from domain %d",
+ gnt_ref, dev->otherend_id);
+ return op.status;
+ }
+
+ /* Stuff the handle in an unused field */
+ area->phys_addr = (unsigned long)op.handle;
+
+ *vaddr = area->addr;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
+
+
+/**
+ * xenbus_map_ring
+ * @dev: xenbus device
+ * @gnt_ref: grant reference
+ * @handle: pointer to grant handle to be filled
+ * @vaddr: address to be mapped to
+ *
+ * Map a page of memory into this domain from another domain's grant table.
+ * xenbus_map_ring does not allocate the virtual address space (you must do
+ * this yourself!). It only maps in the page to the specified address.
+ * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
+ * or -ENOMEM on error. If an error is returned, device will switch to
+ * XenbusStateClosing and the error message will be saved in XenStore.
+ */
+int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
+ grant_handle_t *handle, void *vaddr)
+{
+ struct gnttab_map_grant_ref op = {
+ .host_addr = (unsigned long)vaddr,
+ .flags = GNTMAP_host_map,
+ .ref = gnt_ref,
+ .dom = dev->otherend_id,
+ };
+
+ if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+ BUG();
+
+ if (op.status != GNTST_okay) {
+ xenbus_dev_fatal(dev, op.status,
+ "mapping in shared page %d from domain %d",
+ gnt_ref, dev->otherend_id);
+ } else
+ *handle = op.handle;
+
+ return op.status;
+}
+EXPORT_SYMBOL_GPL(xenbus_map_ring);
+
+
+/**
+ * xenbus_unmap_ring_vfree
+ * @dev: xenbus device
+ * @vaddr: addr to unmap
+ *
+ * Based on Rusty Russell's skeleton driver's unmap_page.
+ * Unmap a page of memory in this domain that was imported from another domain.
+ * Use xenbus_unmap_ring_vfree if you mapped in your memory with
+ * xenbus_map_ring_valloc (it will free the virtual address space).
+ * Returns 0 on success and returns GNTST_* on error
+ * (see xen/include/interface/grant_table.h).
+ */
+int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
+{
+ struct vm_struct *area;
+ struct gnttab_unmap_grant_ref op = {
+ .host_addr = (unsigned long)vaddr,
+ };
+
+ /* It'd be nice if linux/vmalloc.h provided a find_vm_area(void *addr)
+ * method so that we don't have to muck with vmalloc internals here.
+ * We could force the user to hang on to their struct vm_struct from
+ * xenbus_map_ring_valloc, but these 6 lines considerably simplify
+ * this API.
+ */
+ read_lock(&vmlist_lock);
+ for (area = vmlist; area != NULL; area = area->next) {
+ if (area->addr == vaddr)
+ break;
+ }
+ read_unlock(&vmlist_lock);
+
+ if (!area) {
+ xenbus_dev_error(dev, -ENOENT,
+ "can't find mapped virtual address %p", vaddr);
+ return GNTST_bad_virt_addr;
+ }
+
+ op.handle = (grant_handle_t)area->phys_addr;
+
+ if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+ BUG();
+
+ if (op.status == GNTST_okay)
+ free_vm_area(area);
+ else
+ xenbus_dev_error(dev, op.status,
+ "unmapping page at handle %d error %d",
+ (int16_t)area->phys_addr, op.status);
+
+ return op.status;
+}
+EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
+
+
+/**
+ * xenbus_unmap_ring
+ * @dev: xenbus device
+ * @handle: grant handle
+ * @vaddr: addr to unmap
+ *
+ * Unmap a page of memory in this domain that was imported from another domain.
+ * Returns 0 on success and returns GNTST_* on error
+ * (see xen/include/interface/grant_table.h).
+ */
+int xenbus_unmap_ring(struct xenbus_device *dev,
+ grant_handle_t handle, void *vaddr)
+{
+ struct gnttab_unmap_grant_ref op = {
+ .host_addr = (unsigned long)vaddr,
+ .handle = handle,
+ };
+
+ if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+ BUG();
+
+ if (op.status != GNTST_okay)
+ xenbus_dev_error(dev, op.status,
+ "unmapping page at handle %d error %d",
+ handle, op.status);
+
+ return op.status;
+}
+EXPORT_SYMBOL_GPL(xenbus_unmap_ring);
+
+
+/**
+ * xenbus_read_driver_state
+ * @path: path for driver
+ *
+ * Return the state of the driver rooted at the given store path, or
+ * XenbusStateUnknown if no state can be read.
+ */
+enum xenbus_state xenbus_read_driver_state(const char *path)
+{
+ enum xenbus_state result;
+ int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
+ if (err)
+ result = XenbusStateUnknown;
+
+ return result;
+}
+EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
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