LXR qemu/include/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(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 */
  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 * Discard the contents of 'length' bytes from 'start'
  39 * We can assume that if we've been called postcopy_ram_hosttest returned true
  40 */
  41int postcopy_ram_discard_range(MigrationIncomingState *mis, uint8_t *start,
  42                               size_t length);
  43
  44/*
  45 * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
  46 * however leaving it until after precopy means that most of the precopy
  47 * data is still THPd
  48 */
  49int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
  50
  51/*
  52 * Called at the start of each RAMBlock by the bitmap code.
  53 * 'offset' is the bitmap offset of the named RAMBlock in the migration
  54 * bitmap.
  55 * Returns a new PDS
  56 */
  57PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
  58                                                 unsigned long offset,
  59                                                 const char *name);
  60
  61/*
  62 * Called by the bitmap code for each chunk to discard.
  63 * May send a discard message, may just leave it queued to
  64 * be sent later.
  65 * @start,@length: a range of pages in the migration bitmap in the
  66 *  RAM block passed to postcopy_discard_send_init() (length=1 is one page)
  67 */
  68void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds,
  69                                 unsigned long start, unsigned long length);
  70
  71/*
  72 * Called at the end of each RAMBlock by the bitmap code.
  73 * Sends any outstanding discard messages, frees the PDS.
  74 */
  75void postcopy_discard_send_finish(MigrationState *ms,
  76                                  PostcopyDiscardState *pds);
  77
  78/*
  79 * Place a page (from) at (host) efficiently
  80 *    There are restrictions on how 'from' must be mapped, in general best
  81 *    to use other postcopy_ routines to allocate.
  82 * returns 0 on success
  83 */
  84int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from);
  85
  86/*
  87 * Place a zero page at (host) atomically
  88 * returns 0 on success
  89 */
  90int postcopy_place_page_zero(MigrationIncomingState *mis, void *host);
  91
  92/*
  93 * Allocate a page of memory that can be mapped at a later point in time
  94 * using postcopy_place_page
  95 * Returns: Pointer to allocated page
  96 */
  97void *postcopy_get_tmp_page(MigrationIncomingState *mis);
  98
  99#endif
 100