VMCI: doorbell implementation.

VMCI doorbell code allows for notifcations between host and guest.

Signed-off-by: George Zhang <georgezhang@vmware.com>
Acked-by: Andy king <acking@vmware.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
George Zhang 2013-01-08 15:53:51 -08:00 committed by Greg Kroah-Hartman
parent a110b7ebb9
commit 83e2ec765b
2 changed files with 655 additions and 0 deletions

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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;
struct hlist_node *node;
hlist_for_each_entry(dbell, node, &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(&notify_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;
struct hlist_node *node;
spin_lock_bh(&vmci_doorbell_it.lock);
hlist_for_each_entry(dbell, node,
&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);

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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.
*/
#ifndef VMCI_DOORBELL_H
#define VMCI_DOORBELL_H
#include <linux/vmw_vmci_defs.h>
#include <linux/types.h>
#include "vmci_driver.h"
/*
* VMCINotifyResourceInfo: Used to create and destroy doorbells, and
* generate a notification for a doorbell or queue pair.
*/
struct vmci_dbell_notify_resource_info {
struct vmci_handle handle;
u16 resource;
u16 action;
s32 result;
};
/*
* Structure used for checkpointing the doorbell mappings. It is
* written to the checkpoint as is, so changing this structure will
* break checkpoint compatibility.
*/
struct dbell_cpt_state {
struct vmci_handle handle;
u64 bitmap_idx;
};
int vmci_dbell_host_context_notify(u32 src_cid, struct vmci_handle handle);
int vmci_dbell_get_priv_flags(struct vmci_handle handle, u32 *priv_flags);
bool vmci_dbell_register_notification_bitmap(u32 bitmap_ppn);
void vmci_dbell_scan_notification_entries(u8 *bitmap);
#endif /* VMCI_DOORBELL_H */