migration/global_state.c

   1 /*
   2  * Global State configuration
   3  *
   4  * Copyright (c) 2014-2017 Red Hat Inc
   5  *
   6  * Authors:
   7  *  Juan Quintela <quintela@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 #include "qemu/osdep.h"
  14 #include "qemu/cutils.h"
  15 #include "qemu/error-report.h"
  16 #include "sysemu/runstate.h"
  17 #include "qapi/error.h"
  18 #include "migration.h"
  19 #include "migration/global_state.h"
  20 #include "migration/vmstate.h"
  21 #include "trace.h"
  22
  23 typedef struct {
  24     uint32_t size;
  25     uint8_t runstate[100];
  26     RunState state;
  27     bool received;
  28 } GlobalState;
  29
  30 static GlobalState global_state;
  31
  32 int global_state_store(void)
  33 {
  34     if (!runstate_store((char *)global_state.runstate,
  35                         sizeof(global_state.runstate))) {
  36         error_report("runstate name too big: %s", global_state.runstate);
  37         trace_migrate_state_too_big();
  38         return -EINVAL;
  39     }
  40     return 0;
  41 }
  42
  43 void global_state_store_running(void)
  44 {
  45     const char *state = RunState_str(RUN_STATE_RUNNING);
  46     assert(strlen(state) < sizeof(global_state.runstate));
  47     strpadcpy((char *)global_state.runstate, sizeof(global_state.runstate),
  48               state, '\0');
  49 }
  50
  51 bool global_state_received(void)
  52 {
  53     return global_state.received;
  54 }
  55
  56 RunState global_state_get_runstate(void)
  57 {
  58     return global_state.state;
  59 }
  60
  61 static bool global_state_needed(void *opaque)
  62 {
  63     GlobalState *s = opaque;
  64     char *runstate = (char *)s->runstate;
  65
  66     /* If it is not optional, it is mandatory */
  67
  68     if (migrate_get_current()->store_global_state) {
  69         return true;
  70     }
  71
  72     /* If state is running or paused, it is not needed */
  73
  74     if (strcmp(runstate, "running") == 0 ||
  75         strcmp(runstate, "paused") == 0) {
  76         return false;
  77     }
  78
  79     /* for any other state it is needed */
  80     return true;
  81 }
  82
  83 static int global_state_post_load(void *opaque, int version_id)
  84 {
  85     GlobalState *s = opaque;
  86     Error *local_err = NULL;
  87     int r;
  88     char *runstate = (char *)s->runstate;
  89
  90     s->received = true;
  91     trace_migrate_global_state_post_load(runstate);
  92
  93     if (strnlen((char *)s->runstate,
  94                 sizeof(s->runstate)) == sizeof(s->runstate)) {
  95         /*
  96          * This condition should never happen during migration, because
  97          * all runstate names are shorter than 100 bytes (the size of
  98          * s->runstate). However, a malicious stream could overflow
  99          * the qapi_enum_parse() call, so we force the last character
 100          * to a NUL byte.
 101          */
 102         s->runstate[sizeof(s->runstate) - 1] = '\0';
 103     }
 104     r = qapi_enum_parse(&RunState_lookup, runstate, -1, &local_err);
 105
 106     if (r == -1) {
 107         if (local_err) {
 108             error_report_err(local_err);
 109         }
 110         return -EINVAL;
 111     }
 112     s->state = r;
 113
 114     return 0;
 115 }
 116
 117 static int global_state_pre_save(void *opaque)
 118 {
 119     GlobalState *s = opaque;
 120
 121     trace_migrate_global_state_pre_save((char *)s->runstate);
 122     s->size = strnlen((char *)s->runstate, sizeof(s->runstate)) + 1;
 123     assert(s->size <= sizeof(s->runstate));
 124
 125     return 0;
 126 }
 127
 128 static const VMStateDescription vmstate_globalstate = {
 129     .name = "globalstate",
 130     .version_id = 1,
 131     .minimum_version_id = 1,
 132     .post_load = global_state_post_load,
 133     .pre_save = global_state_pre_save,
 134     .needed = global_state_needed,
 135     .fields = (VMStateField[]) {
 136         VMSTATE_UINT32(size, GlobalState),
 137         VMSTATE_BUFFER(runstate, GlobalState),
 138         VMSTATE_END_OF_LIST()
 139     },
 140 };
 141
 142 void register_global_state(void)
 143 {
 144     /* We would use it independently that we receive it */
 145     strcpy((char *)&global_state.runstate, "");
 146     global_state.received = false;
 147     vmstate_register(NULL, 0, &vmstate_globalstate, &global_state);
 148 }