From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] x86: kvm: reset the bootstrap processor when it gets an INIT Date: Mon, 11 Mar 2013 11:14:39 +0100 Message-ID: <513DAE8F.3050102@redhat.com> References: <1362811713-25830-1-git-send-email-pbonzini@redhat.com> <20130310114646.GM11223@redhat.com> <513C9E82.1020304@redhat.com> <20130310153540.GL24444@redhat.com> <513CC08B.2040800@redhat.com> <20130310181035.GM24444@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mtosatti@redhat.com, jan.kiszka@siemens.com To: Gleb Natapov Return-path: In-Reply-To: <20130310181035.GM24444@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Il 10/03/2013 19:10, Gleb Natapov ha scritto: > On Sun, Mar 10, 2013 at 06:19:07PM +0100, Paolo Bonzini wrote: >> Il 10/03/2013 16:35, Gleb Natapov ha scritto: >>>>> However, it would effectively redefine the meaning of >>>>> KVM_MP_STATE_INIT_RECEIVED and KVM_MP_STATE_SIPI_RECEIVED, respectively >>>>> to KVM_MP_STATE_WAIT_FOR_SIPI and KVM_MP_STATE_RESETTING. I wasn't sure >>>>> if this is considered an API change (personally, I would treat it as one). >>>>> >>> If it is kernel module internal it definitely is not API change. >>> INIT/SIPI handling is a bit ad-hoc right now anyway as Jan noticed. For >>> instance INIT does not really resets VCPU. Only after SIPI it is really >>> reset, so KVM_MP_STATE_SIPI_RECEIVED is really KVM_MP_STATE_RESET_ME_RIGHT_NOW >>> state. >> >> Yeah, and the current definition is ambiguous (without hypervisor >> patches, there's no way to use it as the names would suggest), so >> perhaps the right thing to do is to rename the states (old names kept >> for backwards compatibility only) and work from there. >> > I do not see how renaming clarify things. From userspace point of view > KVM_MP_STATE_SIPI_RECEIVED does not exists. Not really true---we do exit with that state and EINTR when we get a SIPI. Perhaps that can be changed. > If AP is hard reset > userspase makes it UNINIT, if soft reset it makes it INIT_RECEIVED, if > BSP it makes it running no matter what type of reset. The current name just suggests . And when getting an INIT in the in-kernel LAPIC, this: - vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED; + vcpu->arch.mp_state = kvm_vcpu_is_bsp(vcpu) ? + KVM_MP_STATE_SIPI_RECEIVED : + KVM_MP_STATE_INIT_RECEIVED; makes much less sense than this: - vcpu->arch.mp_state = KVM_MP_STATE_WAIT_FOR_SIPI; + vcpu->arch.mp_state = kvm_vcpu_is_bsp(vcpu) ? + KVM_MP_STATE_RESET_NOW : + KVM_MP_STATE_WAIT_FOR_SIPI; However, there's also Jan's plans for nVMX. Peeking at his queue (see http://git.kiszka.org/?p=linux-kvm.git;a=commitdiff;h=037fb24ec) I think it's better to always reflect INITs to the hypervisor like I did in these patches. Paolo