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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55D87C433F5 for ; Tue, 12 Oct 2021 05:22:28 +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 14F3660698 for ; Tue, 12 Oct 2021 05:22:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 14F3660698 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:33298 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1maAF9-0003BC-8p for qemu-devel@archiver.kernel.org; Tue, 12 Oct 2021 01:22:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52608) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1maAEC-0001o4-L7 for qemu-devel@nongnu.org; Tue, 12 Oct 2021 01:21:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:36810) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1maAE8-0002UY-W3 for qemu-devel@nongnu.org; Tue, 12 Oct 2021 01:21:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634016084; 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=+POhhaUS8c1MDoSohBwHlpWHrfZPmIrrEI3K8C56x9A=; b=X3ek9K7M7xXZJa+r6Oj5apfEm66DvLlrhQ2e/s70b7HTP8PjGslnoZc+me/eFCmFF+kyql EvAXMJ8YWkRGVkEpq3GHEx+OeByR9dqAHn52B2O1Mtuc0lS9X5/CMkpofJH5O5odCneTHg aFKEFh91PbQ2hOOG1oSQ2RkqjB6CgaI= 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-438-lrwp-bFkPjCSHcppSxp1XQ-1; Tue, 12 Oct 2021 01:21:21 -0400 X-MC-Unique: lrwp-bFkPjCSHcppSxp1XQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CF5D811DCF; Tue, 12 Oct 2021 05:21:19 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-14.ams2.redhat.com [10.36.112.14]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 432DF19C79; Tue, 12 Oct 2021 05:21:12 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id B3A14113865F; Tue, 12 Oct 2021 07:21:10 +0200 (CEST) From: Markus Armbruster To: Eugenio =?utf-8?Q?P=C3=A9rez?= Subject: Re: [RFC PATCH v4 15/20] vhost: Shadow virtqueue buffers forwarding References: <20211001070603.307037-1-eperezma@redhat.com> <20211001070603.307037-16-eperezma@redhat.com> Date: Tue, 12 Oct 2021 07:21:10 +0200 In-Reply-To: <20211001070603.307037-16-eperezma@redhat.com> ("Eugenio =?utf-8?Q?P=C3=A9rez=22's?= message of "Fri, 1 Oct 2021 09:05:58 +0200") Message-ID: <87y26yg6nt.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@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=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.049, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-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: Parav Pandit , Juan Quintela , Jason Wang , "Michael S. Tsirkin" , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Harpreet Singh Anand , Xiao W Wang , Stefan Hajnoczi , Eli Cohen , Eric Blake , Michael Lilja , Stefano Garzarella Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Eugenio P=C3=A9rez writes: > Initial version of shadow virtqueue that actually forward buffers. There > are no iommu support at the moment, and that will be addressed in future > patches of this series. Since all vhost-vdpa devices uses forced IOMMU, > this means that SVQ is not usable at this point of the series on any > device. > > For simplicity it only supports modern devices, that expects vring > in little endian, with split ring and no event idx or indirect > descriptors. Support for them will not be added in this series. > > It reuses the VirtQueue code for the device part. The driver part is > based on Linux's virtio_ring driver, but with stripped functionality > and optimizations so it's easier to review. Later commits add simpler > ones. > > SVQ uses VIRTIO_CONFIG_S_DEVICE_STOPPED to pause the device and > retrieve its status (next available idx the device was going to > consume) race-free. It can later reset the device to replace vring > addresses etc. When SVQ starts qemu can resume consuming the guest's > driver ring from that state, without notice from the latter. > > This status bit VIRTIO_CONFIG_S_DEVICE_STOPPED is currently discussed > in VirtIO, and is implemented in qemu VirtIO-net devices in previous > commits. > > Removal of _S_DEVICE_STOPPED bit (in other words, resuming the device) > can be done in the future if an use case arises. At this moment we can > just rely on reseting the full device. > > Signed-off-by: Eugenio P=C3=A9rez > --- > qapi/net.json | 2 +- > hw/virtio/vhost-shadow-virtqueue.c | 237 ++++++++++++++++++++++++++++- > hw/virtio/vhost-vdpa.c | 109 ++++++++++++- > 3 files changed, 337 insertions(+), 11 deletions(-) > > diff --git a/qapi/net.json b/qapi/net.json > index fe546b0e7c..1f4a55f2c5 100644 > --- a/qapi/net.json > +++ b/qapi/net.json > @@ -86,7 +86,7 @@ > # > # @name: the device name of the VirtIO device > # > -# @enable: true to use the alternate shadow VQ notifications > +# @enable: true to use the alternate shadow VQ buffers fowarding path Uh, why does the flag change meaning half-way through this series? > # > # Returns: Error if failure, or 'no error' for success. > # [...]