diff mbox series

[v10,13/24] replay: implement replay-seek command

Message ID 20190117073804.5399.15509.stgit@pasha-VirtualBox (mailing list archive)
State New, archived
Headers show
Series Fixing record/replay and adding reverse debugging | expand

Commit Message

Pavel Dovgalyuk Jan. 17, 2019, 7:38 a.m. UTC
This patch adds hmp/qmp commands replay_seek/replay-seek that proceed
the execution to the specified instruction count.
The command automatically loads nearest snapshot and replays the execution
to find the desired instruction count.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>

--

v2:
 - renamed replay_seek qmp command into replay-seek
   (suggested by Eric Blake)
v7:
 - small fixes related to Markus Armbruster's review
v9:
 - changed 'step' parameter name to 'icount'
 - moved json stuff to replay.json and updated the description
   (suggested by Markus Armbruster)
v10:
 - updated the descriptions
---
 hmp-commands.hx           |   19 +++++++++
 hmp.h                     |    1 
 qapi/replay.json          |   20 ++++++++++
 replay/replay-debugging.c |   92 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 132 insertions(+)

Comments

Markus Armbruster Jan. 17, 2019, 1:30 p.m. UTC | #1
Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru> writes:

> This patch adds hmp/qmp commands replay_seek/replay-seek that proceed
> the execution to the specified instruction count.
> The command automatically loads nearest snapshot and replays the execution
> to find the desired instruction count.
>
> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
>
> --
>
> v2:
>  - renamed replay_seek qmp command into replay-seek
>    (suggested by Eric Blake)
> v7:
>  - small fixes related to Markus Armbruster's review
> v9:
>  - changed 'step' parameter name to 'icount'
>  - moved json stuff to replay.json and updated the description
>    (suggested by Markus Armbruster)
> v10:
>  - updated the descriptions
> ---
>  hmp-commands.hx           |   19 +++++++++
>  hmp.h                     |    1 
>  qapi/replay.json          |   20 ++++++++++
>  replay/replay-debugging.c |   92 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 132 insertions(+)
>
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index d529f24..57ec43c 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -1924,6 +1924,25 @@ The command is ignored when there are no replay breakpoints.
>  ETEXI
>  
>      {
> +        .name       = "replay_seek",
> +        .args_type  = "icount:i",
> +        .params     = "icount",
> +        .help       = "replay execution to the specified instruction count",
> +        .cmd        = hmp_replay_seek,
> +    },
> +
> +STEXI
> +@item replay_seek @var{icount}
> +@findex replay_seek
> +Automatically proceeds to the instruction count @var{icount}, when
> +replaying the execution. The command automatically loads nearest
> +snapshot and replays the execution to find the desired instruction.
> +When there is no preceding snapshot or the execution is not replayed,
> +then the command is ignored and error message is displayed.

Sounds like roundabout way to say "then the command fails".  If that's
correct, then let's phrase it that way.

> +icount for the reference may be observed with 'info replay' command.
> +ETEXI
> +
> +    {
>          .name       = "info",
>          .args_type  = "item:s?",
>          .params     = "[subcommand]",
> diff --git a/hmp.h b/hmp.h
> index c9b9b4f..d6e1d7e 100644
> --- a/hmp.h
> +++ b/hmp.h
> @@ -151,5 +151,6 @@ void hmp_info_sev(Monitor *mon, const QDict *qdict);
>  void hmp_info_replay(Monitor *mon, const QDict *qdict);
>  void hmp_replay_break(Monitor *mon, const QDict *qdict);
>  void hmp_replay_delete_break(Monitor *mon, const QDict *qdict);
> +void hmp_replay_seek(Monitor *mon, const QDict *qdict);
>  
>  #endif
> diff --git a/qapi/replay.json b/qapi/replay.json
> index cb94991..0b5afce 100644
> --- a/qapi/replay.json
> +++ b/qapi/replay.json
> @@ -99,3 +99,23 @@
>  #
>  ##
>  { 'command': 'replay-delete-break' }
> +
> +##
> +# @replay-seek:
> +#
> +# Automatically proceeds to the instruction count @icount, when
> +# replaying the execution. The command automatically loads nearest
> +# snapshot and replays the execution to find the desired instruction.
> +# When there is no preceding snapshot or the execution is not replayed,
> +# then the command is ignored and error is returned.
> +# icount for the reference may be obtained with @query-replay command.

My comment on hmp-commands.hx applies.

> +#
> +# @icount: target instruction count
> +#
> +# Since: 4.0
> +#
> +# Example:
> +#
> +# -> { "execute": "replay-seek", "data": { "icount": 220414 } }
> +##
> +{ 'command': 'replay-seek', 'data': { 'icount': 'int' } }

[...]

QAPI schema part
Acked-by: Markus Armbruster <armbru@redhat.com>

Please consider my comment suggestions regardless.
diff mbox series

Patch

diff --git a/hmp-commands.hx b/hmp-commands.hx
index d529f24..57ec43c 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1924,6 +1924,25 @@  The command is ignored when there are no replay breakpoints.
 ETEXI
 
     {
+        .name       = "replay_seek",
+        .args_type  = "icount:i",
+        .params     = "icount",
+        .help       = "replay execution to the specified instruction count",
+        .cmd        = hmp_replay_seek,
+    },
+
+STEXI
+@item replay_seek @var{icount}
+@findex replay_seek
+Automatically proceeds to the instruction count @var{icount}, when
+replaying the execution. The command automatically loads nearest
+snapshot and replays the execution to find the desired instruction.
+When there is no preceding snapshot or the execution is not replayed,
+then the command is ignored and error message is displayed.
+icount for the reference may be observed with 'info replay' command.
+ETEXI
+
+    {
         .name       = "info",
         .args_type  = "item:s?",
         .params     = "[subcommand]",
diff --git a/hmp.h b/hmp.h
index c9b9b4f..d6e1d7e 100644
--- a/hmp.h
+++ b/hmp.h
@@ -151,5 +151,6 @@  void hmp_info_sev(Monitor *mon, const QDict *qdict);
 void hmp_info_replay(Monitor *mon, const QDict *qdict);
 void hmp_replay_break(Monitor *mon, const QDict *qdict);
 void hmp_replay_delete_break(Monitor *mon, const QDict *qdict);
+void hmp_replay_seek(Monitor *mon, const QDict *qdict);
 
 #endif
diff --git a/qapi/replay.json b/qapi/replay.json
index cb94991..0b5afce 100644
--- a/qapi/replay.json
+++ b/qapi/replay.json
@@ -99,3 +99,23 @@ 
 #
 ##
 { 'command': 'replay-delete-break' }
+
+##
+# @replay-seek:
+#
+# Automatically proceeds to the instruction count @icount, when
+# replaying the execution. The command automatically loads nearest
+# snapshot and replays the execution to find the desired instruction.
+# When there is no preceding snapshot or the execution is not replayed,
+# then the command is ignored and error is returned.
+# icount for the reference may be obtained with @query-replay command.
+#
+# @icount: target instruction count
+#
+# Since: 4.0
+#
+# Example:
+#
+# -> { "execute": "replay-seek", "data": { "icount": 220414 } }
+##
+{ 'command': 'replay-seek', 'data': { 'icount': 'int' } }
diff --git a/replay/replay-debugging.c b/replay/replay-debugging.c
index a94685e..d99a9c1 100644
--- a/replay/replay-debugging.c
+++ b/replay/replay-debugging.c
@@ -18,6 +18,8 @@ 
 #include "qapi/qapi-commands-replay.h"
 #include "qapi/qmp/qdict.h"
 #include "qemu/timer.h"
+#include "block/snapshot.h"
+#include "migration/snapshot.h"
 
 void hmp_info_replay(Monitor *mon, const QDict *qdict)
 {
@@ -127,3 +129,93 @@  void hmp_replay_delete_break(Monitor *mon, const QDict *qdict)
         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 nb_sns, i;
+    AioContext *aio_context;
+
+    *snapshot_icount = -1;
+
+    bs = bdrv_all_find_vmstate_bs();
+    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++) {
+        if (bdrv_all_find_snapshot(sn_tab[i].name, &bs) == 0) {
+            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;
+    }
+    if (!replay_snapshot) {
+        error_setg(errp, "snapshotting is disabled");
+        return;
+    }
+
+    snapshot = replay_find_nearest_snapshot(icount, &snapshot_icount);
+    if (snapshot) {
+        if (icount < replay_get_current_step()
+            || replay_get_current_step() < snapshot_icount) {
+            vm_stop(RUN_STATE_RESTORE_VM);
+            load_snapshot(snapshot, errp);
+        }
+        g_free(snapshot);
+    }
+    if (replay_get_current_step() <= 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);
+        error_free(err);
+        return;
+    }
+}