From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59582) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eFO6z-0007Dm-BE for qemu-devel@nongnu.org; Thu, 16 Nov 2017 12:38:02 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eFO6v-0001Q4-C6 for qemu-devel@nongnu.org; Thu, 16 Nov 2017 12:38:01 -0500 Received: from mail-wr0-x243.google.com ([2a00:1450:400c:c0c::243]:51815) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1eFO6v-0001NN-5r for qemu-devel@nongnu.org; Thu, 16 Nov 2017 12:37:57 -0500 Received: by mail-wr0-x243.google.com with SMTP id z14so4759375wrb.8 for ; Thu, 16 Nov 2017 09:37:56 -0800 (PST) References: <20171116170526.12643-1-david@redhat.com> <20171116170526.12643-3-david@redhat.com> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <20171116170526.12643-3-david@redhat.com> Date: Thu, 16 Nov 2017 17:37:54 +0000 Message-ID: <87375e15vx.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v1 for-2.11 2/3] s390x/tcg: fix DIAG 308 with > 1 VCPU (single threaded TCG) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand Cc: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Christian Borntraeger , Cornelia Huck , Alexander Graf , Richard Henderson David Hildenbrand writes: > Currently, single threaded TCG with > 1 VCPU gets stuck during IPL, when > the bios tries to switch to the loaded kernel via DIAG 308. > > pause_all_vcpus()/resume_all_vcpus() should not be called from a VCPU. > > And there is also no need for it. run_on_cpu() will make sure that the > CPUs exit KVM/TCG, where they get stopped. Once stopped, they will no > longer run. > > Signed-off-by: David Hildenbrand > --- > target/s390x/diag.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/target/s390x/diag.c b/target/s390x/diag.c > index dbbb9e886f..52bc348808 100644 > --- a/target/s390x/diag.c > +++ b/target/s390x/diag.c > @@ -27,7 +27,6 @@ static int modified_clear_reset(S390CPU *cpu) > S390CPUClass *scc =3D S390_CPU_GET_CLASS(cpu); > CPUState *t; > > - pause_all_vcpus(); > cpu_synchronize_all_states(); > CPU_FOREACH(t) { > run_on_cpu(t, s390_do_cpu_full_reset, RUN_ON_CPU_NULL); I think you also need to fix the run_on_cpu to be a async_run_on_cpu as you would otherwise hang waiting for run_on_cpu to finish on a single-threaded TCG run (as you are in the only vCPU context). If it is important that the source vCPU doesn't continue you can schedule it's work afterwards with a async_safe_run_on_cpu which will complete after all other vCPUs have executed their work. > @@ -37,7 +36,6 @@ static int modified_clear_reset(S390CPU *cpu) > s390_crypto_reset(); > scc->load_normal(CPU(cpu)); > cpu_synchronize_all_post_reset(); > - resume_all_vcpus(); > return 0; > } > > @@ -53,7 +51,6 @@ static int load_normal_reset(S390CPU *cpu) > S390CPUClass *scc =3D S390_CPU_GET_CLASS(cpu); > CPUState *t; > > - pause_all_vcpus(); > cpu_synchronize_all_states(); > CPU_FOREACH(t) { > run_on_cpu(t, s390_do_cpu_reset, RUN_ON_CPU_NULL); > @@ -63,7 +60,6 @@ static int load_normal_reset(S390CPU *cpu) > scc->initial_cpu_reset(CPU(cpu)); > scc->load_normal(CPU(cpu)); > cpu_synchronize_all_post_reset(); > - resume_all_vcpus(); > return 0; > } > > -- > 2.13.6 -- Alex Benn=C3=A9e