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 Error **errp); 19 20 /* 21 * Make all of RAM sensitive to accesses to areas that haven't yet been written 22 * and wire up anything necessary to deal with it. 23 */ 24 int postcopy_ram_incoming_setup(MigrationIncomingState *mis); 25 26 /* 27 * Initialise postcopy-ram, setting the RAM to a state where we can go into 28 * postcopy later; must be called prior to any precopy. 29 * called from ram.c's similarly named ram_postcopy_incoming_init 30 */ 31 int postcopy_ram_incoming_init(MigrationIncomingState *mis); 32 33 /* 34 * At the end of a migration where postcopy_ram_incoming_init was called. 35 */ 36 int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis); 37 38 /* 39 * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard 40 * however leaving it until after precopy means that most of the precopy 41 * data is still THPd 42 */ 43 int postcopy_ram_prepare_discard(MigrationIncomingState *mis); 44 45 /* 46 * Called at the start of each RAMBlock by the bitmap code. 47 */ 48 void postcopy_discard_send_init(MigrationState *ms, const char *name); 49 50 /* 51 * Called by the bitmap code for each chunk to discard. 52 * May send a discard message, may just leave it queued to 53 * be sent later. 54 * @start,@length: a range of pages in the migration bitmap in the 55 * RAM block passed to postcopy_discard_send_init() (length=1 is one page) 56 */ 57 void postcopy_discard_send_range(MigrationState *ms, unsigned long start, 58 unsigned long length); 59 60 /* 61 * Called at the end of each RAMBlock by the bitmap code. 62 * Sends any outstanding discard messages. 63 */ 64 void postcopy_discard_send_finish(MigrationState *ms); 65 66 /* 67 * Place a page (from) at (host) efficiently 68 * There are restrictions on how 'from' must be mapped, in general best 69 * to use other postcopy_ routines to allocate. 70 * returns 0 on success 71 */ 72 int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from, 73 RAMBlock *rb); 74 75 /* 76 * Place a zero page at (host) atomically 77 * returns 0 on success 78 */ 79 int postcopy_place_page_zero(MigrationIncomingState *mis, void *host, 80 RAMBlock *rb); 81 82 /* The current postcopy state is read/set by postcopy_state_get/set 83 * which update it atomically. 84 * The state is updated as postcopy messages are received, and 85 * in general only one thread should be writing to the state at any one 86 * time, initially the main thread and then the listen thread; 87 * Corner cases are where either thread finishes early and/or errors. 88 * The state is checked as messages are received to ensure that 89 * the source is sending us messages in the correct order. 90 * The state is also used by the RAM reception code to know if it 91 * has to place pages atomically, and the cleanup code at the end of 92 * the main thread to know if it has to delay cleanup until the end 93 * of postcopy. 94 */ 95 typedef enum { 96 POSTCOPY_INCOMING_NONE = 0, /* Initial state - no postcopy */ 97 POSTCOPY_INCOMING_ADVISE, 98 POSTCOPY_INCOMING_DISCARD, 99 POSTCOPY_INCOMING_LISTENING, 100 POSTCOPY_INCOMING_RUNNING, 101 POSTCOPY_INCOMING_END 102 } PostcopyState; 103 104 PostcopyState postcopy_state_get(void); 105 /* Set the state and return the old state */ 106 PostcopyState postcopy_state_set(PostcopyState new_state); 107 108 void postcopy_fault_thread_notify(MigrationIncomingState *mis); 109 110 /* 111 * To be called once at the start before any device initialisation 112 */ 113 void postcopy_infrastructure_init(void); 114 115 /* Add a notifier to a list to be called when checking whether the devices 116 * can support postcopy. 117 * It's data is a *PostcopyNotifyData 118 * It should return 0 if OK, or a negative value on failure. 119 * On failure it must set the data->errp to an error. 120 * 121 */ 122 enum PostcopyNotifyReason { 123 POSTCOPY_NOTIFY_PROBE = 0, 124 POSTCOPY_NOTIFY_INBOUND_ADVISE, 125 POSTCOPY_NOTIFY_INBOUND_LISTEN, 126 POSTCOPY_NOTIFY_INBOUND_END, 127 }; 128 129 struct PostcopyNotifyData { 130 enum PostcopyNotifyReason reason; 131 Error **errp; 132 }; 133 134 void postcopy_add_notifier(NotifierWithReturn *nn); 135 void postcopy_remove_notifier(NotifierWithReturn *n); 136 /* Call the notifier list set by postcopy_add_start_notifier */ 137 int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp); 138 139 void postcopy_thread_create(MigrationIncomingState *mis, 140 QemuThread *thread, const char *name, 141 void *(*fn)(void *), int joinable); 142 143 struct PostCopyFD; 144 145 /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */ 146 typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd); 147 /* Notification to wake, either on place or on reception of 148 * a fault on something that's already arrived (race) 149 */ 150 typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset); 151 152 struct PostCopyFD { 153 int fd; 154 /* Data to pass to handler */ 155 void *data; 156 /* Handler to be called whenever we get a poll event */ 157 pcfdhandler handler; 158 /* Notification to wake shared client */ 159 pcfdwake waker; 160 /* A string to use in error messages */ 161 const char *idstr; 162 }; 163 164 /* Register a userfaultfd owned by an external process for 165 * shared memory. 166 */ 167 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd); 168 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd); 169 /* Call each of the shared 'waker's registered telling them of 170 * availability of a block. 171 */ 172 int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset); 173 /* postcopy_wake_shared: Notify a client ufd that a page is available 174 * 175 * Returns 0 on success 176 * 177 * @pcfd: Structure with fd, handler and name as above 178 * @client_addr: Address in the client program, not QEMU 179 * @rb: The RAMBlock the page is in 180 */ 181 int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr, 182 RAMBlock *rb); 183 /* Callback from shared fault handlers to ask for a page */ 184 int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, 185 uint64_t client_addr, uint64_t offset); 186 187 /* Hard-code channels for now for postcopy preemption */ 188 enum PostcopyChannels { 189 RAM_CHANNEL_PRECOPY = 0, 190 RAM_CHANNEL_POSTCOPY = 1, 191 RAM_CHANNEL_MAX, 192 }; 193 194 void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file); 195 void postcopy_preempt_setup(MigrationState *s); 196 int postcopy_preempt_establish_channel(MigrationState *s); 197 198 #endif 199