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/*
* Postcopy migration for RAM
*
* Copyright 2013 Red Hat, Inc. and/or its affiliates
*
* Authors:
* Dave Gilbert <dgilbert@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#ifndef QEMU_POSTCOPY_RAM_H
#define QEMU_POSTCOPY_RAM_H
/* Return true if the host supports everything we need to do postcopy-ram */
bool postcopy_ram_supported_by_host(void);
/*
* Make all of RAM sensitive to accesses to areas that haven't yet been written
* and wire up anything necessary to deal with it.
*/
int postcopy_ram_enable_notify(MigrationIncomingState *mis);
/*
* Initialise postcopy-ram, setting the RAM to a state where we can go into
* postcopy later; must be called prior to any precopy.
* called from ram.c's similarly named ram_postcopy_incoming_init
*/
int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages);
/*
* At the end of a migration where postcopy_ram_incoming_init was called.
*/
int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis);
/*
* Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
* however leaving it until after precopy means that most of the precopy
* data is still THPd
*/
int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
/*
* Called at the start of each RAMBlock by the bitmap code.
* Returns a new PDS
*/
PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
const char *name);
/*
* Called by the bitmap code for each chunk to discard.
* May send a discard message, may just leave it queued to
* be sent later.
* @start,@length: a range of pages in the migration bitmap in the
* RAM block passed to postcopy_discard_send_init() (length=1 is one page)
*/
void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds,
unsigned long start, unsigned long length);
/*
* Called at the end of each RAMBlock by the bitmap code.
* Sends any outstanding discard messages, frees the PDS.
*/
void postcopy_discard_send_finish(MigrationState *ms,
PostcopyDiscardState *pds);
/*
* Place a page (from) at (host) efficiently
* There are restrictions on how 'from' must be mapped, in general best
* to use other postcopy_ routines to allocate.
* returns 0 on success
*/
int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
size_t pagesize);
/*
* Place a zero page at (host) atomically
* returns 0 on success
*/
int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
size_t pagesize);
/* The current postcopy state is read/set by postcopy_state_get/set
* which update it atomically.
* The state is updated as postcopy messages are received, and
* in general only one thread should be writing to the state at any one
* time, initially the main thread and then the listen thread;
* Corner cases are where either thread finishes early and/or errors.
* The state is checked as messages are received to ensure that
* the source is sending us messages in the correct order.
* The state is also used by the RAM reception code to know if it
* has to place pages atomically, and the cleanup code at the end of
* the main thread to know if it has to delay cleanup until the end
* of postcopy.
*/
typedef enum {
POSTCOPY_INCOMING_NONE = 0, /* Initial state - no postcopy */
POSTCOPY_INCOMING_ADVISE,
POSTCOPY_INCOMING_DISCARD,
POSTCOPY_INCOMING_LISTENING,
POSTCOPY_INCOMING_RUNNING,
POSTCOPY_INCOMING_END
} PostcopyState;
/*
* Allocate a page of memory that can be mapped at a later point in time
* using postcopy_place_page
* Returns: Pointer to allocated page
*/
void *postcopy_get_tmp_page(MigrationIncomingState *mis);
PostcopyState postcopy_state_get(void);
/* Set the state and return the old state */
PostcopyState postcopy_state_set(PostcopyState new_state);
#endif
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