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/*
* 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.
|