193 lines
6.4 KiB
C
193 lines
6.4 KiB
C
/*
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* Postcopy migration for RAM
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*
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* Copyright 2013 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Dave Gilbert <dgilbert@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#ifndef QEMU_POSTCOPY_RAM_H
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#define QEMU_POSTCOPY_RAM_H
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/* Return true if the host supports everything we need to do postcopy-ram */
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bool postcopy_ram_supported_by_host(MigrationIncomingState *mis);
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/*
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* Make all of RAM sensitive to accesses to areas that haven't yet been written
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* and wire up anything necessary to deal with it.
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*/
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int postcopy_ram_enable_notify(MigrationIncomingState *mis);
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/*
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* Initialise postcopy-ram, setting the RAM to a state where we can go into
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* postcopy later; must be called prior to any precopy.
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* called from ram.c's similarly named ram_postcopy_incoming_init
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*/
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int postcopy_ram_incoming_init(MigrationIncomingState *mis);
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/*
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* At the end of a migration where postcopy_ram_incoming_init was called.
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*/
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int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis);
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/*
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* Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
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* however leaving it until after precopy means that most of the precopy
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* data is still THPd
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*/
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int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
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/*
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* Called at the start of each RAMBlock by the bitmap code.
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* Returns a new PDS
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*/
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PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
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const char *name);
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/*
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* Called by the bitmap code for each chunk to discard.
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* May send a discard message, may just leave it queued to
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* be sent later.
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* @start,@length: a range of pages in the migration bitmap in the
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* RAM block passed to postcopy_discard_send_init() (length=1 is one page)
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*/
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void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds,
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unsigned long start, unsigned long length);
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/*
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* Called at the end of each RAMBlock by the bitmap code.
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* Sends any outstanding discard messages, frees the PDS.
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*/
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void postcopy_discard_send_finish(MigrationState *ms,
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PostcopyDiscardState *pds);
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/*
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* Place a page (from) at (host) efficiently
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* There are restrictions on how 'from' must be mapped, in general best
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* to use other postcopy_ routines to allocate.
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* returns 0 on success
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*/
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int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
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RAMBlock *rb);
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/*
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* Place a zero page at (host) atomically
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* returns 0 on success
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*/
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int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
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RAMBlock *rb);
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/* The current postcopy state is read/set by postcopy_state_get/set
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* which update it atomically.
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* The state is updated as postcopy messages are received, and
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* in general only one thread should be writing to the state at any one
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* time, initially the main thread and then the listen thread;
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* Corner cases are where either thread finishes early and/or errors.
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* The state is checked as messages are received to ensure that
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* the source is sending us messages in the correct order.
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* The state is also used by the RAM reception code to know if it
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* has to place pages atomically, and the cleanup code at the end of
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* the main thread to know if it has to delay cleanup until the end
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* of postcopy.
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*/
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typedef enum {
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POSTCOPY_INCOMING_NONE = 0, /* Initial state - no postcopy */
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POSTCOPY_INCOMING_ADVISE,
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POSTCOPY_INCOMING_DISCARD,
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POSTCOPY_INCOMING_LISTENING,
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POSTCOPY_INCOMING_RUNNING,
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POSTCOPY_INCOMING_END
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} PostcopyState;
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/*
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* Allocate a page of memory that can be mapped at a later point in time
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* using postcopy_place_page
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* Returns: Pointer to allocated page
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*/
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void *postcopy_get_tmp_page(MigrationIncomingState *mis);
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PostcopyState postcopy_state_get(void);
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/* Set the state and return the old state */
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PostcopyState postcopy_state_set(PostcopyState new_state);
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void postcopy_fault_thread_notify(MigrationIncomingState *mis);
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/*
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* To be called once at the start before any device initialisation
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*/
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void postcopy_infrastructure_init(void);
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/* Add a notifier to a list to be called when checking whether the devices
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* can support postcopy.
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* It's data is a *PostcopyNotifyData
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* It should return 0 if OK, or a negative value on failure.
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* On failure it must set the data->errp to an error.
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*
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*/
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enum PostcopyNotifyReason {
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POSTCOPY_NOTIFY_PROBE = 0,
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POSTCOPY_NOTIFY_INBOUND_ADVISE,
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POSTCOPY_NOTIFY_INBOUND_LISTEN,
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POSTCOPY_NOTIFY_INBOUND_END,
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};
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struct PostcopyNotifyData {
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enum PostcopyNotifyReason reason;
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Error **errp;
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};
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void postcopy_add_notifier(NotifierWithReturn *nn);
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void postcopy_remove_notifier(NotifierWithReturn *n);
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/* Call the notifier list set by postcopy_add_start_notifier */
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int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp);
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struct PostCopyFD;
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/* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
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typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
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/* Notification to wake, either on place or on reception of
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* a fault on something that's already arrived (race)
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*/
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typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset);
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struct PostCopyFD {
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int fd;
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/* Data to pass to handler */
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void *data;
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/* Handler to be called whenever we get a poll event */
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pcfdhandler handler;
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/* Notification to wake shared client */
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pcfdwake waker;
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/* A string to use in error messages */
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const char *idstr;
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};
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/* Register a userfaultfd owned by an external process for
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* shared memory.
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*/
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void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
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void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
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/* Call each of the shared 'waker's registerd telling them of
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* availability of a block.
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*/
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int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset);
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/* postcopy_wake_shared: Notify a client ufd that a page is available
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*
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* Returns 0 on success
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*
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* @pcfd: Structure with fd, handler and name as above
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* @client_addr: Address in the client program, not QEMU
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* @rb: The RAMBlock the page is in
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*/
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int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
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RAMBlock *rb);
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/* Callback from shared fault handlers to ask for a page */
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int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
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uint64_t client_addr, uint64_t offset);
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#endif
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