c2d5c4a7cb
Implement the outgoing migration side for the 'mapped-ram' capability.
A bitmap is introduced to track which pages have been written in the
migration file. Pages are written at a fixed location for every
ramblock. Zero pages are ignored as they'd be zero in the destination
migration as well.
The migration stream is altered to put the dirty pages for a ramblock
after its header instead of having a sequential stream of pages that
follow the ramblock headers.
Without mapped-ram (current): With mapped-ram (new):
--------------------- --------------------------------
| ramblock 1 header | | ramblock 1 header |
--------------------- --------------------------------
| ramblock 2 header | | ramblock 1 mapped-ram header |
--------------------- --------------------------------
| ... | | padding to next 1MB boundary |
--------------------- | ... |
| ramblock n header | --------------------------------
--------------------- | ramblock 1 pages |
| RAM_SAVE_FLAG_EOS | | ... |
--------------------- --------------------------------
| stream of pages | | ramblock 2 header |
| (iter 1) | --------------------------------
| ... | | ramblock 2 mapped-ram header |
--------------------- --------------------------------
| RAM_SAVE_FLAG_EOS | | padding to next 1MB boundary |
--------------------- | ... |
| stream of pages | --------------------------------
| (iter 2) | | ramblock 2 pages |
| ... | | ... |
--------------------- --------------------------------
| ... | | ... |
--------------------- --------------------------------
| RAM_SAVE_FLAG_EOS |
--------------------------------
| ... |
--------------------------------
where:
- ramblock header: the generic information for a ramblock, such as
idstr, used_len, etc.
- ramblock mapped-ram header: the new information added by this
feature: bitmap of pages written, bitmap size and offset of pages
in the migration file.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-10-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
94 lines
3.0 KiB
C
94 lines
3.0 KiB
C
/*
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* Declarations for cpu physical memory functions
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*
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* Copyright 2011 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Avi Kivity <avi@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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*
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*/
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/*
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* This header is for use by exec.c and memory.c ONLY. Do not include it.
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* The functions declared here will be removed soon.
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*/
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#ifndef QEMU_EXEC_RAMBLOCK_H
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#define QEMU_EXEC_RAMBLOCK_H
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#ifndef CONFIG_USER_ONLY
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#include "cpu-common.h"
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#include "qemu/rcu.h"
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#include "exec/ramlist.h"
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struct RAMBlock {
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struct rcu_head rcu;
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struct MemoryRegion *mr;
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uint8_t *host;
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uint8_t *colo_cache; /* For colo, VM's ram cache */
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ram_addr_t offset;
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ram_addr_t used_length;
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ram_addr_t max_length;
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void (*resized)(const char*, uint64_t length, void *host);
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uint32_t flags;
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/* Protected by the BQL. */
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char idstr[256];
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/* RCU-enabled, writes protected by the ramlist lock */
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QLIST_ENTRY(RAMBlock) next;
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QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
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int fd;
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uint64_t fd_offset;
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size_t page_size;
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/* dirty bitmap used during migration */
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unsigned long *bmap;
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/*
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* Below fields are only used by mapped-ram migration
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*/
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/* bitmap of pages present in the migration file */
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unsigned long *file_bmap;
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/*
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* offset in the file pages belonging to this ramblock are saved,
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* used only during migration to a file.
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*/
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off_t bitmap_offset;
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uint64_t pages_offset;
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/* bitmap of already received pages in postcopy */
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unsigned long *receivedmap;
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/*
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* bitmap to track already cleared dirty bitmap. When the bit is
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* set, it means the corresponding memory chunk needs a log-clear.
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* Set this up to non-NULL to enable the capability to postpone
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* and split clearing of dirty bitmap on the remote node (e.g.,
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* KVM). The bitmap will be set only when doing global sync.
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*
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* It is only used during src side of ram migration, and it is
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* protected by the global ram_state.bitmap_mutex.
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*
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* NOTE: this bitmap is different comparing to the other bitmaps
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* in that one bit can represent multiple guest pages (which is
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* decided by the `clear_bmap_shift' variable below). On
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* destination side, this should always be NULL, and the variable
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* `clear_bmap_shift' is meaningless.
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*/
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unsigned long *clear_bmap;
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uint8_t clear_bmap_shift;
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/*
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* RAM block length that corresponds to the used_length on the migration
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* source (after RAM block sizes were synchronized). Especially, after
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* starting to run the guest, used_length and postcopy_length can differ.
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* Used to register/unregister uffd handlers and as the size of the received
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* bitmap. Receiving any page beyond this length will bail out, as it
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* could not have been valid on the source.
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*/
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ram_addr_t postcopy_length;
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};
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#endif
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#endif
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