4 * Copyright (C) 2012 VMware, Inc. All rights reserved.
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation version 2 and no later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
12 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 #include <linux/vmw_vmci_defs.h>
17 #include <linux/vmw_vmci_api.h>
18 #include <linux/completion.h>
19 #include <linux/hash.h>
20 #include <linux/kernel.h>
21 #include <linux/list.h>
22 #include <linux/module.h>
23 #include <linux/sched.h>
24 #include <linux/slab.h>
26 #include "vmci_datagram.h"
27 #include "vmci_doorbell.h"
28 #include "vmci_resource.h"
29 #include "vmci_driver.h"
30 #include "vmci_route.h"
33 #define VMCI_DOORBELL_INDEX_BITS 6
34 #define VMCI_DOORBELL_INDEX_TABLE_SIZE (1 << VMCI_DOORBELL_INDEX_BITS)
35 #define VMCI_DOORBELL_HASH(_idx) hash_32(_idx, VMCI_DOORBELL_INDEX_BITS)
38 * DoorbellEntry describes the a doorbell notification handle allocated by the
42 struct vmci_resource resource;
43 struct hlist_node node;
44 struct work_struct work;
45 vmci_callback notify_cb;
50 atomic_t active; /* Only used by guest personality */
53 /* The VMCI index table keeps track of currently registered doorbells. */
54 struct dbell_index_table {
55 spinlock_t lock; /* Index table lock */
56 struct hlist_head entries[VMCI_DOORBELL_INDEX_TABLE_SIZE];
59 static struct dbell_index_table vmci_doorbell_it = {
60 .lock = __SPIN_LOCK_UNLOCKED(vmci_doorbell_it.lock),
64 * The max_notify_idx is one larger than the currently known bitmap index in
65 * use, and is used to determine how much of the bitmap needs to be scanned.
67 static u32 max_notify_idx;
70 * The notify_idx_count is used for determining whether there are free entries
71 * within the bitmap (if notify_idx_count + 1 < max_notify_idx).
73 static u32 notify_idx_count;
76 * The last_notify_idx_reserved is used to track the last index handed out - in
77 * the case where multiple handles share a notification index, we hand out
78 * indexes round robin based on last_notify_idx_reserved.
80 static u32 last_notify_idx_reserved;
82 /* This is a one entry cache used to by the index allocation. */
83 static u32 last_notify_idx_released = PAGE_SIZE;
87 * Utility function that retrieves the privilege flags associated
88 * with a given doorbell handle. For guest endpoints, the
89 * privileges are determined by the context ID, but for host
90 * endpoints privileges are associated with the complete
91 * handle. Hypervisor endpoints are not yet supported.
93 int vmci_dbell_get_priv_flags(struct vmci_handle handle, u32 *priv_flags)
95 if (priv_flags == NULL || handle.context == VMCI_INVALID_ID)
96 return VMCI_ERROR_INVALID_ARGS;
98 if (handle.context == VMCI_HOST_CONTEXT_ID) {
99 struct dbell_entry *entry;
100 struct vmci_resource *resource;
102 resource = vmci_resource_by_handle(handle,
103 VMCI_RESOURCE_TYPE_DOORBELL);
105 return VMCI_ERROR_NOT_FOUND;
107 entry = container_of(resource, struct dbell_entry, resource);
108 *priv_flags = entry->priv_flags;
109 vmci_resource_put(resource);
110 } else if (handle.context == VMCI_HYPERVISOR_CONTEXT_ID) {
112 * Hypervisor endpoints for notifications are not
115 return VMCI_ERROR_INVALID_ARGS;
117 *priv_flags = vmci_context_get_priv_flags(handle.context);
124 * Find doorbell entry by bitmap index.
126 static struct dbell_entry *dbell_index_table_find(u32 idx)
128 u32 bucket = VMCI_DOORBELL_HASH(idx);
129 struct dbell_entry *dbell;
130 struct hlist_node *node;
132 hlist_for_each_entry(dbell, node, &vmci_doorbell_it.entries[bucket],
134 if (idx == dbell->idx)
142 * Add the given entry to the index table. This willi take a reference to the
143 * entry's resource so that the entry is not deleted before it is removed from
146 static void dbell_index_table_add(struct dbell_entry *entry)
151 vmci_resource_get(&entry->resource);
153 spin_lock_bh(&vmci_doorbell_it.lock);
156 * Below we try to allocate an index in the notification
157 * bitmap with "not too much" sharing between resources. If we
158 * use less that the full bitmap, we either add to the end if
159 * there are no unused flags within the currently used area,
160 * or we search for unused ones. If we use the full bitmap, we
161 * allocate the index round robin.
163 if (max_notify_idx < PAGE_SIZE || notify_idx_count < PAGE_SIZE) {
164 if (last_notify_idx_released < max_notify_idx &&
165 !dbell_index_table_find(last_notify_idx_released)) {
166 new_notify_idx = last_notify_idx_released;
167 last_notify_idx_released = PAGE_SIZE;
170 new_notify_idx = last_notify_idx_reserved;
171 if (notify_idx_count + 1 < max_notify_idx) {
173 if (!dbell_index_table_find
178 new_notify_idx = (new_notify_idx + 1) %
180 } while (new_notify_idx !=
181 last_notify_idx_released);
184 new_notify_idx = max_notify_idx;
189 new_notify_idx = (last_notify_idx_reserved + 1) % PAGE_SIZE;
192 last_notify_idx_reserved = new_notify_idx;
195 entry->idx = new_notify_idx;
196 bucket = VMCI_DOORBELL_HASH(entry->idx);
197 hlist_add_head(&entry->node, &vmci_doorbell_it.entries[bucket]);
199 spin_unlock_bh(&vmci_doorbell_it.lock);
203 * Remove the given entry from the index table. This will release() the
206 static void dbell_index_table_remove(struct dbell_entry *entry)
208 spin_lock_bh(&vmci_doorbell_it.lock);
210 hlist_del_init(&entry->node);
213 if (entry->idx == max_notify_idx - 1) {
215 * If we delete an entry with the maximum known
216 * notification index, we take the opportunity to
217 * prune the current max. As there might be other
218 * unused indices immediately below, we lower the
219 * maximum until we hit an index in use.
221 while (max_notify_idx > 0 &&
222 !dbell_index_table_find(max_notify_idx - 1))
226 last_notify_idx_released = entry->idx;
228 spin_unlock_bh(&vmci_doorbell_it.lock);
230 vmci_resource_put(&entry->resource);
234 * Creates a link between the given doorbell handle and the given
235 * index in the bitmap in the device backend. A notification state
236 * is created in hypervisor.
238 static int dbell_link(struct vmci_handle handle, u32 notify_idx)
240 struct vmci_doorbell_link_msg link_msg;
242 link_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
244 link_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
245 link_msg.hdr.payload_size = sizeof(link_msg) - VMCI_DG_HEADERSIZE;
246 link_msg.handle = handle;
247 link_msg.notify_idx = notify_idx;
249 return vmci_send_datagram(&link_msg.hdr);
253 * Unlinks the given doorbell handle from an index in the bitmap in
254 * the device backend. The notification state is destroyed in hypervisor.
256 static int dbell_unlink(struct vmci_handle handle)
258 struct vmci_doorbell_unlink_msg unlink_msg;
260 unlink_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
261 VMCI_DOORBELL_UNLINK);
262 unlink_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
263 unlink_msg.hdr.payload_size = sizeof(unlink_msg) - VMCI_DG_HEADERSIZE;
264 unlink_msg.handle = handle;
266 return vmci_send_datagram(&unlink_msg.hdr);
270 * Notify another guest or the host. We send a datagram down to the
271 * host via the hypervisor with the notification info.
273 static int dbell_notify_as_guest(struct vmci_handle handle, u32 priv_flags)
275 struct vmci_doorbell_notify_msg notify_msg;
277 notify_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
278 VMCI_DOORBELL_NOTIFY);
279 notify_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
280 notify_msg.hdr.payload_size = sizeof(notify_msg) - VMCI_DG_HEADERSIZE;
281 notify_msg.handle = handle;
283 return vmci_send_datagram(¬ify_msg.hdr);
287 * Calls the specified callback in a delayed context.
289 static void dbell_delayed_dispatch(struct work_struct *work)
291 struct dbell_entry *entry = container_of(work,
292 struct dbell_entry, work);
294 entry->notify_cb(entry->client_data);
295 vmci_resource_put(&entry->resource);
299 * Dispatches a doorbell notification to the host context.
301 int vmci_dbell_host_context_notify(u32 src_cid, struct vmci_handle handle)
303 struct dbell_entry *entry;
304 struct vmci_resource *resource;
306 if (vmci_handle_is_invalid(handle)) {
307 pr_devel("Notifying an invalid doorbell (handle=0x%x:0x%x)\n",
308 handle.context, handle.resource);
309 return VMCI_ERROR_INVALID_ARGS;
312 resource = vmci_resource_by_handle(handle,
313 VMCI_RESOURCE_TYPE_DOORBELL);
315 pr_devel("Notifying an unknown doorbell (handle=0x%x:0x%x)\n",
316 handle.context, handle.resource);
317 return VMCI_ERROR_NOT_FOUND;
320 entry = container_of(resource, struct dbell_entry, resource);
321 if (entry->run_delayed) {
322 schedule_work(&entry->work);
324 entry->notify_cb(entry->client_data);
325 vmci_resource_put(resource);
332 * Register the notification bitmap with the host.
334 bool vmci_dbell_register_notification_bitmap(u32 bitmap_ppn)
337 struct vmci_notify_bm_set_msg bitmap_set_msg;
339 bitmap_set_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID,
340 VMCI_SET_NOTIFY_BITMAP);
341 bitmap_set_msg.hdr.src = VMCI_ANON_SRC_HANDLE;
342 bitmap_set_msg.hdr.payload_size = sizeof(bitmap_set_msg) -
344 bitmap_set_msg.bitmap_ppn = bitmap_ppn;
346 result = vmci_send_datagram(&bitmap_set_msg.hdr);
347 if (result != VMCI_SUCCESS) {
348 pr_devel("Failed to register (PPN=%u) as notification bitmap (error=%d)\n",
356 * Executes or schedules the handlers for a given notify index.
358 static void dbell_fire_entries(u32 notify_idx)
360 u32 bucket = VMCI_DOORBELL_HASH(notify_idx);
361 struct dbell_entry *dbell;
362 struct hlist_node *node;
364 spin_lock_bh(&vmci_doorbell_it.lock);
366 hlist_for_each_entry(dbell, node,
367 &vmci_doorbell_it.entries[bucket], node) {
368 if (dbell->idx == notify_idx &&
369 atomic_read(&dbell->active) == 1) {
370 if (dbell->run_delayed) {
371 vmci_resource_get(&dbell->resource);
372 schedule_work(&dbell->work);
374 dbell->notify_cb(dbell->client_data);
379 spin_unlock_bh(&vmci_doorbell_it.lock);
383 * Scans the notification bitmap, collects pending notifications,
384 * resets the bitmap and invokes appropriate callbacks.
386 void vmci_dbell_scan_notification_entries(u8 *bitmap)
390 for (idx = 0; idx < max_notify_idx; idx++) {
391 if (bitmap[idx] & 0x1) {
393 dbell_fire_entries(idx);
399 * vmci_doorbell_create() - Creates a doorbell
400 * @handle: A handle used to track the resource. Can be invalid.
401 * @flags: Flag that determines context of callback.
402 * @priv_flags: Privileges flags.
403 * @notify_cb: The callback to be ivoked when the doorbell fires.
404 * @client_data: A parameter to be passed to the callback.
406 * Creates a doorbell with the given callback. If the handle is
407 * VMCI_INVALID_HANDLE, a free handle will be assigned, if
408 * possible. The callback can be run immediately (potentially with
409 * locks held - the default) or delayed (in a kernel thread) by
410 * specifying the flag VMCI_FLAG_DELAYED_CB. If delayed execution
411 * is selected, a given callback may not be run if the kernel is
412 * unable to allocate memory for the delayed execution (highly
415 int vmci_doorbell_create(struct vmci_handle *handle,
418 vmci_callback notify_cb, void *client_data)
420 struct dbell_entry *entry;
421 struct vmci_handle new_handle;
424 if (!handle || !notify_cb || flags & ~VMCI_FLAG_DELAYED_CB ||
425 priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS)
426 return VMCI_ERROR_INVALID_ARGS;
428 entry = kmalloc(sizeof(*entry), GFP_KERNEL);
430 pr_warn("Failed allocating memory for datagram entry\n");
431 return VMCI_ERROR_NO_MEM;
434 if (vmci_handle_is_invalid(*handle)) {
435 u32 context_id = vmci_get_context_id();
437 /* Let resource code allocate a free ID for us */
438 new_handle = vmci_make_handle(context_id, VMCI_INVALID_ID);
440 bool valid_context = false;
443 * Validate the handle. We must do both of the checks below
444 * because we can be acting as both a host and a guest at the
445 * same time. We always allow the host context ID, since the
446 * host functionality is in practice always there with the
449 if (handle->context == VMCI_HOST_CONTEXT_ID ||
450 (vmci_guest_code_active() &&
451 vmci_get_context_id() == handle->context)) {
452 valid_context = true;
455 if (!valid_context || handle->resource == VMCI_INVALID_ID) {
456 pr_devel("Invalid argument (handle=0x%x:0x%x)\n",
457 handle->context, handle->resource);
458 result = VMCI_ERROR_INVALID_ARGS;
462 new_handle = *handle;
466 INIT_HLIST_NODE(&entry->node);
467 entry->priv_flags = priv_flags;
468 INIT_WORK(&entry->work, dbell_delayed_dispatch);
469 entry->run_delayed = flags & VMCI_FLAG_DELAYED_CB;
470 entry->notify_cb = notify_cb;
471 entry->client_data = client_data;
472 atomic_set(&entry->active, 0);
474 result = vmci_resource_add(&entry->resource,
475 VMCI_RESOURCE_TYPE_DOORBELL,
477 if (result != VMCI_SUCCESS) {
478 pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d\n",
479 new_handle.context, new_handle.resource, result);
483 new_handle = vmci_resource_handle(&entry->resource);
484 if (vmci_guest_code_active()) {
485 dbell_index_table_add(entry);
486 result = dbell_link(new_handle, entry->idx);
487 if (VMCI_SUCCESS != result)
488 goto destroy_resource;
490 atomic_set(&entry->active, 1);
493 *handle = new_handle;
498 dbell_index_table_remove(entry);
499 vmci_resource_remove(&entry->resource);
504 EXPORT_SYMBOL_GPL(vmci_doorbell_create);
507 * vmci_doorbell_destroy() - Destroy a doorbell.
508 * @handle: The handle tracking the resource.
510 * Destroys a doorbell previously created with vmcii_doorbell_create. This
511 * operation may block waiting for a callback to finish.
513 int vmci_doorbell_destroy(struct vmci_handle handle)
515 struct dbell_entry *entry;
516 struct vmci_resource *resource;
518 if (vmci_handle_is_invalid(handle))
519 return VMCI_ERROR_INVALID_ARGS;
521 resource = vmci_resource_by_handle(handle,
522 VMCI_RESOURCE_TYPE_DOORBELL);
524 pr_devel("Failed to destroy doorbell (handle=0x%x:0x%x)\n",
525 handle.context, handle.resource);
526 return VMCI_ERROR_NOT_FOUND;
529 entry = container_of(resource, struct dbell_entry, resource);
531 if (vmci_guest_code_active()) {
534 dbell_index_table_remove(entry);
536 result = dbell_unlink(handle);
537 if (VMCI_SUCCESS != result) {
540 * The only reason this should fail would be
541 * an inconsistency between guest and
542 * hypervisor state, where the guest believes
543 * it has an active registration whereas the
544 * hypervisor doesn't. One case where this may
545 * happen is if a doorbell is unregistered
546 * following a hibernation at a time where the
547 * doorbell state hasn't been restored on the
548 * hypervisor side yet. Since the handle has
549 * now been removed in the guest, we just
550 * print a warning and return success.
552 pr_devel("Unlink of doorbell (handle=0x%x:0x%x) unknown by hypervisor (error=%d)\n",
553 handle.context, handle.resource, result);
558 * Now remove the resource from the table. It might still be in use
559 * after this, in a callback or still on the delayed work queue.
561 vmci_resource_put(&entry->resource);
562 vmci_resource_remove(&entry->resource);
568 EXPORT_SYMBOL_GPL(vmci_doorbell_destroy);
571 * vmci_doorbell_notify() - Ring the doorbell (and hide in the bushes).
572 * @dst: The handlle identifying the doorbell resource
573 * @priv_flags: Priviledge flags.
575 * Generates a notification on the doorbell identified by the
576 * handle. For host side generation of notifications, the caller
577 * can specify what the privilege of the calling side is.
579 int vmci_doorbell_notify(struct vmci_handle dst, u32 priv_flags)
582 enum vmci_route route;
583 struct vmci_handle src;
585 if (vmci_handle_is_invalid(dst) ||
586 (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS))
587 return VMCI_ERROR_INVALID_ARGS;
589 src = VMCI_INVALID_HANDLE;
590 retval = vmci_route(&src, &dst, false, &route);
591 if (retval < VMCI_SUCCESS)
594 if (VMCI_ROUTE_AS_HOST == route)
595 return vmci_ctx_notify_dbell(VMCI_HOST_CONTEXT_ID,
598 if (VMCI_ROUTE_AS_GUEST == route)
599 return dbell_notify_as_guest(dst, priv_flags);
601 pr_warn("Unknown route (%d) for doorbell\n", route);
602 return VMCI_ERROR_DST_UNREACHABLE;
604 EXPORT_SYMBOL_GPL(vmci_doorbell_notify);