From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932410Ab1LOIdb (ORCPT ); Thu, 15 Dec 2011 03:33:31 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39353 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757339Ab1LOId3 convert rfc822-to-8bit (ORCPT ); Thu, 15 Dec 2011 03:33:29 -0500 Date: Thu, 15 Dec 2011 10:33:25 +0200 From: Gleb Natapov To: Liu ping fan Cc: Marcelo Tosatti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, avi@redhat.com, aliguori@us.ibm.com, jan.kiszka@web.de Subject: Re: [PATCH v3] kvm: make vcpu life cycle separated from kvm instance Message-ID: <20111215083325.GA21664@redhat.com> References: <20111209142303.GC31323@redhat.com> <1323657683-13934-1-git-send-email-kernelfans@gmail.com> <20111213113628.GB31138@amt.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 15, 2011 at 11:21:37AM +0800, Liu ping fan wrote: > On Tue, Dec 13, 2011 at 7:36 PM, Marcelo Tosatti wrote: > > On Mon, Dec 12, 2011 at 10:41:23AM +0800, Liu Ping Fan wrote: > >> From: Liu Ping Fan > >> > >> Currently, vcpu can be destructed only when kvm instance destroyed. > >> Change this to vcpu's destruction taken when its refcnt is zero, > >> and then vcpu MUST and CAN be destroyed before kvm's destroy. > >> > >> Signed-off-by: Liu Ping Fan > >> --- > >> šarch/x86/kvm/i8254.c š š | š 10 ++++-- > >> šarch/x86/kvm/i8259.c š š | š 12 +++++-- > >> šarch/x86/kvm/mmu.c š š š | š š7 ++-- > >> šarch/x86/kvm/x86.c š š š | š 54 +++++++++++++++++++---------------- > >> šinclude/linux/kvm_host.h | š 71 ++++++++++++++++++++++++++++++++++++++++++---- > >> švirt/kvm/irq_comm.c š š š| š š7 +++- > >> švirt/kvm/kvm_main.c š š š| š 62 +++++++++++++++++++++++++++++++++------ > >> š7 files changed, 170 insertions(+), 53 deletions(-) > > > > This needs a full audit of paths that access vcpus. See for one example > > bsp_vcpu pointer. > > > Yes, I had missed it and just paid attention to the access path to > vcpu in kvm_lapic and the path used in async_pf. I will correct it > later. > BTW, I want to make it sure that because kvm_lapic will be destroyed > before vcpu, so it is safe to bypass the access path there, and the > situation is the same in async_pf for we have called > kvm_clear_async_pf_completion_queue before zapping vcpu. Am I right? > > As to the scene like bsp_vcpu, I think that introducing refcount like > in V2 can handle it easier. Please help to review these changes in V4 > which I will send a little later. > Since bsp_vcpu pointer will never be released or re-assigned introducing reference count to keep the pointer valid is not necessary. The counter will never reach 0 and bsp vcpu will never be freed. Just disallow removal of bsp_vcpu. Or better get rid of bsp_vcpu at all since its only use is invalid anyway. -- Gleb.