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(void); 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, size_t ram_pages); 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 * Returns a new PDS 47 */ 48 PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms, 49 const char *name); 50 51 /* 52 * Called by the bitmap code for each chunk to discard. 53 * May send a discard message, may just leave it queued to 54 * be sent later. 55 * @start,@length: a range of pages in the migration bitmap in the 56 * RAM block passed to postcopy_discard_send_init() (length=1 is one page) 57 */ 58 void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds, 59 unsigned long start, unsigned long length); 60 61 /* 62 * Called at the end of each RAMBlock by the bitmap code. 63 * Sends any outstanding discard messages, frees the PDS. 64 */ 65 void postcopy_discard_send_finish(MigrationState *ms, 66 PostcopyDiscardState *pds); 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 size_t pagesize); 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 size_t pagesize); 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 /* 107 * Allocate a page of memory that can be mapped at a later point in time 108 * using postcopy_place_page 109 * Returns: Pointer to allocated page 110 */ 111 void *postcopy_get_tmp_page(MigrationIncomingState *mis); 112 113 PostcopyState postcopy_state_get(void); 114 /* Set the state and return the old state */ 115 PostcopyState postcopy_state_set(PostcopyState new_state); 116 117 #endif 118