Commit 791158d9 authored by Alex Bennée's avatar Alex Bennée
Browse files

tcg: rename tcg_current_cpu to tcg_current_rr_cpu 



..and make the definition local to cpus. In preparation for MTTCG the
concept of a global tcg_current_cpu will no longer make sense. However
we still need to keep track of it in the single-threaded case to be able
to exit quickly when required.

qemu_cpu_kick_no_halt() moves and becomes qemu_cpu_kick_rr_cpu() to
emphasise its use-case. qemu_cpu_kick now kicks the relevant cpu as
well as qemu_kick_rr_cpu() which will become a no-op in MTTCG.

For the time being the setting of the global exit_request remains.

Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Reviewed-by: default avatarPranith Kumar <bobby.prani@gmail.com>
parent 6546706d

cpu-exec-common.c

+0 −1
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ 
#include "exec/memory-internal.h"



bool exit_request;

CPUState *tcg_current_cpu;



/* exit the current TB, but without causing any exception to be raised */

void cpu_loop_exit_noexc(CPUState *cpu)

cpu-exec.c

+0 −3
Original line number Diff line number Diff line
@@ -612,7 +612,6 @@ int cpu_exec(CPUState *cpu) 
        return EXCP_HALTED;

    }



    atomic_mb_set(&tcg_current_cpu, cpu);

    rcu_read_lock();



    if (unlikely(atomic_mb_read(&exit_request))) {
@@ -666,7 +665,5 @@ int cpu_exec(CPUState *cpu) 
    /* fail safe : never use current_cpu outside cpu_exec() */

    current_cpu = NULL;



    /* Does not need atomic_mb_set because a spurious wakeup is okay.  */

    atomic_set(&tcg_current_cpu, NULL);

    return ret;

}

cpus.c

+22 −19
Original line number Diff line number Diff line
@@ -780,8 +780,7 @@ void configure_icount(QemuOpts *opts, Error **errp) 
 */



static QEMUTimer *tcg_kick_vcpu_timer;



static void qemu_cpu_kick_no_halt(void);

static CPUState *tcg_current_rr_cpu;



#define TCG_KICK_PERIOD (NANOSECONDS_PER_SECOND / 10)
@@ -790,10 +789,23 @@ static inline int64_t qemu_tcg_next_kick(void) 
    return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + TCG_KICK_PERIOD;

}



/* Kick the currently round-robin scheduled vCPU */

static void qemu_cpu_kick_rr_cpu(void)

{

    CPUState *cpu;

    atomic_mb_set(&exit_request, 1);

    do {

        cpu = atomic_mb_read(&tcg_current_rr_cpu);

        if (cpu) {

            cpu_exit(cpu);

        }

    } while (cpu != atomic_mb_read(&tcg_current_rr_cpu));

}



static void kick_tcg_thread(void *opaque)

{

    timer_mod(tcg_kick_vcpu_timer, qemu_tcg_next_kick());

    qemu_cpu_kick_no_halt();

    qemu_cpu_kick_rr_cpu();

}



static void start_tcg_kick_timer(void)
@@ -813,7 +825,6 @@ static void stop_tcg_kick_timer(void) 
    }

}





/***********************************************************/

void hw_error(const char *fmt, ...)

{
@@ -1324,6 +1335,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) 
        }



        for (; cpu != NULL && !exit_request; cpu = CPU_NEXT(cpu)) {

            atomic_mb_set(&tcg_current_rr_cpu, cpu);



            qemu_clock_enable(QEMU_CLOCK_VIRTUAL,

                              (cpu->singlestep_enabled & SSTEP_NOTIMER) == 0);
@@ -1343,6 +1355,8 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) 
            }



        } /* for cpu.. */

        /* Does not need atomic_mb_set because a spurious wakeup is okay.  */

        atomic_set(&tcg_current_rr_cpu, NULL);



        /* Pairs with smp_wmb in qemu_cpu_kick.  */

        atomic_mb_set(&exit_request, 0);
@@ -1421,24 +1435,13 @@ static void qemu_cpu_kick_thread(CPUState *cpu) 
#endif

}



static void qemu_cpu_kick_no_halt(void)

{

    CPUState *cpu;

    /* Ensure whatever caused the exit has reached the CPU threads before

     * writing exit_request.

     */

    atomic_mb_set(&exit_request, 1);

    cpu = atomic_mb_read(&tcg_current_cpu);

    if (cpu) {

        cpu_exit(cpu);

    }

}



void qemu_cpu_kick(CPUState *cpu)

{

    qemu_cond_broadcast(cpu->halt_cond);

    if (tcg_enabled()) {

        qemu_cpu_kick_no_halt();

        cpu_exit(cpu);

        /* Also ensure current RR cpu is kicked */

        qemu_cpu_kick_rr_cpu();

    } else {

        if (hax_enabled()) {

            /*
@@ -1486,7 +1489,7 @@ void qemu_mutex_lock_iothread(void) 
        atomic_dec(&iothread_requesting_mutex);

    } else {

        if (qemu_mutex_trylock(&qemu_global_mutex)) {

            qemu_cpu_kick_no_halt();

            qemu_cpu_kick_rr_cpu();

            qemu_mutex_lock(&qemu_global_mutex);

        }

        atomic_dec(&iothread_requesting_mutex);

include/exec/exec-all.h

+0 −1
Original line number Diff line number Diff line
@@ -405,7 +405,6 @@ bool memory_region_is_unassigned(MemoryRegion *mr); 
extern int singlestep;



/* cpu-exec.c, accessed with atomic_mb_read/atomic_mb_set */

extern CPUState *tcg_current_cpu;

extern bool exit_request;



#endif