From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51589) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eOQsb-0004fe-Bb for qemu-devel@nongnu.org; Mon, 11 Dec 2017 11:24:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eOQsY-00046C-3a for qemu-devel@nongnu.org; Mon, 11 Dec 2017 11:24:33 -0500 References: <20171129191215.11323-1-david@redhat.com> From: Paolo Bonzini Message-ID: <3f0c7605-4090-c1f6-c40d-06aab9a3e992@redhat.com> Date: Mon, 11 Dec 2017 17:24:20 +0100 MIME-Version: 1.0 In-Reply-To: <20171129191215.11323-1-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v1] cpus: make pause_all_cpus() play with SMP on single threaded TCG List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand , qemu-s390x@nongnu.org, qemu-devel@nongnu.org Cc: Peter Crosthwaite , Christian Borntraeger , Cornelia Huck , Richard Henderson , Alexander Graf On 29/11/2017 20:12, David Hildenbrand wrote: > 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: David Hildenbrand > --- > cpus.c | 32 +++++++++++++++++++------------- > 1 file changed, 19 insertions(+), 13 deletions(-) > > diff --git a/cpus.c b/cpus.c > index 114c29b6a0..3740c4db62 100644 > --- a/cpus.c > +++ b/cpus.c > @@ -1057,13 +1057,22 @@ static void qemu_tcg_destroy_vcpu(CPUState *cpu) > { > } > > +static void qemu_cpu_stop(CPUState *cpu, bool exit) > +{ > + 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) { > - cpu->stop = false; > - cpu->stopped = true; > - qemu_cond_broadcast(&qemu_pause_cond); > + 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) { > - cpu->stop = true; > - qemu_cpu_kick(cpu); > - } > - > - if (qemu_in_vcpu_thread()) { > - cpu_stop_current(); > + if (qemu_cpu_is_self(cpu)) { > + qemu_cpu_stop(cpu, true); > + } else { > + cpu->stop = true; > + qemu_cpu_kick(cpu); > + } > } > > 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); > } > } This function is not needed anymore, because vm_stop can just call qemu_cpu_stop. Does the following squash look fine to you? diff --git a/cpus.c b/cpus.c index 83700c1716..a65591c183 100644 --- a/cpus.c +++ b/cpus.c @@ -1057,14 +1057,11 @@ static void qemu_tcg_destroy_vcpu(CPUState *cpu) { } -static void qemu_cpu_stop(CPUState *cpu, bool exit) +static void qemu_cpu_stop(CPUState *cpu) { g_assert(qemu_cpu_is_self(cpu)); cpu->stop = false; cpu->stopped = true; - if (exit) { - cpu_exit(cpu); - } qemu_cond_broadcast(&qemu_pause_cond); } @@ -1072,7 +1069,7 @@ static void qemu_wait_io_event_common(CPUState *cpu) { atomic_mb_set(&cpu->thread_kicked, false); if (cpu->stop) { - qemu_cpu_stop(cpu, false); + qemu_cpu_stop(cpu); } process_queued_cpu_work(cpu); } @@ -1620,7 +1617,8 @@ 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); + qemu_cpu_stop(cpu); + cpu_exit(cpu); } else { cpu->stop = true; qemu_cpu_kick(cpu); @@ -1802,13 +1800,6 @@ void qemu_init_vcpu(CPUState *cpu) } } -void cpu_stop_current(void) -{ - if (current_cpu) { - qemu_cpu_stop(current_cpu, true); - } -} - int vm_stop(RunState state) { if (qemu_in_vcpu_thread()) { @@ -1818,7 +1809,8 @@ int vm_stop(RunState state) * FIXME: should not return to device code in case * vm_stop() has been requested. */ - cpu_stop_current(); + qemu_cpu_stop(current_cpu); + cpu_exit(current_cpu); return 0; }