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, 334 insertions, 0 deletions

diff --git a/replay/replay-debugging.c b/replay/replay-debugging.c
new file mode 100644
index 000000000..1cde50e9f
--- /dev/null
+++ b/replay/replay-debugging.c
@@ -0,0 +1,334 @@
+/*
+ * replay-debugging.c
+ *
+ * Copyright (c) 2010-2020 Institute for System Programming
+ *                         of the Russian Academy of Sciences.
+ *
+ * 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 "qapi/error.h"
+#include "sysemu/replay.h"
+#include "sysemu/runstate.h"
+#include "replay-internal.h"
+#include "monitor/hmp.h"
+#include "monitor/monitor.h"
+#include "qapi/qapi-commands-replay.h"
+#include "qapi/qmp/qdict.h"
+#include "qemu/timer.h"
+#include "block/snapshot.h"
+#include "migration/snapshot.h"
+
+static bool replay_is_debugging;
+static int64_t replay_last_breakpoint;
+static int64_t replay_last_snapshot;
+
+bool replay_running_debug(void)
+{
+    return replay_is_debugging;
+}
+
+void hmp_info_replay(Monitor *mon, const QDict *qdict)
+{
+    if (replay_mode == REPLAY_MODE_NONE) {
+        monitor_printf(mon, "Record/replay is not active\n");
+    } else {
+        monitor_printf(mon,
+            "%s execution '%s': instruction count = %"PRId64"\n",
+            replay_mode == REPLAY_MODE_RECORD ? "Recording" : "Replaying",
+            replay_get_filename(), replay_get_current_icount());
+    }
+}
+
+ReplayInfo *qmp_query_replay(Error **errp)
+{
+    ReplayInfo *retval = g_new0(ReplayInfo, 1);
+
+    retval->mode = replay_mode;
+    if (replay_get_filename()) {
+        retval->filename = g_strdup(replay_get_filename());
+        retval->has_filename = true;
+    }
+    retval->icount = replay_get_current_icount();
+    return retval;
+}
+
+static void replay_break(uint64_t icount, QEMUTimerCB callback, void *opaque)
+{
+    assert(replay_mode == REPLAY_MODE_PLAY);
+    assert(replay_mutex_locked());
+    assert(replay_break_icount >= replay_get_current_icount());
+    assert(callback);
+
+    replay_break_icount = icount;
+
+    if (replay_break_timer) {
+        timer_del(replay_break_timer);
+    }
+    replay_break_timer = timer_new_ns(QEMU_CLOCK_REALTIME,
+                                      callback, opaque);
+}
+
+static void replay_delete_break(void)
+{
+    assert(replay_mode == REPLAY_MODE_PLAY);
+    assert(replay_mutex_locked());
+
+    if (replay_break_timer) {
+        timer_free(replay_break_timer);
+        replay_break_timer = NULL;
+    }
+    replay_break_icount = -1ULL;
+}
+
+static void replay_stop_vm(void *opaque)
+{
+    vm_stop(RUN_STATE_PAUSED);
+    replay_delete_break();
+}
+
+void qmp_replay_break(int64_t icount, Error **errp)
+{
+    if (replay_mode == REPLAY_MODE_PLAY) {
+        if (icount >= replay_get_current_icount()) {
+            replay_break(icount, replay_stop_vm, NULL);
+        } else {
+            error_setg(errp,
+                "cannot set breakpoint at the instruction in the past");
+        }
+    } else {
+        error_setg(errp, "setting the breakpoint is allowed only in play mode");
+    }
+}
+
+void hmp_replay_break(Monitor *mon, const QDict *qdict)
+{
+    int64_t icount = qdict_get_try_int(qdict, "icount", -1LL);
+    Error *err = NULL;
+
+    qmp_replay_break(icount, &err);
+    if (err) {
+        error_report_err(err);
+        return;
+    }
+}
+
+void qmp_replay_delete_break(Error **errp)
+{
+    if (replay_mode == REPLAY_MODE_PLAY) {
+        replay_delete_break();
+    } else {
+        error_setg(errp, "replay breakpoints are allowed only in play mode");
+    }
+}
+
+void hmp_replay_delete_break(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+
+    qmp_replay_delete_break(&err);
+    if (err) {
+        error_report_err(err);
+        return;
+    }
+}
+
+static char *replay_find_nearest_snapshot(int64_t icount,
+                                          int64_t *snapshot_icount)
+{
+    BlockDriverState *bs;
+    QEMUSnapshotInfo *sn_tab;
+    QEMUSnapshotInfo *nearest = NULL;
+    char *ret = NULL;
+    int rv;
+    int nb_sns, i;
+    AioContext *aio_context;
+
+    *snapshot_icount = -1;
+
+    bs = bdrv_all_find_vmstate_bs(NULL, false, NULL, NULL);
+    if (!bs) {
+        goto fail;
+    }
+    aio_context = bdrv_get_aio_context(bs);
+
+    aio_context_acquire(aio_context);
+    nb_sns = bdrv_snapshot_list(bs, &sn_tab);
+    aio_context_release(aio_context);
+
+    for (i = 0; i < nb_sns; i++) {
+        rv = bdrv_all_has_snapshot(sn_tab[i].name, false, NULL, NULL);
+        if (rv < 0)
+            goto fail;
+        if (rv == 1) {
+            if (sn_tab[i].icount != -1ULL
+                && sn_tab[i].icount <= icount
+                && (!nearest || nearest->icount < sn_tab[i].icount)) {
+                nearest = &sn_tab[i];
+            }
+        }
+    }
+    if (nearest) {
+        ret = g_strdup(nearest->name);
+        *snapshot_icount = nearest->icount;
+    }
+    g_free(sn_tab);
+
+fail:
+    return ret;
+}
+
+static void replay_seek(int64_t icount, QEMUTimerCB callback, Error **errp)
+{
+    char *snapshot = NULL;
+    int64_t snapshot_icount;
+
+    if (replay_mode != REPLAY_MODE_PLAY) {
+        error_setg(errp, "replay must be enabled to seek");
+        return;
+    }
+
+    snapshot = replay_find_nearest_snapshot(icount, &snapshot_icount);
+    if (snapshot) {
+        if (icount < replay_get_current_icount()
+            || replay_get_current_icount() < snapshot_icount) {
+            vm_stop(RUN_STATE_RESTORE_VM);
+            load_snapshot(snapshot, NULL, false, NULL, errp);
+        }
+        g_free(snapshot);
+    }
+    if (replay_get_current_icount() <= icount) {
+        replay_break(icount, callback, NULL);
+        vm_start();
+    } else {
+        error_setg(errp, "cannot seek to the specified instruction count");
+    }
+}
+
+void qmp_replay_seek(int64_t icount, Error **errp)
+{
+    replay_seek(icount, replay_stop_vm, errp);
+}
+
+void hmp_replay_seek(Monitor *mon, const QDict *qdict)
+{
+    int64_t icount = qdict_get_try_int(qdict, "icount", -1LL);
+    Error *err = NULL;
+
+    qmp_replay_seek(icount, &err);
+    if (err) {
+        error_report_err(err);
+        return;
+    }
+}
+
+static void replay_stop_vm_debug(void *opaque)
+{
+    replay_is_debugging = false;
+    vm_stop(RUN_STATE_DEBUG);
+    replay_delete_break();
+}
+
+bool replay_reverse_step(void)
+{
+    Error *err = NULL;
+
+    assert(replay_mode == REPLAY_MODE_PLAY);
+
+    if (replay_get_current_icount() != 0) {
+        replay_seek(replay_get_current_icount() - 1,
+                    replay_stop_vm_debug, &err);
+        if (err) {
+            error_free(err);
+            return false;
+        }
+        replay_is_debugging = true;
+        return true;
+    }
+
+    return false;
+}
+
+static void replay_continue_end(void)
+{
+    replay_is_debugging = false;
+    vm_stop(RUN_STATE_DEBUG);
+    replay_delete_break();
+}
+
+static void replay_continue_stop(void *opaque)
+{
+    Error *err = NULL;
+    if (replay_last_breakpoint != -1LL) {
+        replay_seek(replay_last_breakpoint, replay_stop_vm_debug, &err);
+        if (err) {
+            error_free(err);
+            replay_continue_end();
+        }
+        return;
+    }
+    /*
+     * No breakpoints since the last snapshot.
+     * Find previous snapshot and try again.
+     */
+    if (replay_last_snapshot != 0) {
+        replay_seek(replay_last_snapshot - 1, replay_continue_stop, &err);
+        if (err) {
+            error_free(err);
+            replay_continue_end();
+        }
+        replay_last_snapshot = replay_get_current_icount();
+    } else {
+        /* Seek to the very first step */
+        replay_seek(0, replay_stop_vm_debug, &err);
+        if (err) {
+            error_free(err);
+            replay_continue_end();
+        }
+    }
+}
+
+bool replay_reverse_continue(void)
+{
+    Error *err = NULL;
+
+    assert(replay_mode == REPLAY_MODE_PLAY);
+
+    if (replay_get_current_icount() != 0) {
+        replay_seek(replay_get_current_icount() - 1,
+                    replay_continue_stop, &err);
+        if (err) {
+            error_free(err);
+            return false;
+        }
+        replay_last_breakpoint = -1LL;
+        replay_is_debugging = true;
+        replay_last_snapshot = replay_get_current_icount();
+        return true;
+    }
+
+    return false;
+}
+
+void replay_breakpoint(void)
+{
+    assert(replay_mode == REPLAY_MODE_PLAY);
+    replay_last_breakpoint = replay_get_current_icount();
+}
+
+void replay_gdb_attached(void)
+{
+    /*
+     * Create VM snapshot on temporary overlay to allow reverse
+     * debugging even if snapshots were not enabled.
+     */
+    if (replay_mode == REPLAY_MODE_PLAY
+        && !replay_snapshot) {
+        if (!save_snapshot("start_debugging", true, NULL, false, NULL, NULL)) {
+            /* Can't create the snapshot. Continue conventional debugging. */
+        }
+    }
+}