include/exec/ramblock.h

   1 /*
   2  * Declarations for cpu physical memory functions
   3  *
   4  * Copyright 2011 Red Hat, Inc. and/or its affiliates
   5  *
   6  * Authors:
   7  *  Avi Kivity <avi@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or
  10  * later.  See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 /*
  15  * This header is for use by exec.c and memory.c ONLY.  Do not include it.
  16  * The functions declared here will be removed soon.
  17  */
  18
  19 #ifndef QEMU_EXEC_RAMBLOCK_H
  20 #define QEMU_EXEC_RAMBLOCK_H
  21
  22 #ifndef CONFIG_USER_ONLY
  23 #include "cpu-common.h"
  24 #include "qemu/rcu.h"
  25 #include "exec/ramlist.h"
  26
  27 struct RAMBlock {
  28     struct rcu_head rcu;
  29     struct MemoryRegion *mr;
  30     uint8_t *host;
  31     uint8_t *colo_cache; /* For colo, VM's ram cache */
  32     ram_addr_t offset;
  33     ram_addr_t used_length;
  34     ram_addr_t max_length;
  35     void (*resized)(const char*, uint64_t length, void *host);
  36     uint32_t flags;
  37     /* Protected by the BQL.  */
  38     char idstr[256];
  39     /* RCU-enabled, writes protected by the ramlist lock */
  40     QLIST_ENTRY(RAMBlock) next;
  41     QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
  42     int fd;
  43     uint64_t fd_offset;
  44     int guest_memfd;
  45     size_t page_size;
  46     /* dirty bitmap used during migration */
  47     unsigned long *bmap;
  48
  49     /*
  50      * Below fields are only used by mapped-ram migration
  51      */
  52     /* bitmap of pages present in the migration file */
  53     unsigned long *file_bmap;
  54     /*
  55      * offset in the file pages belonging to this ramblock are saved,
  56      * used only during migration to a file.
  57      */
  58     off_t bitmap_offset;
  59     uint64_t pages_offset;
  60
  61     /* Bitmap of already received pages.  Only used on destination side. */
  62     unsigned long *receivedmap;
  63
  64     /*
  65      * bitmap to track already cleared dirty bitmap.  When the bit is
  66      * set, it means the corresponding memory chunk needs a log-clear.
  67      * Set this up to non-NULL to enable the capability to postpone
  68      * and split clearing of dirty bitmap on the remote node (e.g.,
  69      * KVM).  The bitmap will be set only when doing global sync.
  70      *
  71      * It is only used during src side of ram migration, and it is
  72      * protected by the global ram_state.bitmap_mutex.
  73      *
  74      * NOTE: this bitmap is different comparing to the other bitmaps
  75      * in that one bit can represent multiple guest pages (which is
  76      * decided by the `clear_bmap_shift' variable below).  On
  77      * destination side, this should always be NULL, and the variable
  78      * `clear_bmap_shift' is meaningless.
  79      */
  80     unsigned long *clear_bmap;
  81     uint8_t clear_bmap_shift;
  82
  83     /*
  84      * RAM block length that corresponds to the used_length on the migration
  85      * source (after RAM block sizes were synchronized). Especially, after
  86      * starting to run the guest, used_length and postcopy_length can differ.
  87      * Used to register/unregister uffd handlers and as the size of the received
  88      * bitmap. Receiving any page beyond this length will bail out, as it
  89      * could not have been valid on the source.
  90      */
  91     ram_addr_t postcopy_length;
  92 };
  93 #endif
  94 #endif