From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752414Ab1LIK7W (ORCPT ); Fri, 9 Dec 2011 05:59:22 -0500 Received: from e23smtp02.au.ibm.com ([202.81.31.144]:40429 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751464Ab1LIK7U (ORCPT ); Fri, 9 Dec 2011 05:59:20 -0500 Message-ID: <4EE1E9FA.5030307@linux.vnet.ibm.com> Date: Fri, 09 Dec 2011 16:29:06 +0530 From: Raghavendra K T User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.24) Gecko/20111108 Fedora/3.1.16-1.fc14 Thunderbird/3.1.16 MIME-Version: 1.0 To: Avi Kivity CC: Marcelo Tosatti , Raghavendra K T , Greg Kroah-Hartman , KVM , Konrad Rzeszutek Wilk , Sedat Dilek , Virtualization , Jeremy Fitzhardinge , x86@kernel.org, "H. Peter Anvin" , Dave Jiang , Thomas Gleixner , Stefano Stabellini , Gleb Natapov , Yinghai Lu , Ingo Molnar , Rik van Riel , Xen , LKML , Srivatsa Vaddagiri , Peter Zijlstra , Sasha Levin , Suzuki Poulose , Dave Hansen , Jeremy Fitzhardinge Subject: Re: [PATCH RFC V3 2/4] kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks References: <20111130085921.23386.89708.sendpatchset@oc5400248562.ibm.com> <20111130085959.23386.69166.sendpatchset@oc5400248562.ibm.com> <20111207104849.GA24849@amt.cnet> <4EDF5413.1030107@linux.vnet.ibm.com> <20111207123330.GA32212@amt.cnet> <4EDF6049.2030204@redhat.com> <20111207133947.GA1708@amt.cnet> <4EDF7DC5.5010504@redhat.com> <4EDF987B.8040900@linux.vnet.ibm.com> <4EE08606.2060508@redhat.com> In-Reply-To: <4EE08606.2060508@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit x-cbid: 11120900-5490-0000-0000-0000004E61D3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/08/2011 03:10 PM, Avi Kivity wrote: > On 12/07/2011 06:46 PM, Raghavendra K T wrote: >> On 12/07/2011 08:22 PM, Avi Kivity wrote: >>> On 12/07/2011 03:39 PM, Marcelo Tosatti wrote: >>>>> Also I think we can keep the kicked flag in vcpu->requests, no need >>>>> for >>>>> new storage. >>>> >>>> Was going to suggest it but it violates the currently organized >>>> processing of entries at the beginning of vcpu_enter_guest. >>>> >>>> That is, this "kicked" flag is different enough from vcpu->requests >>>> processing that a separate variable seems worthwhile (even more >>>> different with convertion to MP_STATE at KVM_GET_MP_STATE). >>> >>> IMO, it's similar to KVM_REQ_EVENT (which can also cause mpstate to >>> change due to apic re-evaluation). >>> >> >> Ok, So what I understand is we have to either : >> 1. retain current kick flag AS-IS but would have to make it migration >> friendly. [I still have to get more familiar with migration side] >> or >> 2. introduce notion similar to KVM_REQ_PVLOCK_KICK(??) to be part of >> vcpu->requests. >> >> So what would be better? Please let me know. >> > > IMO, KVM_REQ. > Ok, 'll continue in this direction. Hmm I think now the race condition should be kept in mind, pointed by Marcello.