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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 52237C5519F for ; Wed, 25 Nov 2020 12:04:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3D18206E5 for ; Wed, 25 Nov 2020 12:04:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TMPVhjwM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728864AbgKYMD7 (ORCPT ); Wed, 25 Nov 2020 07:03:59 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:50943 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727626AbgKYMD7 (ORCPT ); Wed, 25 Nov 2020 07:03:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606305836; 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=sBi4zzPTjwPa6ezOJc3qVXmspXQKwftdXTLsylIrXVc=; b=TMPVhjwMcZXcwPyFT5xt9Tja6DHnaAUlzQRlt5vBJnOngh+7JIGfmIH6+/VC49o1uy1ciP 3Tj+VY6Iuhtdw6HZU6Kl9QRQyLXXw0lkiwM3ZcHuQuC5hRiJ9iYOtN9uApr5HzIo4L3oAj j4/7jKoI5lukX52Je7jy3r6cet7UVHY= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-205-4wElO6V8NWm5L9W1DY0ruA-1; Wed, 25 Nov 2020 07:03:53 -0500 X-MC-Unique: 4wElO6V8NWm5L9W1DY0ruA-1 Received: by mail-qk1-f198.google.com with SMTP id p129so2211639qkc.20 for ; Wed, 25 Nov 2020 04:03:53 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=sBi4zzPTjwPa6ezOJc3qVXmspXQKwftdXTLsylIrXVc=; b=ubxBlZMeEtvVFLFQ4Q1Tjl+JUFg2UuNE4rjra4QOAJvoW37uHgqClaeLBtCrss3Agf BFGad8zuto0SbhMxTBolPET0kdVB+GisnEtt0qW5D3s8Ri1GG5XnFlgvBXCqRldlXZvv sWGbXAFwgibi9hRUgeZ2ih3/PwhhxQ8Omb1/ejF8RMkKT6Ldbu/fj7N7+A1m8uP+7oeg tL4fyaCbnh/wlLIn+xMxPT8XZ9l2Soi73fKX5NtcdYG/z3j9CTc7Al4ea2ap2efi/HZp liVAMsED/YQCb9cuv6sXkBq4lTf6VbCsi7yx0morqXzm+vyOJLF+Tz7YsIK6IVorF8Q8 Yxig== X-Gm-Message-State: AOAM530xErAPmHaNwkNIFTGNYhCRjmkleBkc+/eMVamgdDMtOBbaHp5n dMJsng3KqG+Lg/2h8Gbqu3n6HWunPOiGGC1qke3Kd+/2vKt11EDwuQkZ8Nv7M3VC0d8ZUEY9pXN UPDguogINnaOObv/fP8utxESs2/QP X-Received: by 2002:aed:33c4:: with SMTP id v62mr2617115qtd.19.1606305832973; Wed, 25 Nov 2020 04:03:52 -0800 (PST) X-Google-Smtp-Source: ABdhPJxKP8TG3FLn1iuX+VkpqM+uw/CDSl4Sw66nN8a8exNAAObTTprlTJlIEkyK3jUPhy74hYtYQpwHUSYsGX/RRRE= X-Received: by 2002:aed:33c4:: with SMTP id v62mr2617074qtd.19.1606305832640; Wed, 25 Nov 2020 04:03:52 -0800 (PST) MIME-Version: 1.0 References: <20201120185105.279030-1-eperezma@redhat.com> <5a4d0b7a-fb62-9e78-9e85-9262dca57f1c@redhat.com> In-Reply-To: <5a4d0b7a-fb62-9e78-9e85-9262dca57f1c@redhat.com> From: Eugenio Perez Martin Date: Wed, 25 Nov 2020 13:03:16 +0100 Message-ID: Subject: Re: [RFC PATCH 00/27] vDPA software assisted live migration To: Jason Wang Cc: qemu-level , Lars Ganrot , virtualization@lists.linux-foundation.org, Salil Mehta , "Michael S. Tsirkin" , Liran Alon , Rob Miller , Max Gurtovoy , Alex Barba , Stefan Hajnoczi , Jim Harford , Harpreet Singh Anand , Christophe Fontaine , vm , Daniel Daly , Michael Lilja , Stefano Garzarella , Nitin Shrivastav , Lee Ballard , Dmytro Kazantsev , Juan Quintela , kvm list , Howard Cai , Xiao W Wang , Sean Mooney , Parav Pandit , Eli Cohen , Siwei Liu , Stephen Finucane Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Nov 25, 2020 at 8:09 AM Jason Wang wrote: > > > On 2020/11/21 =E4=B8=8A=E5=8D=882:50, Eugenio P=C3=A9rez wrote: > > This series enable vDPA software assisted live migration for vhost-net > > devices. This is a new method of vhost devices migration: Instead of > > relay on vDPA device's dirty logging capability, SW assisted LM > > intercepts dataplane, forwarding the descriptors between VM and device. > > > > In this migration mode, qemu offers a new vring to the device to > > read and write into, and disable vhost notifiers, processing guest and > > vhost notifications in qemu. On used buffer relay, qemu will mark the > > dirty memory as with plain virtio-net devices. This way, devices does > > not need to have dirty page logging capability. > > > > This series is a POC doing SW LM for vhost-net devices, which already > > have dirty page logging capabilities. None of the changes have actual > > effect with current devices until last two patches (26 and 27) are > > applied, but they can be rebased on top of any other. These checks the > > device to meet all requirements, and disable vhost-net devices logging > > so migration goes through SW LM. This last patch is not meant to be > > applied in the final revision, it is in the series just for testing > > purposes. > > > > For use SW assisted LM these vhost-net devices need to be instantiated: > > * With IOMMU (iommu_platform=3Don,ats=3Don) > > * Without event_idx (event_idx=3Doff) > > > So a question is at what level do we want to implement qemu assisted > live migration. To me it could be done at two levels: > > 1) generic vhost level which makes it work for both vhost-net/vhost-user > and vhost-vDPA > 2) a specific type of vhost > > To me, having a generic one looks better but it would be much more > complicated. So what I read from this series is it was a vhost kernel > specific software assisted live migration which is a good start. > Actually it may even have real use case, e.g it can save dirty bitmaps > for guest with large memory. But we need to address the above > limitations first. > > So I would like to know what's the reason for mandating iommu platform > and ats? And I think we need to fix case of event idx support. > There is no specific reason for mandating iommu & ats, it was just started that way. I will extend the patch to support those cases too. > > > > > Just the notification forwarding (with no descriptor relay) can be > > achieved with patches 7 and 9, and starting migration. Partial applies > > between 13 and 24 will not work while migrating on source, and patch > > 25 is needed for the destination to resume network activity. > > > > It is based on the ideas of DPDK SW assisted LM, in the series of > > > Actually we're better than that since there's no need the trick like > hardcoded IOVA for mediated(shadow) virtqueue. > > > > DPDK's https://patchwork.dpdk.org/cover/48370/ . > > > I notice that you do GPA->VA translations and try to establish a VA->VA > (use VA as IOVA) mapping via device IOTLB. This shortcut should work for > vhost-kernel/user but not vhost-vDPA. The reason is that there's no > guarantee that the whole 64bit address range could be used as IOVA. One > example is that for hardware IOMMU like intel, it usually has 47 or 52 > bits of address width. > > So we probably need an IOVA allocator that can make sure the IOVA is not > overlapped and fit for [1]. We can probably build the IOVA for guest VA > via memory listeners. Then we have > > 1) IOVA for GPA > 2) IOVA for shadow VQ > > And advertise IOVA to VA mapping to vhost. > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit= /?id=3D1b48dc03e575a872404f33b04cd237953c5d7498 > Got it, will control it too. Maybe for vhost-net we could directly send iotlb miss for [0,~0ULL]. > > > > > Comments are welcome. > > > > Thanks! > > > > Eugenio P=C3=A9rez (27): > > vhost: Add vhost_dev_can_log > > vhost: Add device callback in vhost_migration_log > > vhost: Move log resize/put to vhost_dev_set_log > > vhost: add vhost_kernel_set_vring_enable > > vhost: Add hdev->dev.sw_lm_vq_handler > > virtio: Add virtio_queue_get_used_notify_split > > vhost: Route guest->host notification through qemu > > vhost: Add a flag for software assisted Live Migration > > vhost: Route host->guest notification through qemu > > vhost: Allocate shadow vring > > virtio: const-ify all virtio_tswap* functions > > virtio: Add virtio_queue_full > > vhost: Send buffers to device > > virtio: Remove virtio_queue_get_used_notify_split > > vhost: Do not invalidate signalled used > > virtio: Expose virtqueue_alloc_element > > vhost: add vhost_vring_set_notification_rcu > > vhost: add vhost_vring_poll_rcu > > vhost: add vhost_vring_get_buf_rcu > > vhost: Return used buffers > > vhost: Add vhost_virtqueue_memory_unmap > > vhost: Add vhost_virtqueue_memory_map > > vhost: unmap qemu's shadow virtqueues on sw live migration > > vhost: iommu changes > > vhost: Do not commit vhost used idx on vhost_virtqueue_stop > > vhost: Add vhost_hdev_can_sw_lm > > vhost: forbid vhost devices logging > > > > hw/virtio/vhost-sw-lm-ring.h | 39 +++ > > include/hw/virtio/vhost.h | 5 + > > include/hw/virtio/virtio-access.h | 8 +- > > include/hw/virtio/virtio.h | 4 + > > hw/net/virtio-net.c | 39 ++- > > hw/virtio/vhost-backend.c | 29 ++ > > hw/virtio/vhost-sw-lm-ring.c | 268 +++++++++++++++++++ > > hw/virtio/vhost.c | 431 +++++++++++++++++++++++++----= - > > hw/virtio/virtio.c | 18 +- > > hw/virtio/meson.build | 2 +- > > 10 files changed, 758 insertions(+), 85 deletions(-) > > create mode 100644 hw/virtio/vhost-sw-lm-ring.h > > create mode 100644 hw/virtio/vhost-sw-lm-ring.c > > > So this looks like a pretty huge patchset which I'm trying to think of > ways to split. An idea is to do this is two steps > > 1) implement a shadow virtqueue mode for vhost first (w/o live > migration). Then we can test descriptors relay, IOVA allocating, etc. How would that mode be activated if it is not tied to live migration? New backend/command line switch? Maybe it is better to also start with no iommu & ats support and add it on = top. > 2) add live migration support on top > > And it looks to me it's better to split the shadow virtqueue (virtio > driver part) into an independent file. And use generic name (w/o > "shadow") in order to be reused by other use cases as well. > I think the same. Thanks! > Thoughts? > 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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 19D22C5519F for ; Wed, 25 Nov 2020 12:05:24 +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 81064206E5 for ; Wed, 25 Nov 2020 12:05:23 +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="TMPVhjwM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81064206E5 Authentication-Results: mail.kernel.org; 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Wed, 25 Nov 2020 04:03:52 -0800 (PST) X-Google-Smtp-Source: ABdhPJxKP8TG3FLn1iuX+VkpqM+uw/CDSl4Sw66nN8a8exNAAObTTprlTJlIEkyK3jUPhy74hYtYQpwHUSYsGX/RRRE= X-Received: by 2002:aed:33c4:: with SMTP id v62mr2617074qtd.19.1606305832640; Wed, 25 Nov 2020 04:03:52 -0800 (PST) MIME-Version: 1.0 References: <20201120185105.279030-1-eperezma@redhat.com> <5a4d0b7a-fb62-9e78-9e85-9262dca57f1c@redhat.com> In-Reply-To: <5a4d0b7a-fb62-9e78-9e85-9262dca57f1c@redhat.com> From: Eugenio Perez Martin Date: Wed, 25 Nov 2020 13:03:16 +0100 Message-ID: Subject: Re: [RFC PATCH 00/27] vDPA software assisted live migration To: Jason Wang Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eperezma@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=63.128.21.124; envelope-from=eperezma@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: kvm list , "Michael S. Tsirkin" , qemu-level , Daniel Daly , virtualization@lists.linux-foundation.org, Liran Alon , Eli Cohen , Nitin Shrivastav , Alex Barba , Christophe Fontaine , Juan Quintela , Lee Ballard , Lars Ganrot , Rob Miller , Stefano Garzarella , Howard Cai , Parav Pandit , vm , Salil Mehta , Stephen Finucane , Xiao W Wang , Sean Mooney , Stefan Hajnoczi , Jim Harford , Dmytro Kazantsev , Siwei Liu , Harpreet Singh Anand , Michael Lilja , Max Gurtovoy Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Nov 25, 2020 at 8:09 AM Jason Wang wrote: > > > On 2020/11/21 =E4=B8=8A=E5=8D=882:50, Eugenio P=C3=A9rez wrote: > > This series enable vDPA software assisted live migration for vhost-net > > devices. This is a new method of vhost devices migration: Instead of > > relay on vDPA device's dirty logging capability, SW assisted LM > > intercepts dataplane, forwarding the descriptors between VM and device. > > > > In this migration mode, qemu offers a new vring to the device to > > read and write into, and disable vhost notifiers, processing guest and > > vhost notifications in qemu. On used buffer relay, qemu will mark the > > dirty memory as with plain virtio-net devices. This way, devices does > > not need to have dirty page logging capability. > > > > This series is a POC doing SW LM for vhost-net devices, which already > > have dirty page logging capabilities. None of the changes have actual > > effect with current devices until last two patches (26 and 27) are > > applied, but they can be rebased on top of any other. These checks the > > device to meet all requirements, and disable vhost-net devices logging > > so migration goes through SW LM. This last patch is not meant to be > > applied in the final revision, it is in the series just for testing > > purposes. > > > > For use SW assisted LM these vhost-net devices need to be instantiated: > > * With IOMMU (iommu_platform=3Don,ats=3Don) > > * Without event_idx (event_idx=3Doff) > > > So a question is at what level do we want to implement qemu assisted > live migration. To me it could be done at two levels: > > 1) generic vhost level which makes it work for both vhost-net/vhost-user > and vhost-vDPA > 2) a specific type of vhost > > To me, having a generic one looks better but it would be much more > complicated. So what I read from this series is it was a vhost kernel > specific software assisted live migration which is a good start. > Actually it may even have real use case, e.g it can save dirty bitmaps > for guest with large memory. But we need to address the above > limitations first. > > So I would like to know what's the reason for mandating iommu platform > and ats? And I think we need to fix case of event idx support. > There is no specific reason for mandating iommu & ats, it was just started that way. I will extend the patch to support those cases too. > > > > > Just the notification forwarding (with no descriptor relay) can be > > achieved with patches 7 and 9, and starting migration. Partial applies > > between 13 and 24 will not work while migrating on source, and patch > > 25 is needed for the destination to resume network activity. > > > > It is based on the ideas of DPDK SW assisted LM, in the series of > > > Actually we're better than that since there's no need the trick like > hardcoded IOVA for mediated(shadow) virtqueue. > > > > DPDK's https://patchwork.dpdk.org/cover/48370/ . > > > I notice that you do GPA->VA translations and try to establish a VA->VA > (use VA as IOVA) mapping via device IOTLB. This shortcut should work for > vhost-kernel/user but not vhost-vDPA. The reason is that there's no > guarantee that the whole 64bit address range could be used as IOVA. One > example is that for hardware IOMMU like intel, it usually has 47 or 52 > bits of address width. > > So we probably need an IOVA allocator that can make sure the IOVA is not > overlapped and fit for [1]. We can probably build the IOVA for guest VA > via memory listeners. Then we have > > 1) IOVA for GPA > 2) IOVA for shadow VQ > > And advertise IOVA to VA mapping to vhost. > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit= /?id=3D1b48dc03e575a872404f33b04cd237953c5d7498 > Got it, will control it too. Maybe for vhost-net we could directly send iotlb miss for [0,~0ULL]. > > > > > Comments are welcome. > > > > Thanks! > > > > Eugenio P=C3=A9rez (27): > > vhost: Add vhost_dev_can_log > > vhost: Add device callback in vhost_migration_log > > vhost: Move log resize/put to vhost_dev_set_log > > vhost: add vhost_kernel_set_vring_enable > > vhost: Add hdev->dev.sw_lm_vq_handler > > virtio: Add virtio_queue_get_used_notify_split > > vhost: Route guest->host notification through qemu > > vhost: Add a flag for software assisted Live Migration > > vhost: Route host->guest notification through qemu > > vhost: Allocate shadow vring > > virtio: const-ify all virtio_tswap* functions > > virtio: Add virtio_queue_full > > vhost: Send buffers to device > > virtio: Remove virtio_queue_get_used_notify_split > > vhost: Do not invalidate signalled used > > virtio: Expose virtqueue_alloc_element > > vhost: add vhost_vring_set_notification_rcu > > vhost: add vhost_vring_poll_rcu > > vhost: add vhost_vring_get_buf_rcu > > vhost: Return used buffers > > vhost: Add vhost_virtqueue_memory_unmap > > vhost: Add vhost_virtqueue_memory_map > > vhost: unmap qemu's shadow virtqueues on sw live migration > > vhost: iommu changes > > vhost: Do not commit vhost used idx on vhost_virtqueue_stop > > vhost: Add vhost_hdev_can_sw_lm > > vhost: forbid vhost devices logging > > > > hw/virtio/vhost-sw-lm-ring.h | 39 +++ > > include/hw/virtio/vhost.h | 5 + > > include/hw/virtio/virtio-access.h | 8 +- > > include/hw/virtio/virtio.h | 4 + > > hw/net/virtio-net.c | 39 ++- > > hw/virtio/vhost-backend.c | 29 ++ > > hw/virtio/vhost-sw-lm-ring.c | 268 +++++++++++++++++++ > > hw/virtio/vhost.c | 431 +++++++++++++++++++++++++----= - > > hw/virtio/virtio.c | 18 +- > > hw/virtio/meson.build | 2 +- > > 10 files changed, 758 insertions(+), 85 deletions(-) > > create mode 100644 hw/virtio/vhost-sw-lm-ring.h > > create mode 100644 hw/virtio/vhost-sw-lm-ring.c > > > So this looks like a pretty huge patchset which I'm trying to think of > ways to split. An idea is to do this is two steps > > 1) implement a shadow virtqueue mode for vhost first (w/o live > migration). Then we can test descriptors relay, IOVA allocating, etc. How would that mode be activated if it is not tied to live migration? New backend/command line switch? Maybe it is better to also start with no iommu & ats support and add it on = top. > 2) add live migration support on top > > And it looks to me it's better to split the shadow virtqueue (virtio > driver part) into an independent file. And use generic name (w/o > "shadow") in order to be reused by other use cases as well. > I think the same. Thanks! > Thoughts? >