From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH v8 00/11] KVM: MMU: fast zap all shadow pages Date: Sun, 9 Jun 2013 12:09:14 +0300 Message-ID: <20130609090914.GK4725@redhat.com> References: <1369960590-14138-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <20130609085342.GI4725@redhat.com> <51B44590.7030009@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: avi.kivity@gmail.com, mtosatti@redhat.com, pbonzini@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org To: Xiao Guangrong Return-path: Content-Disposition: inline In-Reply-To: <51B44590.7030009@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Sun, Jun 09, 2013 at 05:06:24PM +0800, Xiao Guangrong wrote: > On 06/09/2013 04:53 PM, Gleb Natapov wrote: > > On Fri, May 31, 2013 at 08:36:19AM +0800, Xiao Guangrong wrote: > >> Hi Gleb, Paolo, Marcelo, > >> > >> I have putted the potential controversial patches to the latter that are > >> patch 8 ~ 10, patch 11 depends on patch 9. Other patches are fully reviewed, > >> I think its are ready for being merged. If not luck enough, further discussion > >> is needed, could you please apply that patches first? :) > >> > >> Thank you in advance! > >> > >> Some points are raised during discussion but missed in this version: > >> 1) Gleb's idea that skip obsolete pages in the hast list walker > >> > >> Unfortunately, it is not safe. There has a window between updating > >> valid-gen and reloading mmu, in that window, the obsolete page can > >> be used by vcpu, but the guest page table fail to be write-protected > >> (since the obsolete page is skipped in mmu_need_write_protect()). > >> > > Can you elaborate on how this can happen. valid_gen is updated under > > mmu_lock and reloading of mmus happens under the same lock, so for all > > other vcpus this should look like atomic thing. > > You're right. > > Actually, i made another optimization patch in this version that moves > kvm_reload_remote_mmus() out of mmu-lock, but did not attach it into this > series. It seems my brain is not parallel-able enough. :( Yours is the most parallel-able I ever saw :) -- Gleb.