1/*
2 * Postcopy migration for RAM
3 *
4 * Copyright 2013 Red Hat, Inc. and/or its affiliates
5 *
6 * Authors:
7 * Dave Gilbert <dgilbert@redhat.com>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 *
12 */
13#ifndef QEMU_POSTCOPY_RAM_H
14#define QEMU_POSTCOPY_RAM_H
15
16/* Return true if the host supports everything we need to do postcopy-ram */
17bool postcopy_ram_supported_by_host(MigrationIncomingState *mis);
18
19/*
20 * Make all of RAM sensitive to accesses to areas that haven't yet been written
21 * and wire up anything necessary to deal with it.
22 */
23int postcopy_ram_enable_notify(MigrationIncomingState *mis);
24
25/*
26 * Initialise postcopy-ram, setting the RAM to a state where we can go into
27 * postcopy later; must be called prior to any precopy.
28 * called from ram.c's similarly named ram_postcopy_incoming_init
29 */
30int postcopy_ram_incoming_init(MigrationIncomingState *mis);
31
32/*
33 * At the end of a migration where postcopy_ram_incoming_init was called.
34 */
35int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis);
36
37/*
38 * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
39 * however leaving it until after precopy means that most of the precopy
40 * data is still THPd
41 */
42int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
43
44/*
45 * Called at the start of each RAMBlock by the bitmap code.
46 */
47void postcopy_discard_send_init(MigrationState *ms, const char *name);
48
49/*
50 * Called by the bitmap code for each chunk to discard.
51 * May send a discard message, may just leave it queued to
52 * be sent later.
53 * @start,@length: a range of pages in the migration bitmap in the
54 * RAM block passed to postcopy_discard_send_init() (length=1 is one page)
55 */
56void postcopy_discard_send_range(MigrationState *ms, unsigned long start,
57 unsigned long length);
58
59/*
60 * Called at the end of each RAMBlock by the bitmap code.
61 * Sends any outstanding discard messages.
62 */
63void postcopy_discard_send_finish(MigrationState *ms);
64
65/*
66 * Place a page (from) at (host) efficiently
67 * There are restrictions on how 'from' must be mapped, in general best
68 * to use other postcopy_ routines to allocate.
69 * returns 0 on success
70 */
71int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
72 RAMBlock *rb);
73
74/*
75 * Place a zero page at (host) atomically
76 * returns 0 on success
77 */
78int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
79 RAMBlock *rb);
80
81/* The current postcopy state is read/set by postcopy_state_get/set
82 * which update it atomically.
83 * The state is updated as postcopy messages are received, and
84 * in general only one thread should be writing to the state at any one
85 * time, initially the main thread and then the listen thread;
86 * Corner cases are where either thread finishes early and/or errors.
87 * The state is checked as messages are received to ensure that
88 * the source is sending us messages in the correct order.
89 * The state is also used by the RAM reception code to know if it
90 * has to place pages atomically, and the cleanup code at the end of
91 * the main thread to know if it has to delay cleanup until the end
92 * of postcopy.
93 */
94typedef enum {
95 POSTCOPY_INCOMING_NONE = 0, /* Initial state - no postcopy */
96 POSTCOPY_INCOMING_ADVISE,
97 POSTCOPY_INCOMING_DISCARD,
98 POSTCOPY_INCOMING_LISTENING,
99 POSTCOPY_INCOMING_RUNNING,
100 POSTCOPY_INCOMING_END
101} PostcopyState;
102
103/*
104 * Allocate a page of memory that can be mapped at a later point in time
105 * using postcopy_place_page
106 * Returns: Pointer to allocated page
107 */
108void *postcopy_get_tmp_page(MigrationIncomingState *mis);
109
110PostcopyState postcopy_state_get(void);
111/* Set the state and return the old state */
112PostcopyState postcopy_state_set(PostcopyState new_state);
113
114void postcopy_fault_thread_notify(MigrationIncomingState *mis);
115
116/*
117 * To be called once at the start before any device initialisation
118 */
119void postcopy_infrastructure_init(void);
120
121/* Add a notifier to a list to be called when checking whether the devices
122 * can support postcopy.
123 * It's data is a *PostcopyNotifyData
124 * It should return 0 if OK, or a negative value on failure.
125 * On failure it must set the data->errp to an error.
126 *
127 */
128enum PostcopyNotifyReason {
129 POSTCOPY_NOTIFY_PROBE = 0,
130 POSTCOPY_NOTIFY_INBOUND_ADVISE,
131 POSTCOPY_NOTIFY_INBOUND_LISTEN,
132 POSTCOPY_NOTIFY_INBOUND_END,
133};
134
135struct PostcopyNotifyData {
136 enum PostcopyNotifyReason reason;
137 Error **errp;
138};
139
140void postcopy_add_notifier(NotifierWithReturn *nn);
141void postcopy_remove_notifier(NotifierWithReturn *n);
142/* Call the notifier list set by postcopy_add_start_notifier */
143int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp);
144
145struct PostCopyFD;
146
147/* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
148typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
149/* Notification to wake, either on place or on reception of
150 * a fault on something that's already arrived (race)
151 */
152typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset);
153
154struct PostCopyFD {
155 int fd;
156 /* Data to pass to handler */
157 void *data;
158 /* Handler to be called whenever we get a poll event */
159 pcfdhandler handler;
160 /* Notification to wake shared client */
161 pcfdwake waker;
162 /* A string to use in error messages */
163 const char *idstr;
164};
165
166/* Register a userfaultfd owned by an external process for
167 * shared memory.
168 */
169void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
170void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
171/* Call each of the shared 'waker's registerd telling them of
172 * availability of a block.
173 */
174int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset);
175/* postcopy_wake_shared: Notify a client ufd that a page is available
176 *
177 * Returns 0 on success
178 *
179 * @pcfd: Structure with fd, handler and name as above
180 * @client_addr: Address in the client program, not QEMU
181 * @rb: The RAMBlock the page is in
182 */
183int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
184 RAMBlock *rb);
185/* Callback from shared fault handlers to ask for a page */
186int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
187 uint64_t client_addr, uint64_t offset);
188
189#endif
190