From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [GIT PULL] First batch of KVM changes for 4.1 Date: Thu, 23 Apr 2015 13:29:28 +0200 Message-ID: <5538D798.1090509@redhat.com> References: <20150417105506.GF5029@twins.programming.kicks-ass.net> <553100C1.5000408@redhat.com> <20150417131037.GG23123@twins.programming.kicks-ass.net> <55310CF2.6070107@redhat.com> <20150417190146.GA24395@amt.cnet> <55316598.908@redhat.com> <20150417201841.GA31302@amt.cnet> <55353058.2000008@redhat.com> <20150422205602.GA15317@amt.cnet> <55380C3D.2080906@redhat.com> <20150422225559.GA21667@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: Peter Zijlstra , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, gleb@kernel.org, kvm@vger.kernel.org, Ralf Baechle , luto@kernel.org To: Marcelo Tosatti Return-path: Received: from mail-wi0-f175.google.com ([209.85.212.175]:34046 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934020AbbDWL3f (ORCPT ); Thu, 23 Apr 2015 07:29:35 -0400 In-Reply-To: <20150422225559.GA21667@amt.cnet> Sender: kvm-owner@vger.kernel.org List-ID: On 23/04/2015 00:55, Marcelo Tosatti wrote: > On Wed, Apr 22, 2015 at 11:01:49PM +0200, Paolo Bonzini wrote: >> >> >> On 22/04/2015 22:56, Marcelo Tosatti wrote: >>>>> But then why was the task migration notifier even in Jeremy's original >>>>> code for Xen? >>> To cover for the vcpu1 -> vcpu2 -> vcpu1 case, i believe. >> >> Ok, to cover it for non-synchronized TSC. While KVM requires >> synchronized TSC. >> >>>> If that's the case, then it could be reverted indeed; but then why did >>>> you commit this patch to 4.1? >>> >>> Because it fixes the problem Andy reported (see Subject: KVM: x86: fix >>> kvmclock write race (v2) on kvm@). As long as you have Radim's >>> fix on top. >> >> But if it's so rare, and it was known that fixing the host protocol was >> just as good a solution, why was the guest fix committed? > > I don't know. Should have fixed the host protocol. No problem. Let's do the right thing now. >> I'm just trying to understand. I am worried that this patch was rushed >> in; so far I had assumed it wasn't (a revert of a revert is rare enough >> that you don't do it lightly...) but maybe I was wrong. > > Yes it was rushed in. Ok, so re-reverted it will be. Paolo