qemu

postcopy-ram.h (6746B)

---

 /*
  * 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_incoming_setup(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.
  */
 void 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, unsigned long start,
                                  unsigned long length);
 
 /*
  * Called at the end of each RAMBlock by the bitmap code.
  * Sends any outstanding discard messages.
  */
 void postcopy_discard_send_finish(MigrationState *ms);
 
 /*
  * 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;
 
 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);
 
 void postcopy_thread_create(MigrationIncomingState *mis,
                             QemuThread *thread, const char *name,
                             void *(*fn)(void *), int joinable);
 
 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 registered 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);
 
 /* Hard-code channels for now for postcopy preemption */
 enum PostcopyChannels {
     RAM_CHANNEL_PRECOPY = 0,
     RAM_CHANNEL_POSTCOPY = 1,
     RAM_CHANNEL_MAX,
 };
 
 bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
 int postcopy_preempt_setup(MigrationState *s, Error **errp);
 int postcopy_preempt_wait_channel(MigrationState *s);
 
 #endif