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_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 | */ |
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 | /* |
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 | */ |
108 | void *postcopy_get_tmp_page(MigrationIncomingState *mis); |
109 | |
110 | PostcopyState postcopy_state_get(void); |
111 | /* Set the state and return the old state */ |
112 | PostcopyState postcopy_state_set(PostcopyState new_state); |
113 | |
114 | void postcopy_fault_thread_notify(MigrationIncomingState *mis); |
115 | |
116 | /* |
117 | * To be called once at the start before any device initialisation |
118 | */ |
119 | void 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 | */ |
128 | enum PostcopyNotifyReason { |
129 | POSTCOPY_NOTIFY_PROBE = 0, |
130 | POSTCOPY_NOTIFY_INBOUND_ADVISE, |
131 | POSTCOPY_NOTIFY_INBOUND_LISTEN, |
132 | POSTCOPY_NOTIFY_INBOUND_END, |
133 | }; |
134 | |
135 | struct PostcopyNotifyData { |
136 | enum PostcopyNotifyReason reason; |
137 | Error **errp; |
138 | }; |
139 | |
140 | void postcopy_add_notifier(NotifierWithReturn *nn); |
141 | void postcopy_remove_notifier(NotifierWithReturn *n); |
142 | /* Call the notifier list set by postcopy_add_start_notifier */ |
143 | int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp); |
144 | |
145 | struct PostCopyFD; |
146 | |
147 | /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */ |
148 | typedef 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 | */ |
152 | typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset); |
153 | |
154 | struct 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 | */ |
169 | void postcopy_register_shared_ufd(struct PostCopyFD *pcfd); |
170 | void 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 | */ |
174 | int 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 | */ |
183 | int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr, |
184 | RAMBlock *rb); |
185 | /* Callback from shared fault handlers to ask for a page */ |
186 | int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, |
187 | uint64_t client_addr, uint64_t offset); |
188 | |
189 | #endif |
190 | |