LXR qemu/migration/postcopy-ram.h

   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 */
  17bool 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 */
  23int 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 */
  30int 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 */
  35int 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 */
  42int 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 */
  48PostcopyDiscardState *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 */
  58void 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 */
  65void 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 */
  74int 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 */
  81int 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 */
  97typedef 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 */
 111void *postcopy_get_tmp_page(MigrationIncomingState *mis);
 112
 113PostcopyState postcopy_state_get(void);
 114/* Set the state and return the old state */
 115PostcopyState postcopy_state_set(PostcopyState new_state);
 116
 117#endif
 118