Re: [PATCH v4 3/3] replay: do not build if TCG is not available

[Claudio Fontana]

привет Pavel!

On 10/14/20 7:42 AM, Pavel Dovgalyuk wrote:
> On 13.10.2020 22:21, Claudio Fontana wrote:
>> this fixes non-TCG builds broken recently by replay reverse debugging.
>>
>> stub the needed functions in stub/, including errors for hmp and qmp.
>> This includes duplicating some code in replay/, and puts the logic
>> for non-replay related events in the replay/ module (+ the stubs),
>> so this should be revisited in the future.
>>
>> Surprisingly, only _one_ qtest was affected by this, ide-test.c, which
>> resulted in a buzz as the bh events were never delivered, and the bh
>> never executed.
>>
>> Many other subsystems _should_ have been affected.
>>
>> This fixes the immediate issue, however a better way to group replay
>> functionality to TCG-only code could be developed in the long term.
>>
>> Signed-off-by: Claudio Fontana <cfontana@suse.de>
>> ---
>>   block/meson.build          |  3 +-
>>   migration/savevm.c         | 11 +++--
>>   net/meson.build            |  3 +-
>>   replay/meson.build         |  2 +-
>>   replay/replay-input.c      |  4 +-
>>   stubs/meson.build          |  1 -
>>   stubs/replay-user.c        |  9 ----
>>   stubs/replay.c             | 98 ++++++++++++++++++++++++++++++++++++++
>>   tests/ptimer-test-stubs.c  |  5 --
>>   tests/qtest/qmp-cmd-test.c |  3 ++
>>   ui/input.c                 | 12 ++++-
>>   11 files changed, 125 insertions(+), 26 deletions(-)
>>   delete mode 100644 stubs/replay-user.c
>>
>> diff --git a/block/meson.build b/block/meson.build
>> index 78e8b25232..01fe6f84d2 100644
>> --- a/block/meson.build
>> +++ b/block/meson.build
>> @@ -7,7 +7,6 @@ block_ss.add(files(
>>     'backup-top.c',
>>     'blkdebug.c',
>>     'blklogwrites.c',
>> -  'blkreplay.c',
>>     'blkverify.c',
>>     'block-backend.c',
>>     'block-copy.c',
>> @@ -42,6 +41,8 @@ block_ss.add(files(
>>     'write-threshold.c',
>>   ), zstd, zlib)
>>   
>> +block_ss.add(when: 'CONFIG_TCG', if_true: files('blkreplay.c'))
>> +
>>   block_ss.add(when: 'CONFIG_QCOW1', if_true: files('qcow.c'))
>>   block_ss.add(when: 'CONFIG_VDI', if_true: files('vdi.c'))
>>   block_ss.add(when: 'CONFIG_CLOOP', if_true: files('cloop.c'))
>> diff --git a/migration/savevm.c b/migration/savevm.c
>> index d2e141f7b1..d9181ca520 100644
>> --- a/migration/savevm.c
>> +++ b/migration/savevm.c
>> @@ -63,6 +63,7 @@
>>   #include "migration/colo.h"
>>   #include "qemu/bitmap.h"
>>   #include "net/announce.h"
>> +#include "sysemu/tcg.h"
>>   
>>   const unsigned int postcopy_ram_discard_version = 0;
>>   
>> @@ -2674,10 +2675,12 @@ int save_snapshot(const char *name, Error **errp)
>>           return ret;
>>       }
>>   
>> -    if (!replay_can_snapshot()) {
>> -        error_setg(errp, "Record/replay does not allow making snapshot "
>> -                   "right now. Try once more later.");
>> -        return ret;
>> +    if (tcg_enabled()) {
>> +        if (!replay_can_snapshot()) {
>> +            error_setg(errp, "Record/replay does not allow making snapshot "
>> +                       "right now. Try once more later.");
>> +            return ret;
>> +        }
>>       }
>>   
>>       if (!bdrv_all_can_snapshot(&bs)) {
>> diff --git a/net/meson.build b/net/meson.build
>> index 1c7e3a3cb9..1076b0a7ab 100644
>> --- a/net/meson.build
>> +++ b/net/meson.build
>> @@ -7,7 +7,6 @@ softmmu_ss.add(files(
>>     'eth.c',
>>     'filter-buffer.c',
>>     'filter-mirror.c',
>> -  'filter-replay.c',
>>     'filter-rewriter.c',
>>     'filter.c',
>>     'hub.c',
>> @@ -17,6 +16,8 @@ softmmu_ss.add(files(
>>     'util.c',
>>   ))
>>   
>> +softmmu_ss.add(when: 'CONFIG_TCG', if_true: files('filter-replay.c'))
>> +
>>   softmmu_ss.add(when: 'CONFIG_L2TPV3', if_true: files('l2tpv3.c'))
>>   softmmu_ss.add(when: slirp, if_true: files('slirp.c'))
>>   softmmu_ss.add(when: ['CONFIG_VDE', vde], if_true: files('vde.c'))
>> diff --git a/replay/meson.build b/replay/meson.build
>> index f91163fb1e..cb3207740a 100644
>> --- a/replay/meson.build
>> +++ b/replay/meson.build
>> @@ -1,4 +1,4 @@
>> -softmmu_ss.add(files(
>> +softmmu_ss.add(when: 'CONFIG_TCG', if_true: files(
>>     'replay.c',
>>     'replay-internal.c',
>>     'replay-events.c',
>> diff --git a/replay/replay-input.c b/replay/replay-input.c
>> index 1147e3d34e..5d1fd92e79 100644
>> --- a/replay/replay-input.c
>> +++ b/replay/replay-input.c
>> @@ -124,7 +124,7 @@ void replay_input_event(QemuConsole *src, InputEvent 
>> *evt)
>>       } else if (replay_mode == REPLAY_MODE_RECORD) {
>>           replay_add_input_event(QAPI_CLONE(InputEvent, evt));
>>       } else {
>> -        qemu_input_event_send_impl(src, evt);
>> +        g_assert_not_reached();
>>       }
>>   }
>>   
>> @@ -135,6 +135,6 @@ void replay_input_sync_event(void)
>>       } else if (replay_mode == REPLAY_MODE_RECORD) {
>>           replay_add_input_sync_event();
>>       } else {
>> -        qemu_input_event_sync_impl();
>> +        g_assert_not_reached();
>>       }
>>   }


incidentally Pavel, is this ok when replay is enabled, can you give it a spin?
I used the if (replay_events_enabled()) in the ui/input.c code to only call 
these when events are enabled.



>> diff --git a/stubs/meson.build b/stubs/meson.build
>> index 67f2a8c069..bbd2230d69 100644
>> --- a/stubs/meson.build
>> +++ b/stubs/meson.build
>> @@ -32,7 +32,6 @@ stub_ss.add(files('qtest.c'))
>>   stub_ss.add(files('ram-block.c'))
>>   stub_ss.add(files('ramfb.c'))
>>   stub_ss.add(files('replay.c'))
>> -stub_ss.add(files('replay-user.c'))
>>   stub_ss.add(files('runstate-check.c'))
>>   stub_ss.add(files('set-fd-handler.c'))
>>   stub_ss.add(files('sysbus.c'))
>> diff --git a/stubs/replay-user.c b/stubs/replay-user.c
>> deleted file mode 100644
>> index 2ad9e27203..0000000000
>> --- a/stubs/replay-user.c
>> +++ /dev/null
>> @@ -1,9 +0,0 @@
>> -#include "qemu/osdep.h"
>> -#include "sysemu/replay.h"
>> -#include "sysemu/sysemu.h"
>> -
>> -void replay_bh_schedule_oneshot_event(AioContext *ctx,
>> -    QEMUBHFunc *cb, void *opaque)
>> -{
>> -    aio_bh_schedule_oneshot(ctx, cb, opaque);
>> -}
>> diff --git a/stubs/replay.c b/stubs/replay.c
>> index 45ebe77fb9..34b7975b2d 100644
>> --- a/stubs/replay.c
>> +++ b/stubs/replay.c
>> @@ -103,3 +103,101 @@ bool replay_reverse_continue(void)
>>   {
>>       return false;
>>   }
>> +
>> +void replay_input_event(QemuConsole *src, InputEvent *evt)
>> +{
>> +}
>> +void replay_input_sync_event(void)
>> +{
>> +}
>> +void replay_bh_schedule_event(QEMUBH *bh)
>> +{
>> +    qemu_bh_schedule(bh);
>> +}
>> +void replay_bh_schedule_oneshot_event(AioContext *ctx,
>> +     QEMUBHFunc *cb, void *opaque)
>> +{
>> +    aio_bh_schedule_oneshot(ctx, cb, opaque);
>> +}
>> +void replay_add_blocker(Error *reason)
>> +{
>> +}
>> +void replay_audio_in(size_t *recorded, void *samples, size_t *wpos, size_t 
>> size)
>> +{
>> +}
>> +void replay_audio_out(size_t *played)
>> +{
>> +}
>> +void replay_breakpoint(void)
>> +{
>> +}
>> +bool replay_can_snapshot(void)
>> +{
>> +    return false;
>> +}
> 
> Shouldn't this one return true to enable snapshotting?


The check for replay_can_snapshot is wrapped by a

if (tcg_enabled()) {
}

so it should be fine.

Logically, reading a naked:

if (!replay_can_snapshot()) { fail; }

is surprising I think for a reader that compiled the code without replay.

> 
> 
>> +void replay_configure(struct QemuOpts *opts)
>> +{
>> +}
>> +void replay_flush_events(void)
>> +{
>> +}
>> +void replay_gdb_attached(void)
>> +{
>> +}
>> +bool replay_running_debug(void)
>> +{
>> +    return false;
>> +}
>> +void replay_shutdown_request(ShutdownCause cause)
>> +{
>> +}
>> +void replay_start(void)
>> +{
>> +}
>> +void replay_vmstate_init(void)
>> +{
>> +}
>> +
>> +#include "monitor/monitor.h"
>> +#include "monitor/hmp.h"
>> +#include "qapi/qapi-commands-replay.h"
>> +#include "qapi/error.h"
>> +#include "qemu/error-report.h"
>> +
>> +void hmp_info_replay(Monitor *mon, const QDict *qdict)
>> +{
>> +    error_report("replay support not available");
>> +}
>> +void hmp_replay_break(Monitor *mon, const QDict *qdict)
>> +{
>> +    error_report("replay support not available");
>> +}
>> +void hmp_replay_delete_break(Monitor *mon, const QDict *qdict)
>> +{
>> +    error_report("replay support not available");
>> +}
>> +void hmp_replay_seek(Monitor *mon, const QDict *qdict)
>> +{
>> +    error_report("replay support not available");
>> +}
>> +ReplayInfo *qmp_query_replay(Error **errp)
>> +{
>> +    error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
>> +              "replay support not available");
>> +    return NULL;
>> +}
>> +void qmp_replay_break(int64_t icount, Error **errp)
>> +{
>> +    error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
>> +              "replay support not available");
>> +}
>> +void qmp_replay_delete_break(Error **errp)
>> +{
>> +    error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
>> +              "replay support not available");
>> +}
>> +void qmp_replay_seek(int64_t icount, Error **errp)
>> +{
>> +    error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
>> +              "replay support not available");
>> +}
>> diff --git a/tests/ptimer-test-stubs.c b/tests/ptimer-test-stubs.c
>> index e935a1395e..7f801a4d09 100644
>> --- a/tests/ptimer-test-stubs.c
>> +++ b/tests/ptimer-test-stubs.c
>> @@ -122,8 +122,3 @@ void qemu_bh_delete(QEMUBH *bh)
>>   {
>>       g_free(bh);
>>   }
>> -
>> -void replay_bh_schedule_event(QEMUBH *bh)
>> -{
>> -    bh->cb(bh->opaque);
>> -}
>> diff --git a/tests/qtest/qmp-cmd-test.c b/tests/qtest/qmp-cmd-test.c
>> index 8a4c570e83..1c7186e53c 100644
>> --- a/tests/qtest/qmp-cmd-test.c
>> +++ b/tests/qtest/qmp-cmd-test.c
>> @@ -31,6 +31,9 @@ static int query_error_class(const char *cmd)
>>   #ifndef CONFIG_SPICE
>>           { "query-spice", ERROR_CLASS_COMMAND_NOT_FOUND },
>>   #endif
>> +#ifndef CONFIG_TCG
>> +        { "query-replay", ERROR_CLASS_COMMAND_NOT_FOUND },
>> +#endif
>>   #ifndef CONFIG_VNC
>>           { "query-vnc", ERROR_CLASS_GENERIC_ERROR },
>>           { "query-vnc-servers", ERROR_CLASS_GENERIC_ERROR },
>> diff --git a/ui/input.c b/ui/input.c
>> index 4791b089c7..8675e8ad09 100644
>> --- a/ui/input.c
>> +++ b/ui/input.c
>> @@ -375,7 +375,11 @@ void qemu_input_event_send(QemuConsole *src, InputEvent 
>> *evt)
>>           return;
>>       }
>>   
>> -    replay_input_event(src, evt);
>> +    if (replay_events_enabled()) {
>> +        replay_input_event(src, evt);
>> +    } else {
>> +        qemu_input_event_send_impl(src, evt);
>> +    }
>>   }
>>   
>>   void qemu_input_event_sync_impl(void)
>> @@ -401,7 +405,11 @@ void qemu_input_event_sync(void)
>>           return;
>>       }
>>   
>> -    replay_input_sync_event();
>> +    if (replay_events_enabled()) {
>> +        replay_input_sync_event();
>> +    } else {
>> +        qemu_input_event_sync_impl();
>> +    }
>>   }
>>   
>>   static InputEvent *qemu_input_event_new_key(KeyValue *key, bool down)
>>
> 

Thanks!

Ciao,

Claudio