diff options
Diffstat (limited to 'drivers/xen/xenbus/xenbus_client.c')
| -rw-r--r-- | drivers/xen/xenbus/xenbus_client.c | 569 |
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 00000000000..9fd2f70ab46 --- /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", + ¤t_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); |