This patch joins replay event id and async event id into single byte in the log.
It makes processing a bit faster and log a bit smaller.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

--

v2: minor enum fixes (suggested by Richard Henderson)
Message-Id: <165364838393.688121.8191379555130516329.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch decouples checkpoints and async events.
It was a tricky part of replay implementation. Now it becomes
much simpler and easier to maintain.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <165364837856.688121.8785039478408995979.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch fixes event queue flush in the case of emulator
shutdown. replay_finish_events should be called when replay_mode
is not cleared.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <165364836758.688121.7959245442743676491.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

g_new(T, n) is neater than g_malloc(sizeof(T) * n).  It's also safer,
for two reasons.  One, it catches multiplication overflowing size_t.
Two, it returns T * rather than void *, which lets the compiler catch
more type errors.

This commit only touches allocations with size arguments of the form
sizeof(T).

Patch created mechanically with:

    $ spatch --in-place --sp-file scripts/coccinelle/use-g_new-etc.cocci \
	     --macro-file scripts/cocci-macro-file.h FILES...

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20220315144156.1595462-4-armbru@redhat.com>
Reviewed-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>

This patch enables vCPU notification to wake it up
when new async event comes in replay mode.

The motivation of this patch is the following.
Consider recorded block async event. It is saved into the log
with one of the checkpoints. This checkpoint may be passed in
vCPU loop. In replay mode when this async event is read from
the log, and block thread task is not finished yet, vCPU thread
goes to sleep. That is why this patch adds waking up the vCPU
to process this finished event.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <161726519158.1476949.7614181684462079836.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Record/replay uses checkpoints to synchronize the execution
of the threads and timers. Hardware events such as BH are
processed at the checkpoints too.
Event processing can cause refreshing the virtual timers
and calling the icount-related functions, that also use checkpoints.
This patch prevents recursive processing of such checkpoints,
because they have their own records in the log and should be
processed later.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <161700476500.1140362.10108444973730452257.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Record/replay provides REPLAY_CLOCK_LOCKED macro to access
the clock when vm_clock_seqlock is locked. This macro is
needed because replay internals operate icount. In locked case
replay use icount_get_raw_locked for icount request, which prevents
excess locking which leads to deadlock. But previously only
record code used *_locked function and replay did not.
Therefore sometimes clock access lead to deadlocks.
This patch fixes clock access for replay too and uses *_locked
icount access function.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <161347990483.1313189.8371838968343494161.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Modify load_snapshot/save_snapshot to accept the device list and vmstate
node name parameters previously added to the block layer.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-9-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The traditional HMP "savevm" command will overwrite an existing snapshot
if it already exists with the requested name. This new flag allows this
to be controlled allowing for safer behaviour with a future QMP command.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-8-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Currently bdrv_all_find_snapshot() will return 0 if it finds
a snapshot, -1 if an error occurs, or if it fails to find a
snapshot. New callers to be added want to distinguish between
the error scenario and failing to find a snapshot.

Rename it to bdrv_all_has_snapshot and make it return -1 on
error, 0 if no snapshot is found and 1 if snapshot is found.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-7-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Currently the vmstate will be stored in the first block device that
supports snapshots. Historically this would have usually been the
root device, but with UEFI it might be the variable store. There
needs to be a way to override the choice of block device to store
the state in.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-6-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

When running snapshot operations, there are various rules for which
blockdevs are included/excluded. While this provides reasonable default
behaviour, there are scenarios that are not well handled by the default
logic. Some of the conditions do not have a single correct answer.

Thus there needs to be a way for the mgmt app to provide an explicit
list of blockdevs to perform snapshots across. This can be achieved
by passing a list of node names that should be used.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-5-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

None of the callers care about the errno value since there is a full
Error object populated. This gives consistency with save_snapshot()
which already just returns a boolean value.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Return false/true instead of -1/0, document function]
Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210204124834.774401-4-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Just for consistency, following the example documented since
commit e3fe3988 ("error: Document Error API usage rules"),
return a boolean value indicating an error is set or not.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210204124834.774401-3-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The bdrv_all_*_snapshot functions return a BlockDriverState pointer
for the invalid backend, which the callers then use to report an
error message. In some cases multiple callers are reporting the
same error message, but with slightly different text. In the future
there will be more error scenarios for some of these methods, which
will benefit from fine grained error message reporting. So it is
helpful to push error reporting down a level.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Initialize variables]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210204124834.774401-2-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

This commit is the result of running the timer-del-timer-free.cocci
script on the whole source tree.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201215154107.3255-4-peter.maydell@linaro.org

This patch removes dead code in replay_continue_stop() function.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Reported-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <160455661411.3455.4177953912304752892.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

this fixes non-TCG builds broken recently by replay reverse debugging.

Stub the needed functions in stub/, splitting roughly between functions
needed only by system emulation, by system emulation and tools,
and by everyone.  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>
Message-Id: <20201013192123.22632-4-cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

When record/replay does not uses overlays for storing the snapshots,
user is not capable of issuing reverse debugging commands.
This patch adds creation of the VM snapshot on the temporary
overlay image, when the debugger connects to QEMU.
Therefore the execution can be rewind to the moment
of the debugger connection while debugging the virtual machine.

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

--

v6:
 - dropped unused error processing (suggested by Philippe Mathieu-Daudé)
Message-Id: <160174524096.12451.11651270339216758643.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch adds support of the reverse continue operation for gdbstub.
Reverse continue finds the last breakpoint that would happen in normal
execution from the beginning to the current moment.
Implementation of the reverse continue replays the execution twice:
to find the breakpoints that were hit and to seek to the last breakpoint.
Reverse continue loads the previous snapshot and tries to find the breakpoint
since that moment. If there are no such breakpoints, it proceeds to
the earlier snapshot, and so on. When no breakpoints or watchpoints were
hit at all, execution stops at the beginning of the replay log.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <160174522930.12451.6994758004725016836.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

GDB remote protocol supports two reverse debugging commands:
reverse step and reverse continue.
This patch adds support of the first one to the gdbstub.
Reverse step is intended to step one instruction in the backwards
direction. This is not possible in regular execution.
But replayed execution is deterministic, therefore we can load one of
the prior snapshots and proceed to the desired step. It is equivalent
to stepping one instruction back.
There should be at least one snapshot preceding the debugged part of
the replay log.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

--

v4 changes:
 - inverted condition in cpu_handle_guest_debug (suggested by Alex Bennée)
Message-Id: <160174522341.12451.1498758422543765253.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Non-empty record/replay queue prevents saving and loading the VM state,
because it includes pending bottom halves and block coroutines.
But when the new VM state is loaded, we don't have to preserve the consistency
of the current state anymore. Therefore this patch just flushes the queue
allowing the coroutines to finish and removes checking for empty rr queue
for load_snapshot function.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <160174521762.12451.15752448887893855757.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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.Dovgalyuk@ispras.ru>
Acked-by: Markus Armbruster <armbru@redhat.com>

--

v4 changes:
 - fixed HMP command description indent
 - removed useless error_free call
Message-Id: <160174521180.12451.14033112911009278753.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch introduces replay_break, replay_delete_break
qmp and hmp commands.
These commands allow stopping at the specified instruction.
It may be useful for debugging when there are some known
events that should be investigated.
replay_break command has one argument - number of instructions
executed since the start of the replay.
replay_delete_break removes previously set breakpoint.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Markus Armbruster <armbru@redhat.com>

--

v4 changes:
 - removed useless error_free call
Message-Id: <160174520606.12451.7056879546045599378.stgit@pasha-ThinkPad-X280>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch introduces 'info replay' monitor command and
corresponding qmp request.
These commands request the current record/replay mode, replay log file
name, and the instruction count (number of recorded/replayed
instructions).  The instruction count can be used with the
replay_seek/replay_break commands added in the next two patches.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <160174520026.12451.13112161947433306561.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch adds an accessor function for the name of the record/replay
log file. Adding an accessor instead of making variable global,
prevents accidental modification of this variable by other modules.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <160174517710.12451.17645787545733927488.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

refactoring of cpus.c continues with cpu timer state extraction.

cpu-timers: responsible for the softmmu cpu timers state,
            including cpu clocks and ticks.

icount: counts the TCG instructions executed. As such it is specific to
the TCG accelerator. Therefore, it is built only under CONFIG_TCG.

One complication is due to qtest, which uses an icount field to warp time
as part of qtest (qtest_clock_warp).

In order to solve this problem, provide a separate counter for qtest.

This requires fixing assumptions scattered in the code that
qtest_enabled() implies icount_enabled(), checking each specific case.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[remove redundant initialization with qemu_spice_init]
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
[fix lingering calls to icount_get]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Sometimes virtual timer callbacks depend on order
of virtual timer processing and warping of virtual clock.
Therefore every callback should be logged to make replay deterministic.
This patch creates a checkpoint before every virtual timer callback.
With these checkpoints virtual timers processing and clock warping
events order is completely deterministic.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Acked-by: Alex Bennée <alex.bennee@linaro.org>

--

v2:
  - remove mutex lock/unlock for virtual clock checkpoint since it is
    not process any asynchronous events (commit ca9759c2)
  - bump record/replay log file version
Message-Id: <159012932716.27256.8854065545365559921.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

When QEMU is used without any graphical window,
QEMU execution is terminated with the signal (e.g., Ctrl-C).
Signal processing in QEMU does not include
qemu_system_shutdown_request call. That is why shutdown
event is not recorded by record/replay in this case.
This patch adds shutdown event to the end of the record log.
Now every replay will shutdown the machine at the end.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <159012995470.27967.18129611453659045726.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

In record/replay icount mode main loop thread and vCPU thread
do not perform simultaneously. They take replay mutex to synchronize
the actions. Sometimes vCPU thread waits for locking the mutex for
very long time, because main loop releases the mutex and takes it
back again. Standard qemu mutex do not provide the ordering
capabilities.

This patch adds a "queue" for replay mutex. Therefore thread ordering
becomes more "fair". Threads are executed in the same order as
they are trying to take the mutex.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <158823802979.28101.9340462887738957616.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Record/replay feature of icount allows deterministic running of execution
scenarios. Some CPUs and peripheral devices read random numbers from
external sources making deterministic execution impossible.
This patch adds recording and replaying of random read operations
into guest-random module, which is used by the virtual hardware.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <157675984852.14505.15709141760677102489.stgit@pasha-Precision-3630-Tower>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Replay is capable of recording normal BH events, but sometimes
there are single use callbacks scheduled with aio_bh_schedule_oneshot
function. This patch enables recording and replaying such callbacks.
Block layer uses these events for calling the completion function.
Replaying these calls makes the execution deterministic.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

After recent updates block devices cannot be closed on qemu exit.
This happens due to the block request polling when replay is not finished.
Therefore now we stop execution recording before closing the block devices.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Kővágó, Zoltán <DirtY.iCE.hu@gmail.com>
Message-id: c5193e687fc6cc0f60cb3e90fe69ddf2027d0df1.1566168923.git.DirtY.iCE.hu@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

This patch renames replay_get_current_step() and related variables
to make these names consistent with existing 'icount' command line
option and future record/replay hmp/qmp commands.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <156404428377.18669.15476429889039912070.stgit@pasha-Precision-3630-Tower>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch removes refactoring artifacts from the replay/replay-time.c

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <156404427799.18669.8072341590511911277.stgit@pasha-Precision-3630-Tower>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This patch fixes shutdown of the replay process, which is terminated with
the assert when shutdown event is read from the log.
replay_finish_event reads new data_kind and therefore the value of data_kind
should be preserved to be valid at qemu_system_shutdown_request call.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <156404427238.18669.12378772823692338069.stgit@pasha-Precision-3630-Tower>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This is a fix which was missed by patch
74c0b816, which added current_step
parameter to the replay_advance_current_step function.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <156404425561.18669.13015037579222450241.stgit@pasha-Precision-3630-Tower>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>