From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-238414-1517513596-2-8402956060029064920 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no ("Email failed DMARC policy for domain") X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='com', MailFrom='org' X-Spam-charsets: to='UTF-8', plain='utf-8' X-IgnoreVacation: yes ("Email failed DMARC policy for domain") X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1517513596; b=Mx8iUhMmfyBhLvBTOr9CUxOms/2RWtxwkVm3YnWFRXmCxNE 725r1AxOkgv+4q03nk8qdzzKOLfbhIlCok37Rsg9BqKlzWaahoYqS8uvBJpznAUW bOFEOiBi4eXHVOGDZQsdTNFXeRubxKhuJPKCAL/REzesC7pxRbWjW6fBs+MNyLJn 1yfcagDhbIeXPqYgPElLKy70wLpncv2pszkXEBKeEjd2Y/1Qn4dgz4qNvEEvPLd5 IOWlw0pPEXWtwNE60itCK1bLJ6n2cB5jyoClC0iP9tFYYNJFLERfZ4Yw0E0K4Lat plcVSR8Cl1q3cbjXGX6apMv0Qs6aZaEc7kB2rpg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=subject:to:cc:references:from:message-id :date:mime-version:in-reply-to:content-type :content-transfer-encoding:sender:list-id; s=arctest; t= 1517513596; bh=lUrIRD0kg0G/IVmMRlHmhr2vr9g3nn9gdBAmAnsxKBU=; b=I 0PV+Ms2SEDLAc+ia/S046ujZTYmJfuf+ZMl/eHoZyzRsk2Z3ZJasBpNiR1Dt/oxJ yFGQx28whp+yElCnpRS7eGJWWtp0QUh+p4h/GfHGwVhpkk/Be/wp0IDiY5ai7h1J mEcmXGn7A5o/BgDyRS7vbv6ZYZ3No71fydelLqwbcBcTWwcc4stSi9zqKwTuHFro QozV1HGYRa46PCLlK0sODRwXCH4fZ0ryZutcgTeEvSbPX09jt2AfXl0fLUR4ro/M G9KtSIXYjNO6Tn+V14Rn7Jg6zjo1oVuibW4Vel8Tl90xtK97KhqJaiQhESfwkg0L IygmNlCv8Eo7dAd0GA4YA== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754594AbeBATdO (ORCPT ); Thu, 1 Feb 2018 14:33:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40592 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754563AbeBATdO (ORCPT ); Thu, 1 Feb 2018 14:33:14 -0500 Subject: Re: [PATCH] KVM: x86: fix backward migration with async_PF To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Wanpeng Li , stable@vger.kernel.org References: <20180201175022.25011-1-rkrcmar@redhat.com> <20180201191040.GD26932@flask> From: Paolo Bonzini Message-ID: Date: Thu, 1 Feb 2018 14:33:10 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180201191040.GD26932@flask> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 01/02/2018 14:10, Radim Krčmář wrote: >>> >> This check will break migration if the source guest and host both have >> the recent kernels which support KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT, so >> I am not sure about it. Otherwise, the patch is okay! > Good point, breaking forward migration is worse than doing nothing. > > A compromise solution would be to drop the feature check from the > hypervisor. Newer guests would work everywhere and there would be no > change to old systems, so v4.13-v4.15 guests could at least upgrade. > > Slightly better than doing nothing, IMO, Yes, I agree. Just removing the guest_kvm_cpuid_has should be fine. Paolo