Commit ebd05fea authored by David Hildenbrand's avatar David Hildenbrand Committed by Paolo Bonzini
Browse files

cpus: make pause_all_cpus() play with SMP on single threaded TCG 



pause_all_cpus() is sometimes called from a VCPU thread (e.g. s390x
during special reset). It cannot deal with multiple VCPUs per Thread
(single threaded TCG) yet.

Booting an s390x guest with -smp 2 and single threaded TCG from disk
currently fails. The DIAG 308 will issue a pause_all_cpus() and wait
forever for the CPUs to actually stop. But it is waiting for itself.

So let's stop all VCPUs belonging to the current thread. Factor out
stopping of a VCPU.

Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Message-Id: <20171129191215.11323-1-david@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 09df29b6

cpus.c

+19 −13
Original line number Diff line number Diff line
@@ -1057,14 +1057,23 @@ static void qemu_tcg_destroy_vcpu(CPUState *cpu) 
{

}



static void qemu_wait_io_event_common(CPUState *cpu)

static void qemu_cpu_stop(CPUState *cpu, bool exit)

{

    atomic_mb_set(&cpu->thread_kicked, false);

    if (cpu->stop) {

    g_assert(qemu_cpu_is_self(cpu));

    cpu->stop = false;

    cpu->stopped = true;

    if (exit) {

        cpu_exit(cpu);

    }

    qemu_cond_broadcast(&qemu_pause_cond);

}



static void qemu_wait_io_event_common(CPUState *cpu)

{

    atomic_mb_set(&cpu->thread_kicked, false);

    if (cpu->stop) {

        qemu_cpu_stop(cpu, false);

    }

    process_queued_cpu_work(cpu);

}
@@ -1610,12 +1619,12 @@ void pause_all_vcpus(void) 


    qemu_clock_enable(QEMU_CLOCK_VIRTUAL, false);

    CPU_FOREACH(cpu) {

        if (qemu_cpu_is_self(cpu)) {

            qemu_cpu_stop(cpu, true);

        } else {

            cpu->stop = true;

            qemu_cpu_kick(cpu);

        }



    if (qemu_in_vcpu_thread()) {

        cpu_stop_current();

    }



    while (!all_vcpus_paused()) {
@@ -1799,10 +1808,7 @@ void qemu_init_vcpu(CPUState *cpu) 
void cpu_stop_current(void)

{

    if (current_cpu) {

        current_cpu->stop = false;

        current_cpu->stopped = true;

        cpu_exit(current_cpu);

        qemu_cond_broadcast(&qemu_pause_cond);

        qemu_cpu_stop(current_cpu, true);

    }

}