2 * Postcopy migration for RAM
4 * Copyright 2013 Red Hat, Inc. and/or its affiliates
7 * Dave Gilbert <dgilbert@redhat.com>
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.
13 #ifndef QEMU_POSTCOPY_RAM_H
14 #define QEMU_POSTCOPY_RAM_H
16 /* Return true if the host supports everything we need to do postcopy-ram */
17 bool postcopy_ram_supported_by_host(MigrationIncomingState *mis);
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.
23 int postcopy_ram_incoming_setup(MigrationIncomingState *mis);
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
30 int postcopy_ram_incoming_init(MigrationIncomingState *mis);
33 * At the end of a migration where postcopy_ram_incoming_init was called.
35 int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis);
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
42 int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
45 * Called at the start of each RAMBlock by the bitmap code.
47 void postcopy_discard_send_init(MigrationState *ms, const char *name);
50 * Called by the bitmap code for each chunk to discard.
51 * May send a discard message, may just leave it queued to
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)
56 void postcopy_discard_send_range(MigrationState *ms, unsigned long start,
57 unsigned long length);
60 * Called at the end of each RAMBlock by the bitmap code.
61 * Sends any outstanding discard messages.
63 void postcopy_discard_send_finish(MigrationState *ms);
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
71 int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
75 * Place a zero page at (host) atomically
76 * returns 0 on success
78 int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
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
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
103 PostcopyState postcopy_state_get(void);
104 /* Set the state and return the old state */
105 PostcopyState postcopy_state_set(PostcopyState new_state);
107 void postcopy_fault_thread_notify(MigrationIncomingState *mis);
110 * To be called once at the start before any device initialisation
112 void postcopy_infrastructure_init(void);
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.
121 enum PostcopyNotifyReason {
122 POSTCOPY_NOTIFY_PROBE = 0,
123 POSTCOPY_NOTIFY_INBOUND_ADVISE,
124 POSTCOPY_NOTIFY_INBOUND_LISTEN,
125 POSTCOPY_NOTIFY_INBOUND_END,
128 struct PostcopyNotifyData {
129 enum PostcopyNotifyReason reason;
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);
138 void postcopy_thread_create(MigrationIncomingState *mis,
139 QemuThread *thread, const char *name,
140 void *(*fn)(void *), int joinable);
144 /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
145 typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
146 /* Notification to wake, either on place or on reception of
147 * a fault on something that's already arrived (race)
149 typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset);
153 /* Data to pass to handler */
155 /* Handler to be called whenever we get a poll event */
157 /* Notification to wake shared client */
159 /* A string to use in error messages */
163 /* Register a userfaultfd owned by an external process for
166 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
167 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
168 /* Call each of the shared 'waker's registered telling them of
169 * availability of a block.
171 int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset);
172 /* postcopy_wake_shared: Notify a client ufd that a page is available
174 * Returns 0 on success
176 * @pcfd: Structure with fd, handler and name as above
177 * @client_addr: Address in the client program, not QEMU
178 * @rb: The RAMBlock the page is in
180 int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
182 /* Callback from shared fault handlers to ask for a page */
183 int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
184 uint64_t client_addr, uint64_t offset);
186 /* Hard-code channels for now for postcopy preemption */
187 enum PostcopyChannels {
188 RAM_CHANNEL_PRECOPY = 0,
189 RAM_CHANNEL_POSTCOPY = 1,
193 bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
194 int postcopy_preempt_setup(MigrationState *s, Error **errp);
195 int postcopy_preempt_wait_channel(MigrationState *s);