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 #include "qapi/qapi-types-migration.h" 17 18 /* Return true if the host supports everything we need to do postcopy-ram */ 19 bool postcopy_ram_supported_by_host(MigrationIncomingState *mis, 20 Error **errp); 21 22 /* 23 * Make all of RAM sensitive to accesses to areas that haven't yet been written 24 * and wire up anything necessary to deal with it. 25 */ 26 int postcopy_ram_incoming_setup(MigrationIncomingState *mis); 27 28 /* 29 * Initialise postcopy-ram, setting the RAM to a state where we can go into 30 * postcopy later; must be called prior to any precopy. 31 * called from ram.c's similarly named ram_postcopy_incoming_init 32 */ 33 int postcopy_ram_incoming_init(MigrationIncomingState *mis); 34 35 /* 36 * At the end of a migration where postcopy_ram_incoming_init was called. 37 */ 38 int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis); 39 40 /* 41 * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard 42 * however leaving it until after precopy means that most of the precopy 43 * data is still THPd 44 */ 45 int postcopy_ram_prepare_discard(MigrationIncomingState *mis); 46 47 /* 48 * Called at the start of each RAMBlock by the bitmap code. 49 */ 50 void postcopy_discard_send_init(MigrationState *ms, const char *name); 51 52 /* 53 * Called by the bitmap code for each chunk to discard. 54 * May send a discard message, may just leave it queued to 55 * be sent later. 56 * @start,@length: a range of pages in the migration bitmap in the 57 * RAM block passed to postcopy_discard_send_init() (length=1 is one page) 58 */ 59 void postcopy_discard_send_range(MigrationState *ms, unsigned long start, 60 unsigned long length); 61 62 /* 63 * Called at the end of each RAMBlock by the bitmap code. 64 * Sends any outstanding discard messages. 65 */ 66 void postcopy_discard_send_finish(MigrationState *ms); 67 68 /* 69 * Place a page (from) at (host) efficiently 70 * There are restrictions on how 'from' must be mapped, in general best 71 * to use other postcopy_ routines to allocate. 72 * returns 0 on success 73 */ 74 int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from, 75 RAMBlock *rb); 76 77 /* 78 * Place a zero page at (host) atomically 79 * returns 0 on success 80 */ 81 int postcopy_place_page_zero(MigrationIncomingState *mis, void *host, 82 RAMBlock *rb); 83 84 /* The current postcopy state is read/set by postcopy_state_get/set 85 * which update it atomically. 86 * The state is updated as postcopy messages are received, and 87 * in general only one thread should be writing to the state at any one 88 * time, initially the main thread and then the listen thread; 89 * Corner cases are where either thread finishes early and/or errors. 90 * The state is checked as messages are received to ensure that 91 * the source is sending us messages in the correct order. 92 * The state is also used by the RAM reception code to know if it 93 * has to place pages atomically, and the cleanup code at the end of 94 * the main thread to know if it has to delay cleanup until the end 95 * of postcopy. 96 */ 97 typedef enum { 98 POSTCOPY_INCOMING_NONE = 0, /* Initial state - no postcopy */ 99 POSTCOPY_INCOMING_ADVISE, 100 POSTCOPY_INCOMING_DISCARD, 101 POSTCOPY_INCOMING_LISTENING, 102 POSTCOPY_INCOMING_RUNNING, 103 POSTCOPY_INCOMING_END 104 } PostcopyState; 105 106 PostcopyState postcopy_state_get(void); 107 /* Set the state and return the old state */ 108 PostcopyState postcopy_state_set(PostcopyState new_state); 109 110 void postcopy_fault_thread_notify(MigrationIncomingState *mis); 111 112 /* 113 * To be called once at the start before any device initialisation 114 */ 115 void postcopy_infrastructure_init(void); 116 117 /* Add a notifier to a list to be called when checking whether the devices 118 * can support postcopy. 119 * It's data is a *PostcopyNotifyData 120 * It should return 0 if OK, or a negative value on failure. 121 * On failure it must set the data->errp to an error. 122 * 123 */ 124 enum PostcopyNotifyReason { 125 POSTCOPY_NOTIFY_PROBE = 0, 126 POSTCOPY_NOTIFY_INBOUND_ADVISE, 127 POSTCOPY_NOTIFY_INBOUND_LISTEN, 128 POSTCOPY_NOTIFY_INBOUND_END, 129 }; 130 131 struct PostcopyNotifyData { 132 enum PostcopyNotifyReason reason; 133 }; 134 135 void postcopy_add_notifier(NotifierWithReturn *nn); 136 void postcopy_remove_notifier(NotifierWithReturn *n); 137 /* Call the notifier list set by postcopy_add_start_notifier */ 138 int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp); 139 140 void postcopy_thread_create(MigrationIncomingState *mis, 141 QemuThread *thread, const char *name, 142 void *(*fn)(void *), int joinable); 143 144 struct PostCopyFD; 145 146 /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */ 147 typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd); 148 /* Notification to wake, either on place or on reception of 149 * a fault on something that's already arrived (race) 150 */ 151 typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset); 152 153 struct PostCopyFD { 154 int fd; 155 /* Data to pass to handler */ 156 void *data; 157 /* Handler to be called whenever we get a poll event */ 158 pcfdhandler handler; 159 /* Notification to wake shared client */ 160 pcfdwake waker; 161 /* A string to use in error messages */ 162 const char *idstr; 163 }; 164 165 /* Register a userfaultfd owned by an external process for 166 * shared memory. 167 */ 168 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd); 169 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd); 170 /* Call each of the shared 'waker's registered telling them of 171 * availability of a block. 172 */ 173 int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset); 174 /* postcopy_wake_shared: Notify a client ufd that a page is available 175 * 176 * Returns 0 on success 177 * 178 * @pcfd: Structure with fd, handler and name as above 179 * @client_addr: Address in the client program, not QEMU 180 * @rb: The RAMBlock the page is in 181 */ 182 int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr, 183 RAMBlock *rb); 184 /* Callback from shared fault handlers to ask for a page */ 185 int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, 186 uint64_t client_addr, uint64_t offset); 187 188 /* Hard-code channels for now for postcopy preemption */ 189 enum PostcopyChannels { 190 RAM_CHANNEL_PRECOPY = 0, 191 RAM_CHANNEL_POSTCOPY = 1, 192 RAM_CHANNEL_MAX, 193 }; 194 195 void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file); 196 void postcopy_preempt_setup(MigrationState *s); 197 int postcopy_preempt_establish_channel(MigrationState *s); 198 bool postcopy_is_paused(MigrationStatus status); 199 200 #endif 201