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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 31110C0650E for ; Wed, 3 Jul 2019 18:32:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A62721882 for ; Wed, 3 Jul 2019 18:32:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727261AbfGCScK (ORCPT ); Wed, 3 Jul 2019 14:32:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54056 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725933AbfGCScK (ORCPT ); Wed, 3 Jul 2019 14:32:10 -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 B5D31307D846; Wed, 3 Jul 2019 18:32:04 +0000 (UTC) Received: from x1.home (ovpn-116-83.phx2.redhat.com [10.3.116.83]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1818F83085; Wed, 3 Jul 2019 18:31:58 +0000 (UTC) Date: Wed, 3 Jul 2019 12:31:57 -0600 From: Alex Williamson To: Tiwei Bie Cc: mst@redhat.com, jasowang@redhat.com, maxime.coquelin@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, dan.daly@intel.com, cunming.liang@intel.com, zhihong.wang@intel.com Subject: Re: [RFC v2] vhost: introduce mdev based hardware vhost backend Message-ID: <20190703123157.2452bf95@x1.home> In-Reply-To: <20190703091339.1847-1-tiwei.bie@intel.com> References: <20190703091339.1847-1-tiwei.bie@intel.com> Organization: Red Hat 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 [10.5.110.48]); Wed, 03 Jul 2019 18:32:09 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 3 Jul 2019 17:13:39 +0800 Tiwei Bie wrote: > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index 8f10748dac79..6c5718ab7eeb 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -201,6 +201,7 @@ struct vfio_device_info { > #define VFIO_DEVICE_FLAGS_AMBA (1 << 3) /* vfio-amba device */ > #define VFIO_DEVICE_FLAGS_CCW (1 << 4) /* vfio-ccw device */ > #define VFIO_DEVICE_FLAGS_AP (1 << 5) /* vfio-ap device */ > +#define VFIO_DEVICE_FLAGS_VHOST (1 << 6) /* vfio-vhost device */ > __u32 num_regions; /* Max region index + 1 */ > __u32 num_irqs; /* Max IRQ index + 1 */ > }; > @@ -217,6 +218,7 @@ struct vfio_device_info { > #define VFIO_DEVICE_API_AMBA_STRING "vfio-amba" > #define VFIO_DEVICE_API_CCW_STRING "vfio-ccw" > #define VFIO_DEVICE_API_AP_STRING "vfio-ap" > +#define VFIO_DEVICE_API_VHOST_STRING "vfio-vhost" > > /** > * VFIO_DEVICE_GET_REGION_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 8, > @@ -573,6 +575,23 @@ enum { > VFIO_CCW_NUM_IRQS > }; > > +/* > + * The vfio-vhost bus driver makes use of the following fixed region and > + * IRQ index mapping. Unimplemented regions return a size of zero. > + * Unimplemented IRQ types return a count of zero. > + */ > + > +enum { > + VFIO_VHOST_CONFIG_REGION_INDEX, > + VFIO_VHOST_NOTIFY_REGION_INDEX, > + VFIO_VHOST_NUM_REGIONS > +}; > + > +enum { > + VFIO_VHOST_VQ_IRQ_INDEX, > + VFIO_VHOST_NUM_IRQS > +}; > + Note that the vfio API has evolved a bit since vfio-pci started this way, with fixed indexes for pre-defined region types. We now support device specific regions which can be identified by a capability within the REGION_INFO ioctl return data. This allows a bit more flexibility, at the cost of complexity, but the infrastructure already exists in kernel and QEMU to make it relatively easy. I think we'll have the same support for interrupts soon too. If you continue to pursue the vfio-vhost direction you might want to consider these before committing to fixed indexes. Thanks, Alex