From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1379FC7618B for ; Tue, 23 Jul 2019 12:14:20 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DF1F8218B8 for ; Tue, 23 Jul 2019 12:14:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DF1F8218B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42002 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hptgR-0005iJ-5g for qemu-devel@archiver.kernel.org; Tue, 23 Jul 2019 08:14:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37587) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hptgH-0005Je-LZ for qemu-devel@nongnu.org; Tue, 23 Jul 2019 08:14:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hptgG-0007EG-Ky for qemu-devel@nongnu.org; Tue, 23 Jul 2019 08:14:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36048) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hptgG-00079g-Cc for qemu-devel@nongnu.org; Tue, 23 Jul 2019 08:14:08 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 57B5F81F11; Tue, 23 Jul 2019 12:14:06 +0000 (UTC) Received: from gondolin (dhcp-192-181.str.redhat.com [10.33.192.181]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3AC0C5B684; Tue, 23 Jul 2019 12:13:59 +0000 (UTC) Date: Tue, 23 Jul 2019 14:13:57 +0200 From: Cornelia Huck To: Alex Williamson Message-ID: <20190723141357.7b10c4f2.cohuck@redhat.com> In-Reply-To: <20190716145632.3b73b73d@x1.home> References: <1562665760-26158-1-git-send-email-kwankhede@nvidia.com> <1562665760-26158-2-git-send-email-kwankhede@nvidia.com> <20190716145632.3b73b73d@x1.home> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 23 Jul 2019 12:14:06 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v7 01/13] vfio: KABI for migration interface X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kevin.tian@intel.com, yi.l.liu@intel.com, cjia@nvidia.com, eskultet@redhat.com, ziye.yang@intel.com, qemu-devel@nongnu.org, Zhengxiao.zx@Alibaba-inc.com, shuangtai.tst@alibaba-inc.com, dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, Kirti Wankhede , eauger@redhat.com, felipe@nutanix.com, jonathan.davies@nutanix.com, yan.y.zhao@intel.com, changpeng.liu@intel.com, Ken.Xue@amd.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 16 Jul 2019 14:56:32 -0600 Alex Williamson wrote: > On Tue, 9 Jul 2019 15:19:08 +0530 > Kirti Wankhede wrote: I'm still a bit unsure about the device_state bit handling as well. > > + * device_state: (read/write) > > + * To indicate vendor driver the state VFIO device should be transitioned > > + * to. If device state transition fails, write on this field return error. Does 'device state transition fails' include 'the device state written was invalid'? > > + * It consists of 3 bits: > > + * - If bit 0 set, indicates _RUNNING state. When its reset, that indicates > > + * _STOPPED state. When device is changed to _STOPPED, driver should stop > > + * device before write() returns. So _STOPPED is always !_RUNNING, regardless of which other bits are set? > > + * - If bit 1 set, indicates _SAVING state. > > + * - If bit 2 set, indicates _RESUMING state. > > + * _SAVING and _RESUMING set at the same time is invalid state. What about _RUNNING | _RESUMING -- does that make sense? > > I think in the previous version there was a question of how we handle > yet-to-be-defined bits. For instance, if we defined a > SUBTYPE_MIGRATIONv2 with the intention of making it backwards > compatible with this version, do we declare the undefined bits as > preserved so that the user should do a read-modify-write operation? Or can we state that undefined bits are ignored, and may or may not preserved, so that we can skip the read-modify-write requirement? v1 and v2 can hopefully be distinguished in a different way. (...) > > +struct vfio_device_migration_info { > > + __u32 device_state; /* VFIO device state */ > > +#define VFIO_DEVICE_STATE_RUNNING (1 << 0) > > +#define VFIO_DEVICE_STATE_SAVING (1 << 1) > > +#define VFIO_DEVICE_STATE_RESUMING (1 << 2) > > +#define VFIO_DEVICE_STATE_MASK (VFIO_DEVICE_STATE_RUNNING | \ > > + VFIO_DEVICE_STATE_SAVING | \ > > + VFIO_DEVICE_STATE_RESUMING) > > Yes, we have the mask in here now, but no mention above how the user > should handle undefined bits. Thanks, > > Alex > > > +#define VFIO_DEVICE_STATE_INVALID (VFIO_DEVICE_STATE_SAVING | \ > > + VFIO_DEVICE_STATE_RESUMING) As mentioned above, does _RESUMING | _RUNNING make sense?