xref: /qemu/include/exec/ramblock.h (revision 2abf0da2)
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     size_t page_size;
45     /* dirty bitmap used during migration */
46     unsigned long *bmap;
47     /* bitmap of already received pages in postcopy */
48     unsigned long *receivedmap;
49 
50     /*
51      * bitmap to track already cleared dirty bitmap.  When the bit is
52      * set, it means the corresponding memory chunk needs a log-clear.
53      * Set this up to non-NULL to enable the capability to postpone
54      * and split clearing of dirty bitmap on the remote node (e.g.,
55      * KVM).  The bitmap will be set only when doing global sync.
56      *
57      * It is only used during src side of ram migration, and it is
58      * protected by the global ram_state.bitmap_mutex.
59      *
60      * NOTE: this bitmap is different comparing to the other bitmaps
61      * in that one bit can represent multiple guest pages (which is
62      * decided by the `clear_bmap_shift' variable below).  On
63      * destination side, this should always be NULL, and the variable
64      * `clear_bmap_shift' is meaningless.
65      */
66     unsigned long *clear_bmap;
67     uint8_t clear_bmap_shift;
68 
69     /*
70      * RAM block length that corresponds to the used_length on the migration
71      * source (after RAM block sizes were synchronized). Especially, after
72      * starting to run the guest, used_length and postcopy_length can differ.
73      * Used to register/unregister uffd handlers and as the size of the received
74      * bitmap. Receiving any page beyond this length will bail out, as it
75      * could not have been valid on the source.
76      */
77     ram_addr_t postcopy_length;
78 };
79 #endif
80 #endif
81