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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 F03B4C3A5A6 for ; Fri, 20 Sep 2019 01:31:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CEB72206C2 for ; Fri, 20 Sep 2019 01:31:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394601AbfITBbV (ORCPT ); Thu, 19 Sep 2019 21:31:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36790 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391404AbfITBbU (ORCPT ); Thu, 19 Sep 2019 21:31:20 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CA48B308FB9D; Fri, 20 Sep 2019 01:31:19 +0000 (UTC) Received: from [10.72.12.88] (ovpn-12-88.pek2.redhat.com [10.72.12.88]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5392F100197A; Fri, 20 Sep 2019 01:31:00 +0000 (UTC) Subject: Re: [RFC v4 0/3] vhost: introduce mdev based hardware backend To: Tiwei Bie Cc: "Michael S. Tsirkin" , alex.williamson@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, lingshan.zhu@intel.com References: <20190917010204.30376-1-tiwei.bie@intel.com> <993841ed-942e-c90b-8016-8e7dc76bf13a@redhat.com> <20190917105801.GA24855@___> <20190918102923-mutt-send-email-mst@kernel.org> <20190919154552.GA27657@___> From: Jason Wang Message-ID: <43aaf7dc-f08b-8898-3c55-908ff4d68866@redhat.com> Date: Fri, 20 Sep 2019 09:30:58 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190919154552.GA27657@___> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Fri, 20 Sep 2019 01:31:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/9/19 下午11:45, Tiwei Bie wrote: > On Thu, Sep 19, 2019 at 09:08:11PM +0800, Jason Wang wrote: >> On 2019/9/18 下午10:32, Michael S. Tsirkin wrote: >>>>>> So I have some questions: >>>>>> >>>>>> 1) Compared to method 2, what's the advantage of creating a new vhost char >>>>>> device? I guess it's for keep the API compatibility? >>>>> One benefit is that we can avoid doing vhost ioctls on >>>>> VFIO device fd. >>>> Yes, but any benefit from doing this? >>> It does seem a bit more modular, but it's certainly not a big deal. >> Ok, if we go this way, it could be as simple as provide some callback to >> vhost, then vhost can just forward the ioctl through parent_ops. >> >>>>>> 2) For method 2, is there any easy way for user/admin to distinguish e.g >>>>>> ordinary vfio-mdev for vhost from ordinary vfio-mdev? >>>>> I think device-api could be a choice. >>>> Ok. >>>> >>>> >>>>>> I saw you introduce >>>>>> ops matching helper but it's not friendly to management. >>>>> The ops matching helper is just to check whether a given >>>>> vfio-device is based on a mdev device. >>>>> >>>>>> 3) A drawback of 1) and 2) is that it must follow vfio_device_ops that >>>>>> assumes the parameter comes from userspace, it prevents support kernel >>>>>> virtio drivers. >>>>>> >>>>>> 4) So comes the idea of method 3, since it register a new vhost-mdev driver, >>>>>> we can use device specific ops instead of VFIO ones, then we can have a >>>>>> common API between vDPA parent and vhost-mdev/virtio-mdev drivers. >>>>> As the above draft shows, this requires introducing a new >>>>> VFIO device driver. I think Alex's opinion matters here. >> Just to clarify, a new type of mdev driver but provides dummy >> vfio_device_ops for VFIO to make container DMA ioctl work. > I see. Thanks! IIUC, you mean we can provide a very tiny > VFIO device driver in drivers/vhost/mdev.c, e.g.: > > static int vfio_vhost_mdev_open(void *device_data) > { > if (!try_module_get(THIS_MODULE)) > return -ENODEV; > return 0; > } > > static void vfio_vhost_mdev_release(void *device_data) > { > module_put(THIS_MODULE); > } > > static const struct vfio_device_ops vfio_vhost_mdev_dev_ops = { > .name = "vfio-vhost-mdev", > .open = vfio_vhost_mdev_open, > .release = vfio_vhost_mdev_release, > }; > > static int vhost_mdev_probe(struct device *dev) > { > struct mdev_device *mdev = to_mdev_device(dev); > > ... Check the mdev device_id proposed in ... > ... https://lkml.org/lkml/2019/9/12/151 ... To clarify, this should be done through the id_table fields in vhost_mdev_driver, and it should claim it supports virtio-mdev device only: static struct mdev_class_id id_table[] = {     { MDEV_ID_VIRTIO },     { 0 }, }; static struct mdev_driver vhost_mdev_driver = {     ...     .id_table = id_table, } > > return vfio_add_group_dev(dev, &vfio_vhost_mdev_dev_ops, mdev); And in vfio_vhost_mdev_ops, all its need is to just implement vhost-net ioctl and translate them to virtio-mdev transport (e.g device_ops I proposed or ioctls other whatever other method) API. And it could have a dummy ops implementation for the other device_ops. > } > > static void vhost_mdev_remove(struct device *dev) > { > vfio_del_group_dev(dev); > } > > static struct mdev_driver vhost_mdev_driver = { > .name = "vhost_mdev", > .probe = vhost_mdev_probe, > .remove = vhost_mdev_remove, > }; > > So we can bind above mdev driver to the virtio-mdev compatible > mdev devices when we want to use vhost-mdev. > > After binding above driver to the mdev device, we can setup IOMMU > via VFIO and get VFIO device fd of this mdev device, and pass it > to vhost fd (/dev/vhost-mdev) with a SET_BACKEND ioctl. Then what vhost-mdev char device did is just forwarding ioctl back to this vfio device fd which seems a overkill. It's simpler that just do ioctl on the device ops directly. Thanks > > Thanks, > Tiwei > >> Thanks >> >> >>>> Yes, it is. >>>> >>>> Thanks >>>> >>>> From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [RFC v4 0/3] vhost: introduce mdev based hardware backend Date: Fri, 20 Sep 2019 09:30:58 +0800 Message-ID: <43aaf7dc-f08b-8898-3c55-908ff4d68866@redhat.com> References: <20190917010204.30376-1-tiwei.bie@intel.com> <993841ed-942e-c90b-8016-8e7dc76bf13a@redhat.com> <20190917105801.GA24855@___> <20190918102923-mutt-send-email-mst@kernel.org> <20190919154552.GA27657@___> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20190919154552.GA27657@___> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Tiwei Bie Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, zhihong.wang@intel.com, maxime.coquelin@redhat.com, lingshan.zhu@intel.com List-Id: virtualization@lists.linuxfoundation.org Ck9uIDIwMTkvOS8xOSDkuIvljYgxMTo0NSwgVGl3ZWkgQmllIHdyb3RlOgo+IE9uIFRodSwgU2Vw IDE5LCAyMDE5IGF0IDA5OjA4OjExUE0gKzA4MDAsIEphc29uIFdhbmcgd3JvdGU6Cj4+IE9uIDIw MTkvOS8xOCDkuIvljYgxMDozMiwgTWljaGFlbCBTLiBUc2lya2luIHdyb3RlOgo+Pj4+Pj4gU28g SSBoYXZlIHNvbWUgcXVlc3Rpb25zOgo+Pj4+Pj4KPj4+Pj4+IDEpIENvbXBhcmVkIHRvIG1ldGhv ZCAyLCB3aGF0J3MgdGhlIGFkdmFudGFnZSBvZiBjcmVhdGluZyBhIG5ldyB2aG9zdCBjaGFyCj4+ Pj4+PiBkZXZpY2U/IEkgZ3Vlc3MgaXQncyBmb3Iga2VlcCB0aGUgQVBJIGNvbXBhdGliaWxpdHk/ Cj4+Pj4+IE9uZSBiZW5lZml0IGlzIHRoYXQgd2UgY2FuIGF2b2lkIGRvaW5nIHZob3N0IGlvY3Rs cyBvbgo+Pj4+PiBWRklPIGRldmljZSBmZC4KPj4+PiBZZXMsIGJ1dCBhbnkgYmVuZWZpdCBmcm9t IGRvaW5nIHRoaXM/Cj4+PiBJdCBkb2VzIHNlZW0gYSBiaXQgbW9yZSBtb2R1bGFyLCBidXQgaXQn cyBjZXJ0YWlubHkgbm90IGEgYmlnIGRlYWwuCj4+IE9rLCBpZiB3ZSBnbyB0aGlzIHdheSwgaXQg Y291bGQgYmUgYXMgc2ltcGxlIGFzIHByb3ZpZGUgc29tZSBjYWxsYmFjayB0bwo+PiB2aG9zdCwg dGhlbiB2aG9zdCBjYW4ganVzdCBmb3J3YXJkIHRoZSBpb2N0bCB0aHJvdWdoIHBhcmVudF9vcHMu Cj4+Cj4+Pj4+PiAyKSBGb3IgbWV0aG9kIDIsIGlzIHRoZXJlIGFueSBlYXN5IHdheSBmb3IgdXNl ci9hZG1pbiB0byBkaXN0aW5ndWlzaCBlLmcKPj4+Pj4+IG9yZGluYXJ5IHZmaW8tbWRldiBmb3Ig dmhvc3QgZnJvbSBvcmRpbmFyeSB2ZmlvLW1kZXY/Cj4+Pj4+IEkgdGhpbmsgZGV2aWNlLWFwaSBj b3VsZCBiZSBhIGNob2ljZS4KPj4+PiBPay4KPj4+Pgo+Pj4+Cj4+Pj4+PiBJIHNhdyB5b3UgaW50 cm9kdWNlCj4+Pj4+PiBvcHMgbWF0Y2hpbmcgaGVscGVyIGJ1dCBpdCdzIG5vdCBmcmllbmRseSB0 byBtYW5hZ2VtZW50Lgo+Pj4+PiBUaGUgb3BzIG1hdGNoaW5nIGhlbHBlciBpcyBqdXN0IHRvIGNo ZWNrIHdoZXRoZXIgYSBnaXZlbgo+Pj4+PiB2ZmlvLWRldmljZSBpcyBiYXNlZCBvbiBhIG1kZXYg ZGV2aWNlLgo+Pj4+Pgo+Pj4+Pj4gMykgQSBkcmF3YmFjayBvZiAxKSBhbmQgMikgaXMgdGhhdCBp dCBtdXN0IGZvbGxvdyB2ZmlvX2RldmljZV9vcHMgdGhhdAo+Pj4+Pj4gYXNzdW1lcyB0aGUgcGFy YW1ldGVyIGNvbWVzIGZyb20gdXNlcnNwYWNlLCBpdCBwcmV2ZW50cyBzdXBwb3J0IGtlcm5lbAo+ Pj4+Pj4gdmlydGlvIGRyaXZlcnMuCj4+Pj4+Pgo+Pj4+Pj4gNCkgU28gY29tZXMgdGhlIGlkZWEg b2YgbWV0aG9kIDMsIHNpbmNlIGl0IHJlZ2lzdGVyIGEgbmV3IHZob3N0LW1kZXYgZHJpdmVyLAo+ Pj4+Pj4gd2UgY2FuIHVzZSBkZXZpY2Ugc3BlY2lmaWMgb3BzIGluc3RlYWQgb2YgVkZJTyBvbmVz LCB0aGVuIHdlIGNhbiBoYXZlIGEKPj4+Pj4+IGNvbW1vbiBBUEkgYmV0d2VlbiB2RFBBIHBhcmVu dCBhbmQgdmhvc3QtbWRldi92aXJ0aW8tbWRldiBkcml2ZXJzLgo+Pj4+PiBBcyB0aGUgYWJvdmUg ZHJhZnQgc2hvd3MsIHRoaXMgcmVxdWlyZXMgaW50cm9kdWNpbmcgYSBuZXcKPj4+Pj4gVkZJTyBk ZXZpY2UgZHJpdmVyLiBJIHRoaW5rIEFsZXgncyBvcGluaW9uIG1hdHRlcnMgaGVyZS4KPj4gSnVz dCB0byBjbGFyaWZ5LCBhIG5ldyB0eXBlIG9mIG1kZXYgZHJpdmVyIGJ1dCBwcm92aWRlcyBkdW1t eQo+PiB2ZmlvX2RldmljZV9vcHMgZm9yIFZGSU8gdG8gbWFrZSBjb250YWluZXIgRE1BIGlvY3Rs IHdvcmsuCj4gSSBzZWUuIFRoYW5rcyEgSUlVQywgeW91IG1lYW4gd2UgY2FuIHByb3ZpZGUgYSB2 ZXJ5IHRpbnkKPiBWRklPIGRldmljZSBkcml2ZXIgaW4gZHJpdmVycy92aG9zdC9tZGV2LmMsIGUu Zy46Cj4KPiBzdGF0aWMgaW50IHZmaW9fdmhvc3RfbWRldl9vcGVuKHZvaWQgKmRldmljZV9kYXRh KQo+IHsKPiAJaWYgKCF0cnlfbW9kdWxlX2dldChUSElTX01PRFVMRSkpCj4gCQlyZXR1cm4gLUVO T0RFVjsKPiAJcmV0dXJuIDA7Cj4gfQo+Cj4gc3RhdGljIHZvaWQgdmZpb192aG9zdF9tZGV2X3Jl bGVhc2Uodm9pZCAqZGV2aWNlX2RhdGEpCj4gewo+IAltb2R1bGVfcHV0KFRISVNfTU9EVUxFKTsK PiB9Cj4KPiBzdGF0aWMgY29uc3Qgc3RydWN0IHZmaW9fZGV2aWNlX29wcyB2ZmlvX3Zob3N0X21k ZXZfZGV2X29wcyA9IHsKPiAJLm5hbWUJCT0gInZmaW8tdmhvc3QtbWRldiIsCj4gCS5vcGVuCQk9 IHZmaW9fdmhvc3RfbWRldl9vcGVuLAo+IAkucmVsZWFzZQk9IHZmaW9fdmhvc3RfbWRldl9yZWxl YXNlLAo+IH07Cj4KPiBzdGF0aWMgaW50IHZob3N0X21kZXZfcHJvYmUoc3RydWN0IGRldmljZSAq ZGV2KQo+IHsKPiAJc3RydWN0IG1kZXZfZGV2aWNlICptZGV2ID0gdG9fbWRldl9kZXZpY2UoZGV2 KTsKPgo+IAkuLi4gQ2hlY2sgdGhlIG1kZXYgZGV2aWNlX2lkIHByb3Bvc2VkIGluIC4uLgo+IAku Li4gaHR0cHM6Ly9sa21sLm9yZy9sa21sLzIwMTkvOS8xMi8xNTEgLi4uCgoKVG8gY2xhcmlmeSwg dGhpcyBzaG91bGQgYmUgZG9uZSB0aHJvdWdoIHRoZSBpZF90YWJsZSBmaWVsZHMgaW4gCnZob3N0 X21kZXZfZHJpdmVyLCBhbmQgaXQgc2hvdWxkIGNsYWltIGl0IHN1cHBvcnRzIHZpcnRpby1tZGV2 IGRldmljZSBvbmx5OgoKCnN0YXRpYyBzdHJ1Y3QgbWRldl9jbGFzc19pZCBpZF90YWJsZVtdID0g ewogwqDCoMKgIHsgTURFVl9JRF9WSVJUSU8gfSwKIMKgwqDCoCB7IDAgfSwKfTsKCgpzdGF0aWMg c3RydWN0IG1kZXZfZHJpdmVyIHZob3N0X21kZXZfZHJpdmVyID0gewogwqDCoMKgIC4uLgogwqDC oMKgIC5pZF90YWJsZSA9IGlkX3RhYmxlLAp9CgoKPgo+IAlyZXR1cm4gdmZpb19hZGRfZ3JvdXBf ZGV2KGRldiwgJnZmaW9fdmhvc3RfbWRldl9kZXZfb3BzLCBtZGV2KTsKCgpBbmQgaW4gdmZpb192 aG9zdF9tZGV2X29wcywgYWxsIGl0cyBuZWVkIGlzIHRvIGp1c3QgaW1wbGVtZW50IHZob3N0LW5l dCAKaW9jdGwgYW5kIHRyYW5zbGF0ZSB0aGVtIHRvIHZpcnRpby1tZGV2IHRyYW5zcG9ydCAoZS5n IGRldmljZV9vcHMgSSAKcHJvcG9zZWQgb3IgaW9jdGxzIG90aGVyIHdoYXRldmVyIG90aGVyIG1l dGhvZCkgQVBJLiBBbmQgaXQgY291bGQgaGF2ZSBhIApkdW1teSBvcHMgaW1wbGVtZW50YXRpb24g Zm9yIHRoZSBvdGhlciBkZXZpY2Vfb3BzLgoKCj4gfQo+Cj4gc3RhdGljIHZvaWQgdmhvc3RfbWRl dl9yZW1vdmUoc3RydWN0IGRldmljZSAqZGV2KQo+IHsKPiAJdmZpb19kZWxfZ3JvdXBfZGV2KGRl dik7Cj4gfQo+Cj4gc3RhdGljIHN0cnVjdCBtZGV2X2RyaXZlciB2aG9zdF9tZGV2X2RyaXZlciA9 IHsKPiAJLm5hbWUJPSAidmhvc3RfbWRldiIsCj4gCS5wcm9iZQk9IHZob3N0X21kZXZfcHJvYmUs Cj4gCS5yZW1vdmUJPSB2aG9zdF9tZGV2X3JlbW92ZSwKPiB9Owo+Cj4gU28gd2UgY2FuIGJpbmQg YWJvdmUgbWRldiBkcml2ZXIgdG8gdGhlIHZpcnRpby1tZGV2IGNvbXBhdGlibGUKPiBtZGV2IGRl dmljZXMgd2hlbiB3ZSB3YW50IHRvIHVzZSB2aG9zdC1tZGV2Lgo+Cj4gQWZ0ZXIgYmluZGluZyBh Ym92ZSBkcml2ZXIgdG8gdGhlIG1kZXYgZGV2aWNlLCB3ZSBjYW4gc2V0dXAgSU9NTVUKPiB2aWEg VkZJTyBhbmQgZ2V0IFZGSU8gZGV2aWNlIGZkIG9mIHRoaXMgbWRldiBkZXZpY2UsIGFuZCBwYXNz IGl0Cj4gdG8gdmhvc3QgZmQgKC9kZXYvdmhvc3QtbWRldikgd2l0aCBhIFNFVF9CQUNLRU5EIGlv Y3RsLgoKClRoZW4gd2hhdCB2aG9zdC1tZGV2IGNoYXIgZGV2aWNlIGRpZCBpcyBqdXN0IGZvcndh cmRpbmcgaW9jdGwgYmFjayB0byAKdGhpcyB2ZmlvIGRldmljZSBmZCB3aGljaCBzZWVtcyBhIG92 ZXJraWxsLiBJdCdzIHNpbXBsZXIgdGhhdCBqdXN0IGRvIAppb2N0bCBvbiB0aGUgZGV2aWNlIG9w cyBkaXJlY3RseS4KClRoYW5rcwoKCj4KPiBUaGFua3MsCj4gVGl3ZWkKPgo+PiBUaGFua3MKPj4K Pj4KPj4+PiBZZXMsIGl0IGlzLgo+Pj4+Cj4+Pj4gVGhhbmtzCj4+Pj4KPj4+PgpfX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpWaXJ0dWFsaXphdGlvbiBtYWls aW5nIGxpc3QKVmlydHVhbGl6YXRpb25AbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6 Ly9saXN0cy5saW51eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vdmlydHVhbGl6YXRp b24=