Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 148 insertions, 0 deletions

diff --git a/migration/global_state.c b/migration/global_state.c
new file mode 100644
index 000000000..a33947ca3
--- /dev/null
+++ b/migration/global_state.c
@@ -0,0 +1,148 @@
+/*
+ * Global State configuration
+ *
+ * Copyright (c) 2014-2017 Red Hat Inc
+ *
+ * Authors:
+ *  Juan Quintela <quintela@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.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "qemu/error-report.h"
+#include "sysemu/runstate.h"
+#include "qapi/error.h"
+#include "migration.h"
+#include "migration/global_state.h"
+#include "migration/vmstate.h"
+#include "trace.h"
+
+typedef struct {
+    uint32_t size;
+    uint8_t runstate[100];
+    RunState state;
+    bool received;
+} GlobalState;
+
+static GlobalState global_state;
+
+int global_state_store(void)
+{
+    if (!runstate_store((char *)global_state.runstate,
+                        sizeof(global_state.runstate))) {
+        error_report("runstate name too big: %s", global_state.runstate);
+        trace_migrate_state_too_big();
+        return -EINVAL;
+    }
+    return 0;
+}
+
+void global_state_store_running(void)
+{
+    const char *state = RunState_str(RUN_STATE_RUNNING);
+    assert(strlen(state) < sizeof(global_state.runstate));
+    strpadcpy((char *)global_state.runstate, sizeof(global_state.runstate),
+              state, '\0');
+}
+
+bool global_state_received(void)
+{
+    return global_state.received;
+}
+
+RunState global_state_get_runstate(void)
+{
+    return global_state.state;
+}
+
+static bool global_state_needed(void *opaque)
+{
+    GlobalState *s = opaque;
+    char *runstate = (char *)s->runstate;
+
+    /* If it is not optional, it is mandatory */
+
+    if (migrate_get_current()->store_global_state) {
+        return true;
+    }
+
+    /* If state is running or paused, it is not needed */
+
+    if (strcmp(runstate, "running") == 0 ||
+        strcmp(runstate, "paused") == 0) {
+        return false;
+    }
+
+    /* for any other state it is needed */
+    return true;
+}
+
+static int global_state_post_load(void *opaque, int version_id)
+{
+    GlobalState *s = opaque;
+    Error *local_err = NULL;
+    int r;
+    char *runstate = (char *)s->runstate;
+
+    s->received = true;
+    trace_migrate_global_state_post_load(runstate);
+
+    if (strnlen((char *)s->runstate,
+                sizeof(s->runstate)) == sizeof(s->runstate)) {
+        /*
+         * This condition should never happen during migration, because
+         * all runstate names are shorter than 100 bytes (the size of
+         * s->runstate). However, a malicious stream could overflow
+         * the qapi_enum_parse() call, so we force the last character
+         * to a NUL byte.
+         */
+        s->runstate[sizeof(s->runstate) - 1] = '\0';
+    }
+    r = qapi_enum_parse(&RunState_lookup, runstate, -1, &local_err);
+
+    if (r == -1) {
+        if (local_err) {
+            error_report_err(local_err);
+        }
+        return -EINVAL;
+    }
+    s->state = r;
+
+    return 0;
+}
+
+static int global_state_pre_save(void *opaque)
+{
+    GlobalState *s = opaque;
+
+    trace_migrate_global_state_pre_save((char *)s->runstate);
+    s->size = strnlen((char *)s->runstate, sizeof(s->runstate)) + 1;
+    assert(s->size <= sizeof(s->runstate));
+
+    return 0;
+}
+
+static const VMStateDescription vmstate_globalstate = {
+    .name = "globalstate",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .post_load = global_state_post_load,
+    .pre_save = global_state_pre_save,
+    .needed = global_state_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(size, GlobalState),
+        VMSTATE_BUFFER(runstate, GlobalState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+void register_global_state(void)
+{
+    /* We would use it independently that we receive it */
+    strcpy((char *)&global_state.runstate, "");
+    global_state.received = false;
+    vmstate_register(NULL, 0, &vmstate_globalstate, &global_state);
+}