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