migration/postcopy-ram.h

   1 /*
   2  * Postcopy migration for RAM
   3  *
   4  * Copyright 2013 Red Hat, Inc. and/or its affiliates
   5  *
   6  * Authors:
   7  *  Dave Gilbert  <dgilbert@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13 #ifndef QEMU_POSTCOPY_RAM_H
  14 #define QEMU_POSTCOPY_RAM_H
  15
  16 #include "qapi/qapi-types-migration.h"
  17
  18 /* Return true if the host supports everything we need to do postcopy-ram */
  19 bool postcopy_ram_supported_by_host(MigrationIncomingState *mis,
  20                                     Error **errp);
  21
  22 /*
  23  * Make all of RAM sensitive to accesses to areas that haven't yet been written
  24  * and wire up anything necessary to deal with it.
  25  */
  26 int postcopy_ram_incoming_setup(MigrationIncomingState *mis);
  27
  28 /*
  29  * Initialise postcopy-ram, setting the RAM to a state where we can go into
  30  * postcopy later; must be called prior to any precopy.
  31  * called from ram.c's similarly named ram_postcopy_incoming_init
  32  */
  33 int postcopy_ram_incoming_init(MigrationIncomingState *mis);
  34
  35 /*
  36  * At the end of a migration where postcopy_ram_incoming_init was called.
  37  */
  38 int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis);
  39
  40 /*
  41  * Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
  42  * however leaving it until after precopy means that most of the precopy
  43  * data is still THPd
  44  */
  45 int postcopy_ram_prepare_discard(MigrationIncomingState *mis);
  46
  47 /*
  48  * Called at the start of each RAMBlock by the bitmap code.
  49  */
  50 void postcopy_discard_send_init(MigrationState *ms, const char *name);
  51
  52 /*
  53  * Called by the bitmap code for each chunk to discard.
  54  * May send a discard message, may just leave it queued to
  55  * be sent later.
  56  * @start,@length: a range of pages in the migration bitmap in the
  57  *  RAM block passed to postcopy_discard_send_init() (length=1 is one page)
  58  */
  59 void postcopy_discard_send_range(MigrationState *ms, unsigned long start,
  60                                  unsigned long length);
  61
  62 /*
  63  * Called at the end of each RAMBlock by the bitmap code.
  64  * Sends any outstanding discard messages.
  65  */
  66 void postcopy_discard_send_finish(MigrationState *ms);
  67
  68 /*
  69  * Place a page (from) at (host) efficiently
  70  *    There are restrictions on how 'from' must be mapped, in general best
  71  *    to use other postcopy_ routines to allocate.
  72  * returns 0 on success
  73  */
  74 int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
  75                         RAMBlock *rb);
  76
  77 /*
  78  * Place a zero page at (host) atomically
  79  * returns 0 on success
  80  */
  81 int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
  82                              RAMBlock *rb);
  83
  84 /* The current postcopy state is read/set by postcopy_state_get/set
  85  * which update it atomically.
  86  * The state is updated as postcopy messages are received, and
  87  * in general only one thread should be writing to the state at any one
  88  * time, initially the main thread and then the listen thread;
  89  * Corner cases are where either thread finishes early and/or errors.
  90  * The state is checked as messages are received to ensure that
  91  * the source is sending us messages in the correct order.
  92  * The state is also used by the RAM reception code to know if it
  93  * has to place pages atomically, and the cleanup code at the end of
  94  * the main thread to know if it has to delay cleanup until the end
  95  * of postcopy.
  96  */
  97 typedef enum {
  98     POSTCOPY_INCOMING_NONE = 0,  /* Initial state - no postcopy */
  99     POSTCOPY_INCOMING_ADVISE,
 100     POSTCOPY_INCOMING_DISCARD,
 101     POSTCOPY_INCOMING_LISTENING,
 102     POSTCOPY_INCOMING_RUNNING,
 103     POSTCOPY_INCOMING_END
 104 } PostcopyState;
 105
 106 PostcopyState postcopy_state_get(void);
 107 /* Set the state and return the old state */
 108 PostcopyState postcopy_state_set(PostcopyState new_state);
 109
 110 void postcopy_fault_thread_notify(MigrationIncomingState *mis);
 111
 112 /*
 113  * To be called once at the start before any device initialisation
 114  */
 115 void postcopy_infrastructure_init(void);
 116
 117 /* Add a notifier to a list to be called when checking whether the devices
 118  * can support postcopy.
 119  * It's data is a *PostcopyNotifyData
 120  * It should return 0 if OK, or a negative value on failure.
 121  * On failure it must set the data->errp to an error.
 122  *
 123  */
 124 enum PostcopyNotifyReason {
 125     POSTCOPY_NOTIFY_PROBE = 0,
 126     POSTCOPY_NOTIFY_INBOUND_ADVISE,
 127     POSTCOPY_NOTIFY_INBOUND_LISTEN,
 128     POSTCOPY_NOTIFY_INBOUND_END,
 129 };
 130
 131 struct PostcopyNotifyData {
 132     enum PostcopyNotifyReason reason;
 133 };
 134
 135 void postcopy_add_notifier(NotifierWithReturn *nn);
 136 void postcopy_remove_notifier(NotifierWithReturn *n);
 137 /* Call the notifier list set by postcopy_add_start_notifier */
 138 int postcopy_notify(enum PostcopyNotifyReason reason, Error **errp);
 139
 140 void postcopy_thread_create(MigrationIncomingState *mis,
 141                             QemuThread *thread, const char *name,
 142                             void *(*fn)(void *), int joinable);
 143
 144 struct PostCopyFD;
 145
 146 /* ufd is a pointer to the struct uffd_msg *TODO: more Portable! */
 147 typedef int (*pcfdhandler)(struct PostCopyFD *pcfd, void *ufd);
 148 /* Notification to wake, either on place or on reception of
 149  * a fault on something that's already arrived (race)
 150  */
 151 typedef int (*pcfdwake)(struct PostCopyFD *pcfd, RAMBlock *rb, uint64_t offset);
 152
 153 struct PostCopyFD {
 154     int fd;
 155     /* Data to pass to handler */
 156     void *data;
 157     /* Handler to be called whenever we get a poll event */
 158     pcfdhandler handler;
 159     /* Notification to wake shared client */
 160     pcfdwake waker;
 161     /* A string to use in error messages */
 162     const char *idstr;
 163 };
 164
 165 /* Register a userfaultfd owned by an external process for
 166  * shared memory.
 167  */
 168 void postcopy_register_shared_ufd(struct PostCopyFD *pcfd);
 169 void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd);
 170 /* Call each of the shared 'waker's registered telling them of
 171  * availability of a block.
 172  */
 173 int postcopy_notify_shared_wake(RAMBlock *rb, uint64_t offset);
 174 /* postcopy_wake_shared: Notify a client ufd that a page is available
 175  *
 176  * Returns 0 on success
 177  *
 178  * @pcfd: Structure with fd, handler and name as above
 179  * @client_addr: Address in the client program, not QEMU
 180  * @rb: The RAMBlock the page is in
 181  */
 182 int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
 183                          RAMBlock *rb);
 184 /* Callback from shared fault handlers to ask for a page */
 185 int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
 186                                  uint64_t client_addr, uint64_t offset);
 187
 188 /* Hard-code channels for now for postcopy preemption */
 189 enum PostcopyChannels {
 190     RAM_CHANNEL_PRECOPY = 0,
 191     RAM_CHANNEL_POSTCOPY = 1,
 192     RAM_CHANNEL_MAX,
 193 };
 194
 195 void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
 196 void postcopy_preempt_setup(MigrationState *s);
 197 int postcopy_preempt_establish_channel(MigrationState *s);
 198 bool postcopy_is_paused(MigrationStatus status);
 199
 200 #endif