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Mon, 13 Oct 2025 08:13:20 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.19]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 657161954102; Mon, 13 Oct 2025 08:13:19 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id A6E7821E6A27; Mon, 13 Oct 2025 10:13:16 +0200 (CEST) Resent-To: raphael@enfabrica.net, fam@euphon.net, raphael.s.norwitz@gmail.com, qemu-block@nongnu.org, qemu-devel@nongnu.org, qemu-stable@nongnu.org, d-tatianin@yandex-team.ru, vsementsov@yandex-team.ru, yc-core@yandex-team.ru Resent-From: Markus Armbruster Resent-Date: Mon, 13 Oct 2025 10:13:16 +0200 Resent-Message-ID: <87ms5v8bj7.fsf@pond.sub.org> From: Markus Armbruster To: Vladimir Sementsov-Ogievskiy Cc: mst@redhat.com, sgarzare@redhat.com, raphael@enfabrica.net, qemu-devel@nongnu.org, raphael.s.norwitz@gmail.com, yc-core@yandex-team.ru, d-tatianin@yandex-team.ru, qemu-stable@nongnu.org, Kevin Wolf , Hanna Reitz , Jason Wang , Paolo Bonzini , Fam Zheng , Eric Blake , qemu-block@nongnu.org (open list:Block layer core) Subject: Re: [PATCH v2 02/23] vhost: drop backend_features field In-Reply-To: <20251011232404.561024-3-vsementsov@yandex-team.ru> (Vladimir Sementsov-Ogievskiy's message of "Sun, 12 Oct 2025 02:23:41 +0300") References: <20251011232404.561024-1-vsementsov@yandex-team.ru> <20251011232404.561024-3-vsementsov@yandex-team.ru> Date: Mon, 13 Oct 2025 06:42:10 +0200 Message-ID: <87plar9zvh.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Vladimir Sementsov-Ogievskiy writes: > This field is mostly unused and sometimes confusing (we even have > a TODO-like comment to drop it). Let's finally do. > > The field is used to held VHOST_USER_F_PROTOCOL_FEATURES for vhost-user > and/or VHOST_NET_F_VIRTIO_NET_HDR for vhost-net (which may be > vhost-user-net). But we can simply recalculate these two flags in place > from hdev->features, and from net-client for VHOST_NET_F_VIRTIO_NET_HDR. > > Note: removing field from x-query-virtio-status result is incompatible > change. We can do it because the command is unstable. > > Cc: qemu-stable@nongnu.org > Signed-off-by: Vladimir Sementsov-Ogievskiy You improved the commit message like I suggested, but lost my Acked-by: Markus Armbruster :) [...] > diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h > index 1ee639dd7e..3e69e47833 100644 > --- a/include/hw/virtio/vhost.h > +++ b/include/hw/virtio/vhost.h > @@ -100,16 +100,9 @@ struct vhost_dev { > * > * @features: available features provided by the backend > * @acked_features: final negotiated features with front-end driver > - * > - * @backend_features: this is used in a couple of places to either > - * store VHOST_USER_F_PROTOCOL_FEATURES to apply to > - * VHOST_USER_SET_FEATURES or VHOST_NET_F_VIRTIO_NET_HDR. Its > - * future use should be discouraged and the variable retired as > - * its easy to confuse with the VirtIO backend_features. > */ I guess this is the TODO-like comment mentioned in the commit message. > VIRTIO_DECLARE_FEATURES(features); > VIRTIO_DECLARE_FEATURES(acked_features); > - VIRTIO_DECLARE_FEATURES(backend_features); > > /** > * @protocol_features: is the vhost-user only feature set by > diff --git a/qapi/virtio.json b/qapi/virtio.json > index 05295ab665..b995a5bb6d 100644 > --- a/qapi/virtio.json > +++ b/qapi/virtio.json > @@ -85,8 +85,6 @@ > # > # @acked-features: vhost_dev acked_features > # > -# @backend-features: vhost_dev backend_features > -# > # @protocol-features: vhost_dev protocol_features > # > # @max-queues: vhost_dev max_queues > @@ -106,7 +104,6 @@ > 'vq-index': 'int', > 'features': 'VirtioDeviceFeatures', > 'acked-features': 'VirtioDeviceFeatures', > - 'backend-features': 'VirtioDeviceFeatures', > 'protocol-features': 'VhostDeviceProtocols', > 'max-queues': 'uint64', > 'backend-cap': 'uint64',