From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH v3] kvm: make vcpu life cycle separated from kvm instance Date: Thu, 15 Dec 2011 11:08:16 +0200 Message-ID: <20111215090816.GA25517@redhat.com> References: <20111209142303.GC31323@redhat.com> <1323657683-13934-1-git-send-email-kernelfans@gmail.com> <20111213113628.GB31138@amt.cnet> <20111215083325.GA21664@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Marcelo Tosatti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, avi@redhat.com, aliguori@us.ibm.com, jan.kiszka@web.de To: Liu ping fan Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, Dec 15, 2011 at 05:06:09PM +0800, Liu ping fan wrote: > 2011/12/15 Gleb Natapov : > > 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 destro= yed. > >> >> 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 > >> >> --- > >> >> =9Aarch/x86/kvm/i8254.c =9A =9A | =9A 10 ++++-- > >> >> =9Aarch/x86/kvm/i8259.c =9A =9A | =9A 12 +++++-- > >> >> =9Aarch/x86/kvm/mmu.c =9A =9A =9A | =9A =9A7 ++-- > >> >> =9Aarch/x86/kvm/x86.c =9A =9A =9A | =9A 54 +++++++++++++++++++-= --------------- > >> >> =9Ainclude/linux/kvm_host.h | =9A 71 ++++++++++++++++++++++++++= ++++++++++++++++---- > >> >> =9Avirt/kvm/irq_comm.c =9A =9A =9A| =9A =9A7 +++- > >> >> =9Avirt/kvm/kvm_main.c =9A =9A =9A| =9A 62 ++++++++++++++++++++= +++++++++++++------ > >> >> =9A7 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 destroy= ed > >> before vcpu, so =9Ait 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. =9AAm I r= ight? > >> > >> As to the scene like bsp_vcpu, I think that introducing refcount l= ike > >> 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 introd= ucing > > reference count to keep the pointer valid is not necessary. The cou= nter > > will never reach 0 and bsp vcpu will never be freed. Just disallow >=20 > OK. And I have a question -- who will play the role to guard bsp_vcpu= ? > kernel or qemu? Must I add something in kernel to protect the > bsp_vcpu >=20 Kernel of course. But I prefer just to rid of bsp_vcpu. I'll try to sen= d patch today. > > removal of bsp_vcpu. Or better get rid of bsp_vcpu at all since its= only > > use is invalid anyway. > > > I will dig into it and see how to handle it. >=20 > Thanks and regards, > ping fan > > -- > > =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9A =9AGleb. -- Gleb.