From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39146) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fXQ4Q-0007dQ-E7 for qemu-devel@nongnu.org; Mon, 25 Jun 2018 07:54:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fXQ4P-0001yz-Nl for qemu-devel@nongnu.org; Mon, 25 Jun 2018 07:54:10 -0400 From: David Hildenbrand Date: Mon, 25 Jun 2018 13:53:52 +0200 Message-Id: <20180625115352.6889-10-david@redhat.com> In-Reply-To: <20180625115352.6889-1-david@redhat.com> References: <20180625115352.6889-1-david@redhat.com> Subject: [Qemu-devel] [PATCH v3 9/9] s390x/tcg: fix CPU hotplug with single-threaded TCG List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-s390x@nongnu.org Cc: qemu-devel@nongnu.org, Richard Henderson , Alexander Graf , Cornelia Huck , Christian Borntraeger , Thomas Huth , David Hildenbrand run_on_cpu() doesn't seem to work reliably until the CPU has been fully created if the single-threaded TCG main loop is already running. Therefore, hotplugging a CPU under single-threaded TCG does currently not work. We should use the direct call instead of going via run_on_cpu(). So let's use run_on_cpu() for KVM only - KVM requires it due to the initial CPU reset ioctl. As a nice side effect, we get rif of the ifdef. Signed-off-by: David Hildenbrand --- target/s390x/cpu.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c index 40d6980229..271c5ce652 100644 --- a/target/s390x/cpu.c +++ b/target/s390x/cpu.c @@ -218,11 +218,18 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp) #endif s390_cpu_gdb_init(cs); qemu_init_vcpu(cs); -#if !defined(CONFIG_USER_ONLY) - run_on_cpu(cs, s390_do_cpu_full_reset, RUN_ON_CPU_NULL); -#else - cpu_reset(cs); -#endif + + /* + * KVM requires the initial CPU reset ioctl to be executed on the target + * CPU thread. CPU hotplug under single-threaded TCG will not work with + * run_on_cpu(), as run_on_cpu() will not work properly if called while + * the main thread is already running but the CPU hasn't been realized. + */ + if (kvm_enabled()) { + run_on_cpu(cs, s390_do_cpu_full_reset, RUN_ON_CPU_NULL); + } else { + cpu_reset(cs); + } scc->parent_realize(dev, &err); out: -- 2.17.1