/* * 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(MigrationIncomingState *mis); /* * 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); /* * 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, RAMBlock *rb); /* * Place a zero page at (host) atomically * returns 0 on success */ int postcopy_place_page_zero(MigrationIncomingState *mis, void *host, RAMBlock *rb); /* 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); void postcopy_fault_thread_notify(MigrationIncomingState *mis); /* * To be called once at the start before any device initialisation */ void postcopy_infrastructure_init(void); /* Add a notifier to a list to be called when checking whether the devices * can support postcopy. * It's data is a *PostcopyNotifyData * It should return 0 if OK, or a negative value on failure. * On failure it must set the data->errp to an error. * */ enum PostcopyNotifyReason { POSTCOPY_NOTIFY_PROBE = 0, POSTCOPY_NOTIFY_INBOUND_ADVISE, POSTCOPY_NOTIFY_INBOUND_LISTEN, POSTCOPY_NOTIFY_INBOUND_END, }; struct PostcopyNotifyData { enum PostcopyNotifyReason reason; Error **errp; }; void postcopy_add_notifier(NotifierWithReturn *nn); void postcopy_remove_notifier(NotifierWithReturn *n); /* Call the notifier list set by postcopy_add_start_notifier */ int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp); struct PostCopyFD; /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */ typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd); /* Notification to wake, either on place or on reception of * a fault on something that's already arrived (race) */ typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset); struct PostCopyFD { int fd; /* Data to pass to handler */ void *data; /* Handler to be called whenever we get a poll event */ pcfdhandler handler; /* Notification to wake shared client */ pcfdwake waker; /* A string to use in error messages */ const char *idstr; }; /* Register a userfaultfd owned by an external process for * shared memory. */ void postcopy_register_shared_ufd(struct PostCopyFD *pcfd); void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd); /* Call each of the shared 'waker's registerd telling them of * availability of a block. */ int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset); /* postcopy_wake_shared: Notify a client ufd that a page is available * * Returns 0 on success * * @pcfd: Structure with fd, handler and name as above * @client_addr: Address in the client program, not QEMU * @rb: The RAMBlock the page is in */ int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr, RAMBlock *rb); /* Callback from shared fault handlers to ask for a page */ int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t client_addr, uint64_t offset); #endif