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)
---
include/sysemu/cpu-timers.h | 1 +
softmmu/icount.c | 8 ++++++++
stubs/icount.c | 4 ++++
util/async.c | 8 ++++++++
4 files changed, 21 insertions(+)
diff --git a/include/sysemu/cpu-timers.h b/include/sysemu/cpu-timers.h
index ed6ee5c46c..2e786fe7fb 100644
--- a/include/sysemu/cpu-timers.h
+++ b/include/sysemu/cpu-timers.h
@@ -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
diff --git a/softmmu/icount.c b/softmmu/icount.c
index 5ca271620d..1cafec5014 100644
--- a/softmmu/icount.c
+++ b/softmmu/icount.c
@@ -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);
+ }
+}
diff --git a/stubs/icount.c b/stubs/icount.c
index f13c43568b..6df8c2bf7d 100644
--- a/stubs/icount.c
+++ b/stubs/icount.c
@@ -43,3 +43,7 @@ void icount_account_warp_timer(void)
{
abort();
}
+
+void icount_notify_exit(void)
+{
+}
diff --git a/util/async.c b/util/async.c
index 554ba70cca..75f50f47c4 100644
--- a/util/async.c
+++ b/util/async.c
@@ -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"
/***********************************************************/
@@ -185,6 +186,13 @@ void qemu_bh_schedule_idle(QEMUBH *bh)
void qemu_bh_schedule(QEMUBH *bh)
{
aio_bh_enqueue(bh, BH_SCHEDULED);
+ /*
+ * 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();
}
/* This func is async.On 5/26/22 10:45, Pavel Dovgalyuk wrote:
> 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>
At least aio_bh_schedule_oneshot_full should have the same effect, so
should this be done at a lower level, in aio_bh_enqueue() or even
aio_notify()?
Paolo
> --
>
> v2: changed first_cpu to current_cpu (suggested by Richard Henderson)
> ---
> include/sysemu/cpu-timers.h | 1 +
> softmmu/icount.c | 8 ++++++++
> stubs/icount.c | 4 ++++
> util/async.c | 8 ++++++++
> 4 files changed, 21 insertions(+)
>
> diff --git a/include/sysemu/cpu-timers.h b/include/sysemu/cpu-timers.h
> index ed6ee5c46c..2e786fe7fb 100644
> --- a/include/sysemu/cpu-timers.h
> +++ b/include/sysemu/cpu-timers.h
> @@ -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
> diff --git a/softmmu/icount.c b/softmmu/icount.c
> index 5ca271620d..1cafec5014 100644
> --- a/softmmu/icount.c
> +++ b/softmmu/icount.c
> @@ -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);
> + }
> +}
> diff --git a/stubs/icount.c b/stubs/icount.c
> index f13c43568b..6df8c2bf7d 100644
> --- a/stubs/icount.c
> +++ b/stubs/icount.c
> @@ -43,3 +43,7 @@ void icount_account_warp_timer(void)
> {
> abort();
> }
> +
> +void icount_notify_exit(void)
> +{
> +}
> diff --git a/util/async.c b/util/async.c
> index 554ba70cca..75f50f47c4 100644
> --- a/util/async.c
> +++ b/util/async.c
> @@ -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"
>
> /***********************************************************/
> @@ -185,6 +186,13 @@ void qemu_bh_schedule_idle(QEMUBH *bh)
> void qemu_bh_schedule(QEMUBH *bh)
> {
> aio_bh_enqueue(bh, BH_SCHEDULED);
> + /*
> + * 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();
> }
>
> /* This func is async.
>
>
On 26.05.2022 12:37, Paolo Bonzini wrote:
> On 5/26/22 10:45, Pavel Dovgalyuk wrote:
>> 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>
>
> At least aio_bh_schedule_oneshot_full should have the same effect, so
> should this be done at a lower level, in aio_bh_enqueue() or even
> aio_notify()?
Not sure about aio_notify. It can operate with different contexts.
Can some of them be not related to the VM state?
Moving the notification to aio_bh_enqueue.
>
> Paolo
>
>> --
>>
>> v2: changed first_cpu to current_cpu (suggested by Richard Henderson)
>> ---
>> include/sysemu/cpu-timers.h | 1 +
>> softmmu/icount.c | 8 ++++++++
>> stubs/icount.c | 4 ++++
>> util/async.c | 8 ++++++++
>> 4 files changed, 21 insertions(+)
>>
>> diff --git a/include/sysemu/cpu-timers.h b/include/sysemu/cpu-timers.h
>> index ed6ee5c46c..2e786fe7fb 100644
>> --- a/include/sysemu/cpu-timers.h
>> +++ b/include/sysemu/cpu-timers.h
>> @@ -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
>> diff --git a/softmmu/icount.c b/softmmu/icount.c
>> index 5ca271620d..1cafec5014 100644
>> --- a/softmmu/icount.c
>> +++ b/softmmu/icount.c
>> @@ -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);
>> + }
>> +}
>> diff --git a/stubs/icount.c b/stubs/icount.c
>> index f13c43568b..6df8c2bf7d 100644
>> --- a/stubs/icount.c
>> +++ b/stubs/icount.c
>> @@ -43,3 +43,7 @@ void icount_account_warp_timer(void)
>> {
>> abort();
>> }
>> +
>> +void icount_notify_exit(void)
>> +{
>> +}
>> diff --git a/util/async.c b/util/async.c
>> index 554ba70cca..75f50f47c4 100644
>> --- a/util/async.c
>> +++ b/util/async.c
>> @@ -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"
>> /***********************************************************/
>> @@ -185,6 +186,13 @@ void qemu_bh_schedule_idle(QEMUBH *bh)
>> void qemu_bh_schedule(QEMUBH *bh)
>> {
>> aio_bh_enqueue(bh, BH_SCHEDULED);
>> + /*
>> + * 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();
>> }
>> /* This func is async.
>>
>>
>
On 5/26/22 11:51, Pavel Dovgalyuk wrote: >> >> At least aio_bh_schedule_oneshot_full should have the same effect, so >> should this be done at a lower level, in aio_bh_enqueue() or even >> aio_notify()? > > Not sure about aio_notify. It can operate with different contexts. > Can some of them be not related to the VM state? All but the main AioContext one would have current_cpu == NULL. Paolo > Moving the notification to aio_bh_enqueue.
On 26.05.2022 15:10, Paolo Bonzini wrote: > On 5/26/22 11:51, Pavel Dovgalyuk wrote: >>> >>> At least aio_bh_schedule_oneshot_full should have the same effect, so >>> should this be done at a lower level, in aio_bh_enqueue() or even >>> aio_notify()? >> >> Not sure about aio_notify. It can operate with different contexts. >> Can some of them be not related to the VM state? > > All but the main AioContext one would have current_cpu == NULL. aio_bh_enqueue is better. Moving this code to aio_notify breaks the tests.
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