From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 1/2] KVM: x86 emulator: don't update vcpu state if instruction is restarted. Date: Mon, 02 Aug 2010 08:04:20 +0300 Message-ID: <4C5651D4.7060905@redhat.com> References: <20100801082815.GC24773@redhat.com> <4C55364E.9090605@redhat.com> <20100801090145.GD24773@redhat.com> <4C553B00.8030100@redhat.com> <20100801092438.GE24773@redhat.com> <4C5545AB.3080806@redhat.com> <20100801105337.GF24773@redhat.com> <4C5565C6.1090004@redhat.com> <20100801122316.GG24773@redhat.com> <4C556A1D.2050105@redhat.com> <20100801132714.GH24773@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: mtosatti@redhat.com, kvm@vger.kernel.org To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43504 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752543Ab0HBFEY (ORCPT ); Mon, 2 Aug 2010 01:04:24 -0400 Received: from int-mx03.intmail.prod.int.phx2.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o7254OC1014548 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 2 Aug 2010 01:04:24 -0400 In-Reply-To: <20100801132714.GH24773@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/01/2010 04:27 PM, Gleb Natapov wrote: > > When we are going to enable e_i_g_s by default? Optimistically, 2.6.37, so six months. > May be we have enough > time to fix userspace? Sure we do, but will users update? 0.12 is mature enough that some users will forget about it and not update it. > Too ancient userspace already does not run on recent > kvm. Or may be we can make userspace enable e_i_g_s per guest. This way > userspace that knows it is OK can tell kernel so. Let's make it the other way round, enable the optimization for userspace that declares that it does not make use of rip during emulation (kvm-tpr-opt can be changed by queueing a signal and re-entering the guest to complete the operation). Later we can make the optimization unconditional. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.