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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 BFA75C2D0BF for ; Thu, 5 Dec 2019 13:06:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A4E824648 for ; Thu, 5 Dec 2019 13:06:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gi5M+sA3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729491AbfLENGl (ORCPT ); Thu, 5 Dec 2019 08:06:41 -0500 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:28111 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729398AbfLENGl (ORCPT ); Thu, 5 Dec 2019 08:06:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575551199; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OfNj9jvlaYufjZtJx3ZWZB82pLVEph3DNSDHIgClWdQ=; b=gi5M+sA3SFDv4jkjS6q6U6fAWzpk1DUUbC8+WfEiGfGayQ/vZdLUdSIjw8fchuc0oC8vqj Qlv2X9p8L8ePiXMEdNjx8D6JTwjdEBVaXyJV/FWi9YA19oG9B2Pyqd0kYpU1ITMzDf7Wc4 etaDGT2V5hRMYkyZ8oRSUYU35fEURkk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-419-eSEPXzgRMxGlVpc75bYOAQ-1; Thu, 05 Dec 2019 08:06:36 -0500 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9D02519057DB; Thu, 5 Dec 2019 13:06:34 +0000 (UTC) Received: from [10.72.12.247] (ovpn-12-247.pek2.redhat.com [10.72.12.247]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1938B10016E8; Thu, 5 Dec 2019 13:06:00 +0000 (UTC) Subject: Re: [RFC PATCH 0/9] Introduce mediate ops in vfio-pci To: Yan Zhao Cc: alex.williamson@redhat.com, kevin.tian@intel.com, kvm@vger.kernel.org, libvir-list@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, zhenyuw@linux.intel.com, qemu-devel@nongnu.org, shaopeng.he@intel.com, zhi.a.wang@intel.com References: <20191205032419.29606-1-yan.y.zhao@intel.com> <8bcf603c-f142-f96d-bb11-834d686f5519@redhat.com> <20191205085111.GD31791@joy-OptiPlex-7040> From: Jason Wang Message-ID: Date: Thu, 5 Dec 2019 21:05:54 +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: <20191205085111.GD31791@joy-OptiPlex-7040> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: eSEPXzgRMxGlVpc75bYOAQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/12/5 =E4=B8=8B=E5=8D=884:51, Yan Zhao wrote: > On Thu, Dec 05, 2019 at 02:33:19PM +0800, Jason Wang wrote: >> Hi: >> >> On 2019/12/5 =E4=B8=8A=E5=8D=8811:24, Yan Zhao wrote: >>> For SRIOV devices, VFs are passthroughed into guest directly without ho= st >>> driver mediation. However, when VMs migrating with passthroughed VFs, >>> dynamic host mediation is required to (1) get device states, (2) get >>> dirty pages. Since device states as well as other critical information >>> required for dirty page tracking for VFs are usually retrieved from PFs= , >>> it is handy to provide an extension in PF driver to centralizingly cont= rol >>> VFs' migration. >>> >>> Therefore, in order to realize (1) passthrough VFs at normal time, (2) >>> dynamically trap VFs' bars for dirty page tracking and >> >> A silly question, what's the reason for doing this, is this a must for d= irty >> page tracking? >> > For performance consideration. VFs' bars should be passthoughed at > normal time and only enter into trap state on need. Right, but how does this matter for the case of dirty page tracking? > >>> (3) centralizing >>> VF critical states retrieving and VF controls into one driver, we propo= se >>> to introduce mediate ops on top of current vfio-pci device driver. >>> >>> >>> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ >>> __________ register mediate ops| ___________ ___________ | >>> | |<-----------------------| VF | | | >>> | vfio-pci | | | mediate | | PF driver | | >>> |__________|----------------------->| driver | |___________| >>> | open(pdev) | ----------- | | >>> | | >>> | |_ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _| >>> \|/ \|/ >>> ----------- ------------ >>> | VF | | PF | >>> ----------- ------------ >>> >>> >>> VF mediate driver could be a standalone driver that does not bind to >>> any devices (as in demo code in patches 5-6) or it could be a built-in >>> extension of PF driver (as in patches 7-9) . >>> >>> Rather than directly bind to VF, VF mediate driver register a mediate >>> ops into vfio-pci in driver init. vfio-pci maintains a list of such >>> mediate ops. >>> (Note that: VF mediate driver can register mediate ops into vfio-pci >>> before vfio-pci binding to any devices. And VF mediate driver can >>> support mediating multiple devices.) >>> >>> When opening a device (e.g. a VF), vfio-pci goes through the mediate op= s >>> list and calls each vfio_pci_mediate_ops->open() with pdev of the openi= ng >>> device as a parameter. >>> VF mediate driver should return success or failure depending on it >>> supports the pdev or not. >>> E.g. VF mediate driver would compare its supported VF devfn with the >>> devfn of the passed-in pdev. >>> Once vfio-pci finds a successful vfio_pci_mediate_ops->open(), it will >>> stop querying other mediate ops and bind the opening device with this >>> mediate ops using the returned mediate handle. >>> >>> Further vfio-pci ops (VFIO_DEVICE_GET_REGION_INFO ioctl, rw, mmap) on t= he >>> VF will be intercepted into VF mediate driver as >>> vfio_pci_mediate_ops->get_region_info(), >>> vfio_pci_mediate_ops->rw, >>> vfio_pci_mediate_ops->mmap, and get customized. >>> For vfio_pci_mediate_ops->rw and vfio_pci_mediate_ops->mmap, they will >>> further return 'pt' to indicate whether vfio-pci should further >>> passthrough data to hw. >>> >>> when vfio-pci closes the VF, it calls its vfio_pci_mediate_ops->release= () >>> with a mediate handle as parameter. >>> >>> The mediate handle returned from vfio_pci_mediate_ops->open() lets VF >>> mediate driver be able to differentiate two opening VFs of the same dev= ice >>> id and vendor id. >>> >>> When VF mediate driver exits, it unregisters its mediate ops from >>> vfio-pci. >>> >>> >>> In this patchset, we enable vfio-pci to provide 3 things: >>> (1) calling mediate ops to allow vendor driver customizing default >>> region info/rw/mmap of a region. >>> (2) provide a migration region to support migration >> >> What's the benefit of introducing a region? It looks to me we don't expe= ct >> the region to be accessed directly from guest. Could we simply extend de= vice >> fd ioctl for doing such things? >> > You may take a look on mdev live migration discussions in > https://lists.gnu.org/archive/html/qemu-devel/2019-11/msg01763.html > > or previous discussion at > https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg04908.html, > which has kernel side implemetation https://patchwork.freedesktop.org/ser= ies/56876/ > > generaly speaking, qemu part of live migration is consistent for > vfio-pci + mediate ops way or mdev way. So in mdev, do you still have a mediate driver? Or you expect the parent=20 to implement the region? > The region is only a channel for > QEMU and kernel to communicate information without introducing IOCTLs. Well, at least you introduce new type of region in uapi. So this does=20 not answer why region is better than ioctl. If the region will only be=20 used by qemu, using ioctl is much more easier and straightforward. > > >>> (3) provide a dynamic trap bar info region to allow vendor driver >>> control trap/untrap of device pci bars >>> >>> This vfio-pci + mediate ops way differs from mdev way in that >>> (1) medv way needs to create a 1:1 mdev device on top of one VF, device >>> specific mdev parent driver is bound to VF directly. >>> (2) vfio-pci + mediate ops way does not create mdev devices and VF >>> mediate driver does not bind to VFs. Instead, vfio-pci binds to VFs. >>> >>> The reason why we don't choose the way of writing mdev parent driver is >>> that >>> (1) VFs are almost all the time directly passthroughed. Directly bindin= g >>> to vfio-pci can make most of the code shared/reused. >> >> Can we split out the common parts from vfio-pci? >> > That's very attractive. but one cannot implement a vfio-pci except > export everything in it as common part :) Well, I think there should be not hard to do that. E..g you can route it=20 back to like: vfio -> vfio_mdev -> parent -> vfio_pci >>> If we write a >>> vendor specific mdev parent driver, most of the code (like passthrough >>> style of rw/mmap) still needs to be copied from vfio-pci driver, which = is >>> actually a duplicated and tedious work. >> >> The mediate ops looks quite similar to what vfio-mdev did. And it looks = to >> me we need to consider live migration for mdev as well. In that case, do= we >> still expect mediate ops through VFIO directly? >> >> >>> (2) For features like dynamically trap/untrap pci bars, if they are in >>> vfio-pci, they can be available to most people without repeated code >>> copying and re-testing. >>> (3) with a 1:1 mdev driver which passthrough VFs most of the time, peop= le >>> have to decide whether to bind VFs to vfio-pci or mdev parent driver be= fore >>> it runs into a real migration need. However, if vfio-pci is bound >>> initially, they have no chance to do live migration when there's a need >>> later. >> >> We can teach management layer to do this. >> > No. not possible as vfio-pci by default has no migration region and > dirty page tracking needs vendor's mediation at least for most > passthrough devices now. I'm not quite sure I get here but in this case, just tech them to use=20 the driver that has migration support? Thanks > > Thanks > Yn > >> Thanks >> >> >>> In this patchset, >>> - patches 1-4 enable vfio-pci to call mediate ops registered by vendor >>> driver to mediate/customize region info/rw/mmap. >>> >>> - patches 5-6 provide a standalone sample driver to register a mediate = ops >>> for Intel Graphics Devices. It does not bind to IGDs directly but d= ecides >>> what devices it supports via its pciidlist. It also demonstrates ho= w to >>> dynamic trap a device's PCI bars. (by adding more pciids in its >>> pciidlist, this sample driver actually is not necessarily limited t= o >>> support IGDs) >>> >>> - patch 7-9 provide a sample on i40e driver that supports Intel(R) >>> Ethernet Controller XL710 Family of devices. It supports VF precopy= live >>> migration on Intel's 710 SRIOV. (but we commented out the real >>> implementation of dirty page tracking and device state retrieving p= art >>> to focus on demonstrating framework part. Will send out them in fut= ure >>> versions) >>> patch 7 registers/unregisters VF mediate ops when PF driver >>> probes/removes. It specifies its supporting VFs via >>> vfio_pci_mediate_ops->open(pdev) >>> >>> patch 8 reports device cap of VFIO_PCI_DEVICE_CAP_MIGRATION and >>> provides a sample implementation of migration region. >>> The QEMU part of vfio migration is based on v8 >>> https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg05542.html= . >>> We do not based on recent v9 because we think there are still opens= in >>> dirty page track part in that series. >>> >>> patch 9 reports device cap of VFIO_PCI_DEVICE_CAP_DYNAMIC_TRAP_BAR = and >>> provides an example on how to trap part of bar0 when migration star= ts >>> and passthrough this part of bar0 again when migration fails. >>> >>> Yan Zhao (9): >>> vfio/pci: introduce mediate ops to intercept vfio-pci ops >>> vfio/pci: test existence before calling region->ops >>> vfio/pci: register a default migration region >>> vfio-pci: register default dynamic-trap-bar-info region >>> samples/vfio-pci/igd_dt: sample driver to mediate a passthrough IGD >>> sample/vfio-pci/igd_dt: dynamically trap/untrap subregion of IGD ba= r0 >>> i40e/vf_migration: register mediate_ops to vfio-pci >>> i40e/vf_migration: mediate migration region >>> i40e/vf_migration: support dynamic trap of bar0 >>> >>> drivers/net/ethernet/intel/Kconfig | 2 +- >>> drivers/net/ethernet/intel/i40e/Makefile | 3 +- >>> drivers/net/ethernet/intel/i40e/i40e.h | 2 + >>> drivers/net/ethernet/intel/i40e/i40e_main.c | 3 + >>> .../ethernet/intel/i40e/i40e_vf_migration.c | 626 ++++++++++++++++= ++ >>> .../ethernet/intel/i40e/i40e_vf_migration.h | 78 +++ >>> drivers/vfio/pci/vfio_pci.c | 189 +++++- >>> drivers/vfio/pci/vfio_pci_private.h | 2 + >>> include/linux/vfio.h | 18 + >>> include/uapi/linux/vfio.h | 160 +++++ >>> samples/Kconfig | 6 + >>> samples/Makefile | 1 + >>> samples/vfio-pci/Makefile | 2 + >>> samples/vfio-pci/igd_dt.c | 367 ++++++++++ >>> 14 files changed, 1455 insertions(+), 4 deletions(-) >>> create mode 100644 drivers/net/ethernet/intel/i40e/i40e_vf_migration= .c >>> create mode 100644 drivers/net/ethernet/intel/i40e/i40e_vf_migration= .h >>> create mode 100644 samples/vfio-pci/Makefile >>> create mode 100644 samples/vfio-pci/igd_dt.c >>> 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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 E49B2C43603 for ; Thu, 5 Dec 2019 13:44:47 +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 99D912464D for ; Thu, 5 Dec 2019 13:44:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eSB3t0XG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 99D912464D 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]:54280 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1icrR0-0004sG-5F for qemu-devel@archiver.kernel.org; Thu, 05 Dec 2019 08:44:46 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:45921) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1icrJq-0006cI-QC for qemu-devel@nongnu.org; Thu, 05 Dec 2019 08:37:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1icrJn-0002p3-SR for qemu-devel@nongnu.org; Thu, 05 Dec 2019 08:37:22 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:20277 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1icrJm-0002k1-Gx for qemu-devel@nongnu.org; Thu, 05 Dec 2019 08:37:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575553027; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OfNj9jvlaYufjZtJx3ZWZB82pLVEph3DNSDHIgClWdQ=; b=eSB3t0XGld0XVOER9Jo0O0GSc8UmO86LHHNmzHQ7duk8b94+Tgf9a5T7DJzHvzlmQMndpy VnPAdmMvH1lE/LAnlMu33DrY660uHaWf00hwieuT4Bp2+vKHaYsRtY8MbO2aep9ZirLDw5 jZPk5lkYOoceEJeHLZ0MZmwSuJyO9vE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-419-eSEPXzgRMxGlVpc75bYOAQ-1; Thu, 05 Dec 2019 08:06:36 -0500 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9D02519057DB; Thu, 5 Dec 2019 13:06:34 +0000 (UTC) Received: from [10.72.12.247] (ovpn-12-247.pek2.redhat.com [10.72.12.247]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1938B10016E8; Thu, 5 Dec 2019 13:06:00 +0000 (UTC) Subject: Re: [RFC PATCH 0/9] Introduce mediate ops in vfio-pci To: Yan Zhao References: <20191205032419.29606-1-yan.y.zhao@intel.com> <8bcf603c-f142-f96d-bb11-834d686f5519@redhat.com> <20191205085111.GD31791@joy-OptiPlex-7040> From: Jason Wang Message-ID: Date: Thu, 5 Dec 2019 21:05:54 +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: <20191205085111.GD31791@joy-OptiPlex-7040> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-MC-Unique: eSEPXzgRMxGlVpc75bYOAQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 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, kvm@vger.kernel.org, libvir-list@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, zhenyuw@linux.intel.com, qemu-devel@nongnu.org, alex.williamson@redhat.com, shaopeng.he@intel.com, zhi.a.wang@intel.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2019/12/5 =E4=B8=8B=E5=8D=884:51, Yan Zhao wrote: > On Thu, Dec 05, 2019 at 02:33:19PM +0800, Jason Wang wrote: >> Hi: >> >> On 2019/12/5 =E4=B8=8A=E5=8D=8811:24, Yan Zhao wrote: >>> For SRIOV devices, VFs are passthroughed into guest directly without ho= st >>> driver mediation. However, when VMs migrating with passthroughed VFs, >>> dynamic host mediation is required to (1) get device states, (2) get >>> dirty pages. Since device states as well as other critical information >>> required for dirty page tracking for VFs are usually retrieved from PFs= , >>> it is handy to provide an extension in PF driver to centralizingly cont= rol >>> VFs' migration. >>> >>> Therefore, in order to realize (1) passthrough VFs at normal time, (2) >>> dynamically trap VFs' bars for dirty page tracking and >> >> A silly question, what's the reason for doing this, is this a must for d= irty >> page tracking? >> > For performance consideration. VFs' bars should be passthoughed at > normal time and only enter into trap state on need. Right, but how does this matter for the case of dirty page tracking? > >>> (3) centralizing >>> VF critical states retrieving and VF controls into one driver, we propo= se >>> to introduce mediate ops on top of current vfio-pci device driver. >>> >>> >>> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ >>> __________ register mediate ops| ___________ ___________ | >>> | |<-----------------------| VF | | | >>> | vfio-pci | | | mediate | | PF driver | | >>> |__________|----------------------->| driver | |___________| >>> | open(pdev) | ----------- | | >>> | | >>> | |_ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _| >>> \|/ \|/ >>> ----------- ------------ >>> | VF | | PF | >>> ----------- ------------ >>> >>> >>> VF mediate driver could be a standalone driver that does not bind to >>> any devices (as in demo code in patches 5-6) or it could be a built-in >>> extension of PF driver (as in patches 7-9) . >>> >>> Rather than directly bind to VF, VF mediate driver register a mediate >>> ops into vfio-pci in driver init. vfio-pci maintains a list of such >>> mediate ops. >>> (Note that: VF mediate driver can register mediate ops into vfio-pci >>> before vfio-pci binding to any devices. And VF mediate driver can >>> support mediating multiple devices.) >>> >>> When opening a device (e.g. a VF), vfio-pci goes through the mediate op= s >>> list and calls each vfio_pci_mediate_ops->open() with pdev of the openi= ng >>> device as a parameter. >>> VF mediate driver should return success or failure depending on it >>> supports the pdev or not. >>> E.g. VF mediate driver would compare its supported VF devfn with the >>> devfn of the passed-in pdev. >>> Once vfio-pci finds a successful vfio_pci_mediate_ops->open(), it will >>> stop querying other mediate ops and bind the opening device with this >>> mediate ops using the returned mediate handle. >>> >>> Further vfio-pci ops (VFIO_DEVICE_GET_REGION_INFO ioctl, rw, mmap) on t= he >>> VF will be intercepted into VF mediate driver as >>> vfio_pci_mediate_ops->get_region_info(), >>> vfio_pci_mediate_ops->rw, >>> vfio_pci_mediate_ops->mmap, and get customized. >>> For vfio_pci_mediate_ops->rw and vfio_pci_mediate_ops->mmap, they will >>> further return 'pt' to indicate whether vfio-pci should further >>> passthrough data to hw. >>> >>> when vfio-pci closes the VF, it calls its vfio_pci_mediate_ops->release= () >>> with a mediate handle as parameter. >>> >>> The mediate handle returned from vfio_pci_mediate_ops->open() lets VF >>> mediate driver be able to differentiate two opening VFs of the same dev= ice >>> id and vendor id. >>> >>> When VF mediate driver exits, it unregisters its mediate ops from >>> vfio-pci. >>> >>> >>> In this patchset, we enable vfio-pci to provide 3 things: >>> (1) calling mediate ops to allow vendor driver customizing default >>> region info/rw/mmap of a region. >>> (2) provide a migration region to support migration >> >> What's the benefit of introducing a region? It looks to me we don't expe= ct >> the region to be accessed directly from guest. Could we simply extend de= vice >> fd ioctl for doing such things? >> > You may take a look on mdev live migration discussions in > https://lists.gnu.org/archive/html/qemu-devel/2019-11/msg01763.html > > or previous discussion at > https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg04908.html, > which has kernel side implemetation https://patchwork.freedesktop.org/ser= ies/56876/ > > generaly speaking, qemu part of live migration is consistent for > vfio-pci + mediate ops way or mdev way. So in mdev, do you still have a mediate driver? Or you expect the parent=20 to implement the region? > The region is only a channel for > QEMU and kernel to communicate information without introducing IOCTLs. Well, at least you introduce new type of region in uapi. So this does=20 not answer why region is better than ioctl. If the region will only be=20 used by qemu, using ioctl is much more easier and straightforward. > > >>> (3) provide a dynamic trap bar info region to allow vendor driver >>> control trap/untrap of device pci bars >>> >>> This vfio-pci + mediate ops way differs from mdev way in that >>> (1) medv way needs to create a 1:1 mdev device on top of one VF, device >>> specific mdev parent driver is bound to VF directly. >>> (2) vfio-pci + mediate ops way does not create mdev devices and VF >>> mediate driver does not bind to VFs. Instead, vfio-pci binds to VFs. >>> >>> The reason why we don't choose the way of writing mdev parent driver is >>> that >>> (1) VFs are almost all the time directly passthroughed. Directly bindin= g >>> to vfio-pci can make most of the code shared/reused. >> >> Can we split out the common parts from vfio-pci? >> > That's very attractive. but one cannot implement a vfio-pci except > export everything in it as common part :) Well, I think there should be not hard to do that. E..g you can route it=20 back to like: vfio -> vfio_mdev -> parent -> vfio_pci >>> If we write a >>> vendor specific mdev parent driver, most of the code (like passthrough >>> style of rw/mmap) still needs to be copied from vfio-pci driver, which = is >>> actually a duplicated and tedious work. >> >> The mediate ops looks quite similar to what vfio-mdev did. And it looks = to >> me we need to consider live migration for mdev as well. In that case, do= we >> still expect mediate ops through VFIO directly? >> >> >>> (2) For features like dynamically trap/untrap pci bars, if they are in >>> vfio-pci, they can be available to most people without repeated code >>> copying and re-testing. >>> (3) with a 1:1 mdev driver which passthrough VFs most of the time, peop= le >>> have to decide whether to bind VFs to vfio-pci or mdev parent driver be= fore >>> it runs into a real migration need. However, if vfio-pci is bound >>> initially, they have no chance to do live migration when there's a need >>> later. >> >> We can teach management layer to do this. >> > No. not possible as vfio-pci by default has no migration region and > dirty page tracking needs vendor's mediation at least for most > passthrough devices now. I'm not quite sure I get here but in this case, just tech them to use=20 the driver that has migration support? Thanks > > Thanks > Yn > >> Thanks >> >> >>> In this patchset, >>> - patches 1-4 enable vfio-pci to call mediate ops registered by vendor >>> driver to mediate/customize region info/rw/mmap. >>> >>> - patches 5-6 provide a standalone sample driver to register a mediate = ops >>> for Intel Graphics Devices. It does not bind to IGDs directly but d= ecides >>> what devices it supports via its pciidlist. It also demonstrates ho= w to >>> dynamic trap a device's PCI bars. (by adding more pciids in its >>> pciidlist, this sample driver actually is not necessarily limited t= o >>> support IGDs) >>> >>> - patch 7-9 provide a sample on i40e driver that supports Intel(R) >>> Ethernet Controller XL710 Family of devices. It supports VF precopy= live >>> migration on Intel's 710 SRIOV. (but we commented out the real >>> implementation of dirty page tracking and device state retrieving p= art >>> to focus on demonstrating framework part. Will send out them in fut= ure >>> versions) >>> patch 7 registers/unregisters VF mediate ops when PF driver >>> probes/removes. It specifies its supporting VFs via >>> vfio_pci_mediate_ops->open(pdev) >>> >>> patch 8 reports device cap of VFIO_PCI_DEVICE_CAP_MIGRATION and >>> provides a sample implementation of migration region. >>> The QEMU part of vfio migration is based on v8 >>> https://lists.gnu.org/archive/html/qemu-devel/2019-08/msg05542.html= . >>> We do not based on recent v9 because we think there are still opens= in >>> dirty page track part in that series. >>> >>> patch 9 reports device cap of VFIO_PCI_DEVICE_CAP_DYNAMIC_TRAP_BAR = and >>> provides an example on how to trap part of bar0 when migration star= ts >>> and passthrough this part of bar0 again when migration fails. >>> >>> Yan Zhao (9): >>> vfio/pci: introduce mediate ops to intercept vfio-pci ops >>> vfio/pci: test existence before calling region->ops >>> vfio/pci: register a default migration region >>> vfio-pci: register default dynamic-trap-bar-info region >>> samples/vfio-pci/igd_dt: sample driver to mediate a passthrough IGD >>> sample/vfio-pci/igd_dt: dynamically trap/untrap subregion of IGD ba= r0 >>> i40e/vf_migration: register mediate_ops to vfio-pci >>> i40e/vf_migration: mediate migration region >>> i40e/vf_migration: support dynamic trap of bar0 >>> >>> drivers/net/ethernet/intel/Kconfig | 2 +- >>> drivers/net/ethernet/intel/i40e/Makefile | 3 +- >>> drivers/net/ethernet/intel/i40e/i40e.h | 2 + >>> drivers/net/ethernet/intel/i40e/i40e_main.c | 3 + >>> .../ethernet/intel/i40e/i40e_vf_migration.c | 626 ++++++++++++++++= ++ >>> .../ethernet/intel/i40e/i40e_vf_migration.h | 78 +++ >>> drivers/vfio/pci/vfio_pci.c | 189 +++++- >>> drivers/vfio/pci/vfio_pci_private.h | 2 + >>> include/linux/vfio.h | 18 + >>> include/uapi/linux/vfio.h | 160 +++++ >>> samples/Kconfig | 6 + >>> samples/Makefile | 1 + >>> samples/vfio-pci/Makefile | 2 + >>> samples/vfio-pci/igd_dt.c | 367 ++++++++++ >>> 14 files changed, 1455 insertions(+), 4 deletions(-) >>> create mode 100644 drivers/net/ethernet/intel/i40e/i40e_vf_migration= .c >>> create mode 100644 drivers/net/ethernet/intel/i40e/i40e_vf_migration= .h >>> create mode 100644 samples/vfio-pci/Makefile >>> create mode 100644 samples/vfio-pci/igd_dt.c >>>