Commit 53f5ed95 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

cpus-common: Introduce async_safe_run_on_cpu() 



Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 758e1b2b

cpus-common.c

+31 −2
Original line number Diff line number Diff line
@@ -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);

        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);

include/qom/cpu.h

+14 −0
Original line number Diff line number Diff line
@@ -655,6 +655,20 @@ 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.