Merge remote-tracking branch 'remotes/bonzini-gitlab/tags/for-upstream' into staging
[qemu.git] / migration / postcopy-ram.h
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 */
17 bool 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 */
23 int postcopy_ram_incoming_setup(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 */
30 int postcopy_ram_incoming_init(MigrationIncomingState *mis);
31
32 /*
33 * At the end of a migration where postcopy_ram_incoming_init was called.
34 */
35 int 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 */
42 int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
43
44 /*
45 * Called at the start of each RAMBlock by the bitmap code.
46 */
47 void 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 */
56 void 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 */
63 void 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 */
71 int 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 */
78 int 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 */
94 typedef 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 PostcopyState postcopy_state_get(void);
104 /* Set the state and return the old state */
105 PostcopyState postcopy_state_set(PostcopyState new_state);
106
107 void postcopy_fault_thread_notify(MigrationIncomingState *mis);
108
109 /*
110 * To be called once at the start before any device initialisation
111 */
112 void postcopy_infrastructure_init(void);
113
114 /* Add a notifier to a list to be called when checking whether the devices
115 * can support postcopy.
116 * It's data is a *PostcopyNotifyData
117 * It should return 0 if OK, or a negative value on failure.
118 * On failure it must set the data->errp to an error.
119 *
120 */
121 enum PostcopyNotifyReason {
122 POSTCOPY_NOTIFY_PROBE = 0,
123 POSTCOPY_NOTIFY_INBOUND_ADVISE,
124 POSTCOPY_NOTIFY_INBOUND_LISTEN,
125 POSTCOPY_NOTIFY_INBOUND_END,
126 };
127
128 struct PostcopyNotifyData {
129 enum PostcopyNotifyReason reason;
130 Error **errp;
131 };
132
133 void postcopy_add_notifier(NotifierWithReturn *nn);
134 void postcopy_remove_notifier(NotifierWithReturn *n);
135 /* Call the notifier list set by postcopy_add_start_notifier */
136 int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp);
137
138 struct PostCopyFD;
139
140 /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
141 typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
142 /* Notification to wake, either on place or on reception of
143 * a fault on something that's already arrived (race)
144 */
145 typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset);
146
147 struct PostCopyFD {
148 int fd;
149 /* Data to pass to handler */
150 void *data;
151 /* Handler to be called whenever we get a poll event */
152 pcfdhandler handler;
153 /* Notification to wake shared client */
154 pcfdwake waker;
155 /* A string to use in error messages */
156 const char *idstr;
157 };
158
159 /* Register a userfaultfd owned by an external process for
160 * shared memory.
161 */
162 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
163 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
164 /* Call each of the shared 'waker's registerd telling them of
165 * availability of a block.
166 */
167 int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset);
168 /* postcopy_wake_shared: Notify a client ufd that a page is available
169 *
170 * Returns 0 on success
171 *
172 * @pcfd: Structure with fd, handler and name as above
173 * @client_addr: Address in the client program, not QEMU
174 * @rb: The RAMBlock the page is in
175 */
176 int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
177 RAMBlock *rb);
178 /* Callback from shared fault handlers to ask for a page */
179 int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
180 uint64_t client_addr, uint64_t offset);
181
182 #endif