From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45831) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bFyCn-0004SH-If for qemu-devel@nongnu.org; Thu, 23 Jun 2016 02:33:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bFyCi-00056L-H0 for qemu-devel@nongnu.org; Thu, 23 Jun 2016 02:33:37 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:10563 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bFyCi-00056H-B0 for qemu-devel@nongnu.org; Thu, 23 Jun 2016 02:33:32 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u5N6TuJg064213 for ; Thu, 23 Jun 2016 02:33:31 -0400 Received: from e06smtp16.uk.ibm.com (e06smtp16.uk.ibm.com [195.75.94.112]) by mx0b-001b2d01.pphosted.com with ESMTP id 23q703uk3j-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 23 Jun 2016 02:33:31 -0400 Received: from localhost by e06smtp16.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 23 Jun 2016 07:33:27 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 5CDB02190056 for ; Thu, 23 Jun 2016 07:32:54 +0100 (BST) Received: from d06av03.portsmouth.uk.ibm.com (d06av03.portsmouth.uk.ibm.com [9.149.37.213]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u5N6XNVe5701904 for ; Thu, 23 Jun 2016 06:33:23 GMT Received: from d06av03.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av03.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u5N6XMDw011556 for ; Thu, 23 Jun 2016 00:33:23 -0600 Date: Thu, 23 Jun 2016 08:33:21 +0200 From: David Hildenbrand In-Reply-To: <20160622182119.GO2048@thinpad.lan.raisama.net> References: <1466514153-85777-1-git-send-email-dahi@linux.vnet.ibm.com> <20160621164431.GI2048@thinpad.lan.raisama.net> <20160621205628.GA571189@orkuz.home> <20160622182119.GO2048@thinpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Message-Id: <20160623083321.54bfa31f@thinkpad-w530> Subject: Re: [Qemu-devel] [RFC 00/28] s390x CPU models: exposing features List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: qemu-devel@nongnu.org, imammedo@redhat.com, cornelia.huck@de.ibm.com, borntraeger@de.ibm.com, fiuczy@linux.vnet.ibm.com, mimu@linux.vnet.ibm.com, libvir-list@redhat.com > Question: KVM supports x2apic (and enables it by default) on any > host CPU, because it is all emulated by KVM. Should "host-model" > include x2apic on all hosts, or only when the host CPU has it? > ("-cpu host" does include it). >=20 > Including x2apic sounds more useful, but it doesn't match the > "get as close to the host CPU as possible" part of your > description. >=20 =46rom a s390x point of view, our "host" model is about indicating the maximum possible configuration we are able to virtualize, not strictly limiting it = only to the real host features. We also have a feature called "sthyi", emulated by KVM, which might not be around for the real "host". We will include that in "host", because otherwi= se things seem to get really complicated with no obvious benefit (to me :) ). Not sure how you want to handle that. David