From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2 2/5] target-i386/kvm: Hyper-V SynIC MSR's support Date: Wed, 11 Nov 2015 10:17:18 +0100 Message-ID: <5643079E.8010908@redhat.com> References: <1447159964-22987-1-git-send-email-asmetanin@virtuozzo.com> <1447159964-22987-3-git-send-email-asmetanin@virtuozzo.com> <5641EDA2.6020707@redhat.com> <564305B4.9060907@virtuozzo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: "Denis V. Lunev" , Richard Henderson , Eduardo Habkost , =?UTF-8?Q?Andreas_F=c3=a4rber?= , Marcelo Tosatti , Roman Kagan , kvm@vger.kernel.org To: asmetanin@virtuozzo.com, qemu-devel@nongnu.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:49456 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082AbbKKJRZ (ORCPT ); Wed, 11 Nov 2015 04:17:25 -0500 In-Reply-To: <564305B4.9060907@virtuozzo.com> Sender: kvm-owner@vger.kernel.org List-ID: On 11/11/2015 10:09, Andrey Smetanin wrote: >> >> I would prefer to put this in kvm_arch_init_vcpu, if possible. >> > Ok. I think the kvm_arch_init_vcpu() is called after migration restores > cpu->env->msr_hv_synic_* values, so unconditional initialization of > cpu->env->msr_hv_synic_* values can overwrite migrated values. The check > "if (!env->msr_hv_synic_version) {" is neccessary for first time > initialization to protect against such overwriting. This is why this > code migrates 'msr_hv_synic_version' value. No, kvm_arch_init_vcpu is called at the very beginning, when the VCPU thread is created. main -> machine_class->init -> pc_init1 -> pc_cpus_init -> pc_new_cpu -> cpu_x86_create -> object_property_set_bool -> x86_cpu_realizefn -> qemu_init_vcpu -> qemu_kvm_start_vcpu -> qemu_kvm_cpu_thread_fn (in new thread) -> kvm_init_vcpu -> kvm_arch_init_vcpu This is long before qemu_start_incoming_migration, which is among the last things done before calling main_loop Paolo