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replay: notify vCPU when BH is scheduled

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vCPU execution should be suspended when new BH is scheduled.
This is needed to avoid guest timeouts caused by the long cycles
of the execution. In replay mode execution may hang when
vCPU sleeps and block event comes to the queue.
This patch adds notification which wakes up vCPU or interrupts
execution of guest code.

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

--

v2: changed first_cpu to current_cpu (suggested by Richard Henderson)
v4: moved vCPU notification to aio_bh_enqueue (suggested by Paolo Bonzini)
Message-Id: <165364837317.688121.17680519919871405281.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Pavel Dovgalyuk 2022-05-27 13:46:13 +03:00 committed by Paolo Bonzini
parent c4b8ffcbb8
commit 75bbe5e5ec
4 changed files with 21 additions and 0 deletions
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1
include/sysemu/cpu-timers.h
View File

@ -59,6 +59,7 @@ int64_t icount_round(int64_t count);
/* if the CPUs are idle, start accounting real time to virtual clock. */
void icount_start_warp_timer(void);
void icount_account_warp_timer(void);
void icount_notify_exit(void);
/*
* CPU Ticks and Clock

8
softmmu/icount.c
View File

@ -486,3 +486,11 @@ void icount_configure(QemuOpts *opts, Error **errp)
qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
NANOSECONDS_PER_SECOND / 10);
}
void icount_notify_exit(void)
{
if (icount_enabled() && current_cpu) {
qemu_cpu_kick(current_cpu);
qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
}
}

4
stubs/icount.c
View File

@ -43,3 +43,7 @@ void icount_account_warp_timer(void)
{
abort();
}
void icount_notify_exit(void)
{
}

8
util/async.c
View File

@ -33,6 +33,7 @@
#include "block/raw-aio.h"
#include "qemu/coroutine_int.h"
#include "qemu/coroutine-tls.h"
#include "sysemu/cpu-timers.h"
#include "trace.h"
/***********************************************************/
@ -84,6 +85,13 @@ static void aio_bh_enqueue(QEMUBH *bh, unsigned new_flags)
}
aio_notify(ctx);
/*
* Workaround for record/replay.
* vCPU execution should be suspended when new BH is set.
* This is needed to avoid guest timeouts caused
* by the long cycles of the execution.
*/
icount_notify_exit();
}
/* Only called from aio_bh_poll() and aio_ctx_finalize() */