Re: [Qemu-devel] [PATCH 14/16] cpus-common: Introduce async_safe_run_on_cpu()
Paolo Bonzini writes:
> Signed-off-by: Paolo Bonzini
Reviewed-by: Alex Bennée
> ---
> cpus-common.c | 33 +++--
> include/qom/cpu.h | 14 ++
> 2 files changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/cpus-common.c b/cpus-common.c
> index 429652c..38b1d55 100644
> --- a/cpus-common.c
> +++ b/cpus-common.c
> @@ -18,6 +18,7 @@
> */
>
> #include "qemu/osdep.h"
> +#include "qemu/main-loop.h"
> #include "exec/cpu-common.h"
> #include "qom/cpu.h"
> #include "sysemu/cpus.h"
> @@ -106,7 +107,7 @@ struct qemu_work_item {
> struct qemu_work_item *next;
> run_on_cpu_func func;
> void *data;
> -bool free, done;
> +bool free, exclusive, done;
> };
>
> static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
> @@ -139,6 +140,7 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
> void *data,
> wi.data = data;
> wi.done = false;
> wi.free = false;
> +wi.exclusive = false;
>
> queue_work_on_cpu(cpu, &wi);
> while (!atomic_mb_read(&wi.done)) {
> @@ -229,6 +231,19 @@ void cpu_exec_end(CPUState *cpu)
> qemu_mutex_unlock(&qemu_cpu_list_lock);
> }
>
> +void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data)
> +{
> +struct qemu_work_item *wi;
> +
> +wi = g_malloc0(sizeof(struct qemu_work_item));
> +wi->func = func;
> +wi->data = data;
> +wi->free = true;
> +wi->exclusive = true;
> +
> +queue_work_on_cpu(cpu, wi);
> +}
> +
> void process_queued_cpu_work(CPUState *cpu)
> {
> struct qemu_work_item *wi;
> @@ -245,7 +260,21 @@ void process_queued_cpu_work(CPUState *cpu)
> cpu->queued_work_last = NULL;
> }
> qemu_mutex_unlock(&cpu->work_mutex);
> -wi->func(cpu, wi->data);
> +if (wi->exclusive) {
> +/* Running work items outside the BQL avoids the following
> deadlock:
> + * 1) start_exclusive() is called with the BQL taken while
> another
> + * CPU is running; 2) cpu_exec in the other CPU tries to takes
> the
> + * BQL, so it goes to sleep; start_exclusive() is sleeping too,
> so
> + * neither CPU can proceed.
> + */
> +qemu_mutex_unlock_iothread();
> +start_exclusive();
> +wi->func(cpu, wi->data);
> +end_exclusive();
> +qemu_mutex_lock_iothread();
> +} else {
> +wi->func(cpu, wi->data);
> +}
> qemu_mutex_lock(&cpu->work_mutex);
> if (wi->free) {
> g_free(wi);
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 934c07a..4092dd9 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -656,6 +656,20 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func,
> void *data);
> void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
>
> /**
> + * async_safe_run_on_cpu:
> + * @cpu: The vCPU to run on.
> + * @func: The function to be executed.
> + * @data: Data to pass to the function.
> + *
> + * Schedules the function @func for execution on the vCPU @cpu
> asynchronously,
> + * while all other vCPUs are sleeping.
> + *
> + * Unlike run_on_cpu and async_run_on_cpu, the function is run outside the
> + * BQL.
> + */
> +void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
> +
> +/**
> * qemu_get_cpu:
> * @index: The CPUState@cpu_index value of the CPU to obtain.
> *
--
Alex Bennée
Re: [Qemu-devel] [PATCH 14/16] cpus-common: Introduce async_safe_run_on_cpu()
On 09/23/2016 12:31 AM, Paolo Bonzini wrote: Signed-off-by: Paolo Bonzini --- cpus-common.c | 33 +++-- include/qom/cpu.h | 14 ++ 2 files changed, 45 insertions(+), 2 deletions(-) Reviewed-by: Richard Henderson r~
[Qemu-devel] [PATCH 14/16] cpus-common: Introduce async_safe_run_on_cpu()
Signed-off-by: Paolo Bonzini
---
cpus-common.c | 33 +++--
include/qom/cpu.h | 14 ++
2 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/cpus-common.c b/cpus-common.c
index 429652c..38b1d55 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -18,6 +18,7 @@
*/
#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
#include "exec/cpu-common.h"
#include "qom/cpu.h"
#include "sysemu/cpus.h"
@@ -106,7 +107,7 @@ struct qemu_work_item {
struct qemu_work_item *next;
run_on_cpu_func func;
void *data;
-bool free, done;
+bool free, exclusive, done;
};
static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
@@ -139,6 +140,7 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
void *data,
wi.data = data;
wi.done = false;
wi.free = false;
+wi.exclusive = false;
queue_work_on_cpu(cpu, &wi);
while (!atomic_mb_read(&wi.done)) {
@@ -229,6 +231,19 @@ void cpu_exec_end(CPUState *cpu)
qemu_mutex_unlock(&qemu_cpu_list_lock);
}
+void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data)
+{
+struct qemu_work_item *wi;
+
+wi = g_malloc0(sizeof(struct qemu_work_item));
+wi->func = func;
+wi->data = data;
+wi->free = true;
+wi->exclusive = true;
+
+queue_work_on_cpu(cpu, wi);
+}
+
void process_queued_cpu_work(CPUState *cpu)
{
struct qemu_work_item *wi;
@@ -245,7 +260,21 @@ void process_queued_cpu_work(CPUState *cpu)
cpu->queued_work_last = NULL;
}
qemu_mutex_unlock(&cpu->work_mutex);
-wi->func(cpu, wi->data);
+if (wi->exclusive) {
+/* Running work items outside the BQL avoids the following
deadlock:
+ * 1) start_exclusive() is called with the BQL taken while another
+ * CPU is running; 2) cpu_exec in the other CPU tries to takes the
+ * BQL, so it goes to sleep; start_exclusive() is sleeping too, so
+ * neither CPU can proceed.
+ */
+qemu_mutex_unlock_iothread();
+start_exclusive();
+wi->func(cpu, wi->data);
+end_exclusive();
+qemu_mutex_lock_iothread();
+} else {
+wi->func(cpu, wi->data);
+}
qemu_mutex_lock(&cpu->work_mutex);
if (wi->free) {
g_free(wi);
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 934c07a..4092dd9 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -656,6 +656,20 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func, void
*data);
void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
/**
+ * async_safe_run_on_cpu:
+ * @cpu: The vCPU to run on.
+ * @func: The function to be executed.
+ * @data: Data to pass to the function.
+ *
+ * Schedules the function @func for execution on the vCPU @cpu asynchronously,
+ * while all other vCPUs are sleeping.
+ *
+ * Unlike run_on_cpu and async_run_on_cpu, the function is run outside the
+ * BQL.
+ */
+void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
+
+/**
* qemu_get_cpu:
* @index: The CPUState@cpu_index value of the CPU to obtain.
*
--
2.7.4
Re: [Qemu-devel] [PATCH 14/16] cpus-common: Introduce async_safe_run_on_cpu()
On 21/09/2016 18:08, Emilio G. Cota wrote:
> On Mon, Sep 19, 2016 at 14:50:57 +0200, Paolo Bonzini wrote:
>> We have to run safe work items outside the BQL; for now keep other
>> work items within the BQL, though this can be changed relatively
>> easily as a follow-up.
>>
>> Signed-off-by: Paolo Bonzini
>> ---
>> cpus-common.c | 33 +++--
>> include/qom/cpu.h | 14 ++
>> 2 files changed, 45 insertions(+), 2 deletions(-)
>>
>> diff --git a/cpus-common.c b/cpus-common.c
>> index 6adc982..f7ad534 100644
>> --- a/cpus-common.c
>> +++ b/cpus-common.c
>> @@ -106,7 +106,7 @@ struct qemu_work_item {
>> struct qemu_work_item *next;
>> run_on_cpu_func func;
>> void *data;
>> -bool free, done;
>> +bool free, exclusive, done;
>> };
>>
>> static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
>> @@ -139,6 +139,7 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
>> void *data,
>> wi.data = data;
>> wi.done = false;
>> wi.free = false;
>> +wi.exclusive = false;
>>
>> queue_work_on_cpu(cpu, &wi);
>> while (!atomic_mb_read(&wi.done)) {
>> @@ -157,6 +158,7 @@ void async_run_on_cpu(CPUState *cpu, run_on_cpu_func
>> func, void *data)
>> wi->func = func;
>> wi->data = data;
>> wi->free = true;
>> +wi->exclusive = false;
>
> Just a very pedantic nit: in patch 08/19 we don't set wi->done false because
> there's a malloc0 right above this. So we might want to do the same here.
>
> E.
>
Ok.
Paolo
Re: [Qemu-devel] [PATCH 14/16] cpus-common: Introduce async_safe_run_on_cpu()
On Mon, Sep 19, 2016 at 14:50:57 +0200, Paolo Bonzini wrote:
> We have to run safe work items outside the BQL; for now keep other
> work items within the BQL, though this can be changed relatively
> easily as a follow-up.
>
> Signed-off-by: Paolo Bonzini
> ---
> cpus-common.c | 33 +++--
> include/qom/cpu.h | 14 ++
> 2 files changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/cpus-common.c b/cpus-common.c
> index 6adc982..f7ad534 100644
> --- a/cpus-common.c
> +++ b/cpus-common.c
> @@ -106,7 +106,7 @@ struct qemu_work_item {
> struct qemu_work_item *next;
> run_on_cpu_func func;
> void *data;
> -bool free, done;
> +bool free, exclusive, done;
> };
>
> static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
> @@ -139,6 +139,7 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
> void *data,
> wi.data = data;
> wi.done = false;
> wi.free = false;
> +wi.exclusive = false;
>
> queue_work_on_cpu(cpu, &wi);
> while (!atomic_mb_read(&wi.done)) {
> @@ -157,6 +158,7 @@ void async_run_on_cpu(CPUState *cpu, run_on_cpu_func
> func, void *data)
> wi->func = func;
> wi->data = data;
> wi->free = true;
> +wi->exclusive = false;
Just a very pedantic nit: in patch 08/19 we don't set wi->done false because
there's a malloc0 right above this. So we might want to do the same here.
E.
[Qemu-devel] [PATCH 14/16] cpus-common: Introduce async_safe_run_on_cpu()
We have to run safe work items outside the BQL; for now keep other
work items within the BQL, though this can be changed relatively
easily as a follow-up.
Signed-off-by: Paolo Bonzini
---
cpus-common.c | 33 +++--
include/qom/cpu.h | 14 ++
2 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/cpus-common.c b/cpus-common.c
index 6adc982..f7ad534 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -106,7 +106,7 @@ struct qemu_work_item {
struct qemu_work_item *next;
run_on_cpu_func func;
void *data;
-bool free, done;
+bool free, exclusive, done;
};
static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
@@ -139,6 +139,7 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
void *data,
wi.data = data;
wi.done = false;
wi.free = false;
+wi.exclusive = false;
queue_work_on_cpu(cpu, &wi);
while (!atomic_mb_read(&wi.done)) {
@@ -157,6 +158,7 @@ void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
void *data)
wi->func = func;
wi->data = data;
wi->free = true;
+wi->exclusive = false;
queue_work_on_cpu(cpu, wi);
}
@@ -230,6 +232,19 @@ void cpu_exec_end(CPUState *cpu)
qemu_mutex_unlock(&qemu_cpu_list_mutex);
}
+void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data)
+{
+struct qemu_work_item *wi;
+
+wi = g_malloc0(sizeof(struct qemu_work_item));
+wi->func = func;
+wi->data = data;
+wi->free = true;
+wi->exclusive = true;
+
+queue_work_on_cpu(cpu, wi);
+}
+
void process_queued_cpu_work(CPUState *cpu)
{
struct qemu_work_item *wi;
@@ -246,7 +261,21 @@ void process_queued_cpu_work(CPUState *cpu)
cpu->queued_work_last = NULL;
}
qemu_mutex_unlock(&cpu->work_mutex);
-wi->func(cpu, wi->data);
+if (wi->exclusive) {
+ /* Running work items outside the BQL avoids the following deadlock:
+* 1) start_exclusive() is called with the BQL taken while another
+ * CPU is running; 2) cpu_exec in the other CPU tries to takes the
+ * BQL, so it goes to sleep; start_exclusive() is sleeping too, so
+ * neither CPU can proceed.
+ */
+qemu_mutex_unlock_iothread();
+start_exclusive();
+wi->func(cpu, wi->data);
+end_exclusive();
+qemu_mutex_lock_iothread();
+} else {
+wi->func(cpu, wi->data);
+}
qemu_mutex_lock(&cpu->work_mutex);
if (wi->free) {
g_free(wi);
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 934c07a..4092dd9 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -656,6 +656,20 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func, void
*data);
void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
/**
+ * async_safe_run_on_cpu:
+ * @cpu: The vCPU to run on.
+ * @func: The function to be executed.
+ * @data: Data to pass to the function.
+ *
+ * Schedules the function @func for execution on the vCPU @cpu asynchronously,
+ * while all other vCPUs are sleeping.
+ *
+ * Unlike run_on_cpu and async_run_on_cpu, the function is run outside the
+ * BQL.
+ */
+void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
+
+/**
* qemu_get_cpu:
* @index: The CPUState@cpu_index value of the CPU to obtain.
*
--
2.7.4
[Qemu-devel] [PATCH 14/16] cpus-common: Introduce async_safe_run_on_cpu()
Signed-off-by: Paolo Bonzini
---
cpus-common.c | 25 +++--
include/qom/cpu.h | 11 +++
2 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/cpus-common.c b/cpus-common.c
index 12c8e69..50a92dd 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -106,7 +106,7 @@ struct qemu_work_item {
struct qemu_work_item *next;
run_on_cpu_func func;
void *data;
-bool free, done;
+bool free, exclusive, done;
};
static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
@@ -139,6 +139,7 @@ void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
void *data,
wi.data = data;
wi.done = false;
wi.free = false;
+wi.exclusive = false;
queue_work_on_cpu(cpu, &wi);
while (!atomic_mb_read(&wi.done)) {
@@ -157,6 +158,7 @@ void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func,
void *data)
wi->func = func;
wi->data = data;
wi->free = true;
+wi->exclusive = false;
queue_work_on_cpu(cpu, wi);
}
@@ -230,6 +232,19 @@ void cpu_exec_end(CPUState *cpu)
qemu_mutex_unlock(&qemu_cpu_list_mutex);
}
+void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data)
+{
+struct qemu_work_item *wi;
+
+wi = g_malloc0(sizeof(struct qemu_work_item));
+wi->func = func;
+wi->data = data;
+wi->free = true;
+wi->exclusive = true;
+
+queue_work_on_cpu(cpu, wi);
+}
+
void process_queued_cpu_work(CPUState *cpu)
{
struct qemu_work_item *wi;
@@ -246,7 +261,13 @@ void process_queued_cpu_work(CPUState *cpu)
cpu->queued_work_last = NULL;
}
qemu_mutex_unlock(&cpu->work_mutex);
-wi->func(cpu, wi->data);
+if (wi->exclusive) {
+start_exclusive();
+wi->func(cpu, wi->data);
+end_exclusive();
+} else {
+wi->func(cpu, wi->data);
+}
qemu_mutex_lock(&cpu->work_mutex);
if (wi->free) {
g_free(wi);
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 934c07a..d1ca31c 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -656,6 +656,17 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func, void
*data);
void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
/**
+ * async_safe_run_on_cpu:
+ * @cpu: The vCPU to run on.
+ * @func: The function to be executed.
+ * @data: Data to pass to the function.
+ *
+ * Schedules the function @func for execution on the vCPU @cpu asynchronously,
+ * while all other vCPUs are sleeping.
+ */
+void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
+
+/**
* qemu_get_cpu:
* @index: The CPUState@cpu_index value of the CPU to obtain.
*
--
2.7.4
