diff options
Diffstat (limited to 'drivers/misc/vmw_vmci/vmci_doorbell.c')
| -rw-r--r-- | drivers/misc/vmw_vmci/vmci_doorbell.c | 601 |
1 files changed, 601 insertions, 0 deletions
diff --git a/drivers/misc/vmw_vmci/vmci_doorbell.c b/drivers/misc/vmw_vmci/vmci_doorbell.c new file mode 100644 index 00000000000..a8cee33ae8d --- /dev/null +++ b/drivers/misc/vmw_vmci/vmci_doorbell.c @@ -0,0 +1,601 @@ +/* + * VMware VMCI Driver + * + * Copyright (C) 2012 VMware, Inc. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation version 2 and no later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. + */ + +#include <linux/vmw_vmci_defs.h> +#include <linux/vmw_vmci_api.h> +#include <linux/completion.h> +#include <linux/hash.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/slab.h> + +#include "vmci_datagram.h" +#include "vmci_doorbell.h" +#include "vmci_resource.h" +#include "vmci_driver.h" +#include "vmci_route.h" + + +#define VMCI_DOORBELL_INDEX_BITS 6 +#define VMCI_DOORBELL_INDEX_TABLE_SIZE (1 << VMCI_DOORBELL_INDEX_BITS) +#define VMCI_DOORBELL_HASH(_idx) hash_32(_idx, VMCI_DOORBELL_INDEX_BITS) + +/* + * DoorbellEntry describes the a doorbell notification handle allocated by the + * host. + */ +struct dbell_entry { + struct vmci_resource resource; + struct hlist_node node; + struct work_struct work; + vmci_callback notify_cb; + void *client_data; + u32 idx; + u32 priv_flags; + bool run_delayed; + atomic_t active; /* Only used by guest personality */ +}; + +/* The VMCI index table keeps track of currently registered doorbells. */ +struct dbell_index_table { + spinlock_t lock; /* Index table lock */ + struct hlist_head entries[VMCI_DOORBELL_INDEX_TABLE_SIZE]; +}; + +static struct dbell_index_table vmci_doorbell_it = { + .lock = __SPIN_LOCK_UNLOCKED(vmci_doorbell_it.lock), +}; + +/* + * The max_notify_idx is one larger than the currently known bitmap index in + * use, and is used to determine how much of the bitmap needs to be scanned. + */ +static u32 max_notify_idx; + +/* + * The notify_idx_count is used for determining whether there are free entries + * within the bitmap (if notify_idx_count + 1 < max_notify_idx). + */ +static u32 notify_idx_count; + +/* + * The last_notify_idx_reserved is used to track the last index handed out - in + * the case where multiple handles share a notification index, we hand out + * indexes round robin based on last_notify_idx_reserved. + */ +static u32 last_notify_idx_reserved; + +/* This is a one entry cache used to by the index allocation. */ +static u32 last_notify_idx_released = PAGE_SIZE; + + +/* + * Utility function that retrieves the privilege flags associated + * with a given doorbell handle. For guest endpoints, the + * privileges are determined by the context ID, but for host + * endpoints privileges are associated with the complete + * handle. Hypervisor endpoints are not yet supported. + */ +int vmci_dbell_get_priv_flags(struct vmci_handle handle, u32 *priv_flags) +{ + if (priv_flags == NULL || handle.context == VMCI_INVALID_ID) + return VMCI_ERROR_INVALID_ARGS; + + if (handle.context == VMCI_HOST_CONTEXT_ID) { + struct dbell_entry *entry; + struct vmci_resource *resource; + + resource = vmci_resource_by_handle(handle, + VMCI_RESOURCE_TYPE_DOORBELL); + if (!resource) + return VMCI_ERROR_NOT_FOUND; + + entry = container_of(resource, struct dbell_entry, resource); + *priv_flags = entry->priv_flags; + vmci_resource_put(resource); + } else if (handle.context == VMCI_HYPERVISOR_CONTEXT_ID) { + /* + * Hypervisor endpoints for notifications are not + * supported (yet). + */ + return VMCI_ERROR_INVALID_ARGS; + } else { + *priv_flags = vmci_context_get_priv_flags(handle.context); + } + + return VMCI_SUCCESS; +} + +/* + * Find doorbell entry by bitmap index. + */ +static struct dbell_entry *dbell_index_table_find(u32 idx) +{ + u32 bucket = VMCI_DOORBELL_HASH(idx); + struct dbell_entry *dbell; + + hlist_for_each_entry(dbell, &vmci_doorbell_it.entries[bucket], + node) { + if (idx == dbell->idx) + return dbell; + } + + return NULL; +} + +/* + * Add the given entry to the index table. This willi take a reference to the + * entry's resource so that the entry is not deleted before it is removed from + * the * table. + */ +static void dbell_index_table_add(struct dbell_entry *entry) +{ + u32 bucket; + u32 new_notify_idx; + + vmci_resource_get(&entry->resource); + + spin_lock_bh(&vmci_doorbell_it.lock); + + /* + * Below we try to allocate an index in the notification + * bitmap with "not too much" sharing between resources. If we + * use less that the full bitmap, we either add to the end if + * there are no unused flags within the currently used area, + * or we search for unused ones. If we use the full bitmap, we + * allocate the index round robin. + */ + if (max_notify_idx < PAGE_SIZE || notify_idx_count < PAGE_SIZE) { + if (last_notify_idx_released < max_notify_idx && + !dbell_index_table_find(last_notify_idx_released)) { + new_notify_idx = last_notify_idx_released; + last_notify_idx_released = PAGE_SIZE; + } else { + bool reused = false; + new_notify_idx = last_notify_idx_reserved; + if (notify_idx_count + 1 < max_notify_idx) { + do { + if (!dbell_index_table_find + (new_notify_idx)) { + reused = true; + break; + } + new_notify_idx = (new_notify_idx + 1) % + max_notify_idx; + } while (new_notify_idx != + last_notify_idx_released); + } + if (!reused) { + new_notify_idx = max_notify_idx; + max_notify_idx++; + } + } + } else { + new_notify_idx = (last_notify_idx_reserved + 1) % PAGE_SIZE; + } + + last_notify_idx_reserved = new_notify_idx; + notify_idx_count++; + + entry->idx = new_notify_idx; + bucket = VMCI_DOORBELL_HASH(entry->idx); + hlist_add_head(&entry->node, &vmci_doorbell_it.entries[bucket]); + + spin_unlock_bh(&vmci_doorbell_it.lock); +} + +/* + * Remove the given entry from the index table. This will release() the + * entry's resource. + */ +static void dbell_index_table_remove(struct dbell_entry *entry) +{ + spin_lock_bh(&vmci_doorbell_it.lock); + + hlist_del_init(&entry->node); + + notify_idx_count--; + if (entry->idx == max_notify_idx - 1) { + /* + * If we delete an entry with the maximum known + * notification index, we take the opportunity to + * prune the current max. As there might be other + * unused indices immediately below, we lower the + * maximum until we hit an index in use. + */ + while (max_notify_idx > 0 && + !dbell_index_table_find(max_notify_idx - 1)) + max_notify_idx--; + } + + last_notify_idx_released = entry->idx; + + spin_unlock_bh(&vmci_doorbell_it.lock); + + vmci_resource_put(&entry->resource); +} + +/* + * Creates a link between the given doorbell handle and the given + * index in the bitmap in the device backend. A notification state + * is created in hypervisor. + */ +static int dbell_link(struct vmci_handle handle, u32 notify_idx) +{ + struct vmci_doorbell_link_msg link_msg; + + link_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID, + VMCI_DOORBELL_LINK); + link_msg.hdr.src = VMCI_ANON_SRC_HANDLE; + link_msg.hdr.payload_size = sizeof(link_msg) - VMCI_DG_HEADERSIZE; + link_msg.handle = handle; + link_msg.notify_idx = notify_idx; + + return vmci_send_datagram(&link_msg.hdr); +} + +/* + * Unlinks the given doorbell handle from an index in the bitmap in + * the device backend. The notification state is destroyed in hypervisor. + */ +static int dbell_unlink(struct vmci_handle handle) +{ + struct vmci_doorbell_unlink_msg unlink_msg; + + unlink_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID, + VMCI_DOORBELL_UNLINK); + unlink_msg.hdr.src = VMCI_ANON_SRC_HANDLE; + unlink_msg.hdr.payload_size = sizeof(unlink_msg) - VMCI_DG_HEADERSIZE; + unlink_msg.handle = handle; + + return vmci_send_datagram(&unlink_msg.hdr); +} + +/* + * Notify another guest or the host. We send a datagram down to the + * host via the hypervisor with the notification info. + */ +static int dbell_notify_as_guest(struct vmci_handle handle, u32 priv_flags) +{ + struct vmci_doorbell_notify_msg notify_msg; + + notify_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID, + VMCI_DOORBELL_NOTIFY); + notify_msg.hdr.src = VMCI_ANON_SRC_HANDLE; + notify_msg.hdr.payload_size = sizeof(notify_msg) - VMCI_DG_HEADERSIZE; + notify_msg.handle = handle; + + return vmci_send_datagram(¬ify_msg.hdr); +} + +/* + * Calls the specified callback in a delayed context. + */ +static void dbell_delayed_dispatch(struct work_struct *work) +{ + struct dbell_entry *entry = container_of(work, + struct dbell_entry, work); + + entry->notify_cb(entry->client_data); + vmci_resource_put(&entry->resource); +} + +/* + * Dispatches a doorbell notification to the host context. + */ +int vmci_dbell_host_context_notify(u32 src_cid, struct vmci_handle handle) +{ + struct dbell_entry *entry; + struct vmci_resource *resource; + + if (vmci_handle_is_invalid(handle)) { + pr_devel("Notifying an invalid doorbell (handle=0x%x:0x%x)\n", + handle.context, handle.resource); + return VMCI_ERROR_INVALID_ARGS; + } + + resource = vmci_resource_by_handle(handle, + VMCI_RESOURCE_TYPE_DOORBELL); + if (!resource) { + pr_devel("Notifying an unknown doorbell (handle=0x%x:0x%x)\n", + handle.context, handle.resource); + return VMCI_ERROR_NOT_FOUND; + } + + entry = container_of(resource, struct dbell_entry, resource); + if (entry->run_delayed) { + schedule_work(&entry->work); + } else { + entry->notify_cb(entry->client_data); + vmci_resource_put(resource); + } + + return VMCI_SUCCESS; +} + +/* + * Register the notification bitmap with the host. + */ +bool vmci_dbell_register_notification_bitmap(u32 bitmap_ppn) +{ + int result; + struct vmci_notify_bm_set_msg bitmap_set_msg; + + bitmap_set_msg.hdr.dst = vmci_make_handle(VMCI_HYPERVISOR_CONTEXT_ID, + VMCI_SET_NOTIFY_BITMAP); + bitmap_set_msg.hdr.src = VMCI_ANON_SRC_HANDLE; + bitmap_set_msg.hdr.payload_size = sizeof(bitmap_set_msg) - + VMCI_DG_HEADERSIZE; + bitmap_set_msg.bitmap_ppn = bitmap_ppn; + + result = vmci_send_datagram(&bitmap_set_msg.hdr); + if (result != VMCI_SUCCESS) { + pr_devel("Failed to register (PPN=%u) as notification bitmap (error=%d)\n", + bitmap_ppn, result); + return false; + } + return true; +} + +/* + * Executes or schedules the handlers for a given notify index. + */ +static void dbell_fire_entries(u32 notify_idx) +{ + u32 bucket = VMCI_DOORBELL_HASH(notify_idx); + struct dbell_entry *dbell; + + spin_lock_bh(&vmci_doorbell_it.lock); + + hlist_for_each_entry(dbell, &vmci_doorbell_it.entries[bucket], node) { + if (dbell->idx == notify_idx && + atomic_read(&dbell->active) == 1) { + if (dbell->run_delayed) { + vmci_resource_get(&dbell->resource); + schedule_work(&dbell->work); + } else { + dbell->notify_cb(dbell->client_data); + } + } + } + + spin_unlock_bh(&vmci_doorbell_it.lock); +} + +/* + * Scans the notification bitmap, collects pending notifications, + * resets the bitmap and invokes appropriate callbacks. + */ +void vmci_dbell_scan_notification_entries(u8 *bitmap) +{ + u32 idx; + + for (idx = 0; idx < max_notify_idx; idx++) { + if (bitmap[idx] & 0x1) { + bitmap[idx] &= ~1; + dbell_fire_entries(idx); + } + } +} + +/* + * vmci_doorbell_create() - Creates a doorbell + * @handle: A handle used to track the resource. Can be invalid. + * @flags: Flag that determines context of callback. + * @priv_flags: Privileges flags. + * @notify_cb: The callback to be ivoked when the doorbell fires. + * @client_data: A parameter to be passed to the callback. + * + * Creates a doorbell with the given callback. If the handle is + * VMCI_INVALID_HANDLE, a free handle will be assigned, if + * possible. The callback can be run immediately (potentially with + * locks held - the default) or delayed (in a kernel thread) by + * specifying the flag VMCI_FLAG_DELAYED_CB. If delayed execution + * is selected, a given callback may not be run if the kernel is + * unable to allocate memory for the delayed execution (highly + * unlikely). + */ +int vmci_doorbell_create(struct vmci_handle *handle, + u32 flags, + u32 priv_flags, + vmci_callback notify_cb, void *client_data) +{ + struct dbell_entry *entry; + struct vmci_handle new_handle; + int result; + + if (!handle || !notify_cb || flags & ~VMCI_FLAG_DELAYED_CB || + priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS) + return VMCI_ERROR_INVALID_ARGS; + + entry = kmalloc(sizeof(*entry), GFP_KERNEL); + if (entry == NULL) { + pr_warn("Failed allocating memory for datagram entry\n"); + return VMCI_ERROR_NO_MEM; + } + + if (vmci_handle_is_invalid(*handle)) { + u32 context_id = vmci_get_context_id(); + + /* Let resource code allocate a free ID for us */ + new_handle = vmci_make_handle(context_id, VMCI_INVALID_ID); + } else { + bool valid_context = false; + + /* + * Validate the handle. We must do both of the checks below + * because we can be acting as both a host and a guest at the + * same time. We always allow the host context ID, since the + * host functionality is in practice always there with the + * unified driver. + */ + if (handle->context == VMCI_HOST_CONTEXT_ID || + (vmci_guest_code_active() && + vmci_get_context_id() == handle->context)) { + valid_context = true; + } + + if (!valid_context || handle->resource == VMCI_INVALID_ID) { + pr_devel("Invalid argument (handle=0x%x:0x%x)\n", + handle->context, handle->resource); + result = VMCI_ERROR_INVALID_ARGS; + goto free_mem; + } + + new_handle = *handle; + } + + entry->idx = 0; + INIT_HLIST_NODE(&entry->node); + entry->priv_flags = priv_flags; + INIT_WORK(&entry->work, dbell_delayed_dispatch); + entry->run_delayed = flags & VMCI_FLAG_DELAYED_CB; + entry->notify_cb = notify_cb; + entry->client_data = client_data; + atomic_set(&entry->active, 0); + + result = vmci_resource_add(&entry->resource, + VMCI_RESOURCE_TYPE_DOORBELL, + new_handle); + if (result != VMCI_SUCCESS) { + pr_warn("Failed to add new resource (handle=0x%x:0x%x), error: %d\n", + new_handle.context, new_handle.resource, result); + goto free_mem; + } + + new_handle = vmci_resource_handle(&entry->resource); + if (vmci_guest_code_active()) { + dbell_index_table_add(entry); + result = dbell_link(new_handle, entry->idx); + if (VMCI_SUCCESS != result) + goto destroy_resource; + + atomic_set(&entry->active, 1); + } + + *handle = new_handle; + + return result; + + destroy_resource: + dbell_index_table_remove(entry); + vmci_resource_remove(&entry->resource); + free_mem: + kfree(entry); + return result; +} +EXPORT_SYMBOL_GPL(vmci_doorbell_create); + +/* + * vmci_doorbell_destroy() - Destroy a doorbell. + * @handle: The handle tracking the resource. + * + * Destroys a doorbell previously created with vmcii_doorbell_create. This + * operation may block waiting for a callback to finish. + */ +int vmci_doorbell_destroy(struct vmci_handle handle) +{ + struct dbell_entry *entry; + struct vmci_resource *resource; + + if (vmci_handle_is_invalid(handle)) + return VMCI_ERROR_INVALID_ARGS; + + resource = vmci_resource_by_handle(handle, + VMCI_RESOURCE_TYPE_DOORBELL); + if (!resource) { + pr_devel("Failed to destroy doorbell (handle=0x%x:0x%x)\n", + handle.context, handle.resource); + return VMCI_ERROR_NOT_FOUND; + } + + entry = container_of(resource, struct dbell_entry, resource); + + if (vmci_guest_code_active()) { + int result; + + dbell_index_table_remove(entry); + + result = dbell_unlink(handle); + if (VMCI_SUCCESS != result) { + + /* + * The only reason this should fail would be + * an inconsistency between guest and + * hypervisor state, where the guest believes + * it has an active registration whereas the + * hypervisor doesn't. One case where this may + * happen is if a doorbell is unregistered + * following a hibernation at a time where the + * doorbell state hasn't been restored on the + * hypervisor side yet. Since the handle has + * now been removed in the guest, we just + * print a warning and return success. + */ + pr_devel("Unlink of doorbell (handle=0x%x:0x%x) unknown by hypervisor (error=%d)\n", + handle.context, handle.resource, result); + } + } + + /* + * Now remove the resource from the table. It might still be in use + * after this, in a callback or still on the delayed work queue. + */ + vmci_resource_put(&entry->resource); + vmci_resource_remove(&entry->resource); + + kfree(entry); + + return VMCI_SUCCESS; +} +EXPORT_SYMBOL_GPL(vmci_doorbell_destroy); + +/* + * vmci_doorbell_notify() - Ring the doorbell (and hide in the bushes). + * @dst: The handlle identifying the doorbell resource + * @priv_flags: Priviledge flags. + * + * Generates a notification on the doorbell identified by the + * handle. For host side generation of notifications, the caller + * can specify what the privilege of the calling side is. + */ +int vmci_doorbell_notify(struct vmci_handle dst, u32 priv_flags) +{ + int retval; + enum vmci_route route; + struct vmci_handle src; + + if (vmci_handle_is_invalid(dst) || + (priv_flags & ~VMCI_PRIVILEGE_ALL_FLAGS)) + return VMCI_ERROR_INVALID_ARGS; + + src = VMCI_INVALID_HANDLE; + retval = vmci_route(&src, &dst, false, &route); + if (retval < VMCI_SUCCESS) + return retval; + + if (VMCI_ROUTE_AS_HOST == route) + return vmci_ctx_notify_dbell(VMCI_HOST_CONTEXT_ID, + dst, priv_flags); + + if (VMCI_ROUTE_AS_GUEST == route) + return dbell_notify_as_guest(dst, priv_flags); + + pr_warn("Unknown route (%d) for doorbell\n", route); + return VMCI_ERROR_DST_UNREACHABLE; +} +EXPORT_SYMBOL_GPL(vmci_doorbell_notify); |