From nobody Sun Sep 28 17:41:24 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1757505423; cv=none; d=zohomail.com; s=zohoarc; b=HOeSYDnouUc33qs23X0OcBql6B3zVo/TvoLqg5htjgmhH/3TQLmcL2oPZd32IgCQDCuwSWXB3zyJK78WeB//pGa8vtMX1iTeBXnWbI0ooMqRRZOdyWfyhsgE/wPvPn4H8t0NaOo5JqdHJOM1A27X47jo/BSAP56dE1B7hxmyqZw= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1757505423; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=56lEYxdS9u2mMEy3cKp25B8ggHhbMd+3/bl921MPr9g=; b=KGZ5U60cDeGntVpKShLFaX2q9DApYmuEOqQFlT6iv1hU0IVd4c/2Q04DVOfvbW+NWAb/lp03dZpZQWA/MOA4VXg3iQOlbK/cU9XUsJ8qXlZF99vZ2Od/pXz2GIzfQdxHfh1yDGjxTfPUJ5GWqlUvlwKfBf6IitCNgSe5Qnxo2kY= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1757505423184250.98503114919743; Wed, 10 Sep 2025 04:57:03 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uwJPs-0000iQ-FN; Wed, 10 Sep 2025 07:55:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uwJPp-0000iC-Pt for qemu-devel@nongnu.org; Wed, 10 Sep 2025 07:55:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uwJPe-0001Sy-17 for qemu-devel@nongnu.org; Wed, 10 Sep 2025 07:55:09 -0400 Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-494-6J_r12ojPsScTzrYGENInQ-1; Wed, 10 Sep 2025 07:54:48 -0400 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C077E1956089; Wed, 10 Sep 2025 11:54:46 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.44.33.15]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6D5C51800447; Wed, 10 Sep 2025 11:54:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1757505292; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=56lEYxdS9u2mMEy3cKp25B8ggHhbMd+3/bl921MPr9g=; b=Ml9+rpZetP2z6ChK5pUUv7Sjbo2wcEyY76Lqqg5pmFe5ZWMkh0SRzDvEWvpftiXJx4xj6A ErEeyN0NDpP8sRc1mj7R+FURMTDjZ/djd1GD12xyuKWN3u+h0vstSM7I6TvrwCzxpn7fR0 2uQWeiOd9c/czJh2L484xax6nhs0qME= X-MC-Unique: 6J_r12ojPsScTzrYGENInQ-1 X-Mimecast-MFC-AGG-ID: 6J_r12ojPsScTzrYGENInQ_1757505286 From: Albert Esteve To: qemu-devel@nongnu.org Cc: stevensd@chromium.org, dbassey@redhat.com, Laurent Vivier , Paolo Bonzini , mst@redhat.com, slp@redhat.com, hi@alyssa.is, stefanha@redhat.com, Fabiano Rosas , Stefano Garzarella , jasowang@redhat.com, david@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Albert Esteve Subject: [PATCH v8 3/7] vhost_user.rst: Add SHMEM_MAP/_UNMAP to spec Date: Wed, 10 Sep 2025 13:54:16 +0200 Message-ID: <20250910115420.1012191-4-aesteve@redhat.com> In-Reply-To: <20250910115420.1012191-1-aesteve@redhat.com> References: <20250910115420.1012191-1-aesteve@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=aesteve@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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_PASS=-0.001, T_SPF_HELO_TEMPERROR=0.01 autolearn=ham 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1757505424925116600 Content-Type: text/plain; charset="utf-8" Add SHMEM_MAP/_UNMAP request to the vhost-user spec documentation. Reviewed-by: Stefan Hajnoczi Signed-off-by: Albert Esteve --- docs/interop/vhost-user.rst | 58 +++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 436a94c0ee..dab9f3af42 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -350,6 +350,27 @@ Device state transfer parameters In the future, additional phases might be added e.g. to allow iterative migration while the device is running. =20 +MMAP request +^^^^^^^^^^^^ + ++-------+---------+-----------+------------+-----+-------+ +| shmid | padding | fd_offset | shm_offset | len | flags | ++-------+---------+-----------+------------+-----+-------+ + +:shmid: a 8-bit shared memory region identifier + +:fd_offset: a 64-bit offset of this area from the start + of the supplied file descriptor + +:shm_offset: a 64-bit offset from the start of the + pointed shared memory region + +:len: a 64-bit size of the memory to map + +:flags: a 64-bit value: + - 0: Pages are mapped read-only + - 1: Pages are mapped read-write + C structure ----------- =20 @@ -375,6 +396,7 @@ In QEMU the vhost-user message is implemented with the = following struct: VhostUserInflight inflight; VhostUserShared object; VhostUserTransferDeviceState transfer_state; + VhostUserMMap mmap; }; } QEMU_PACKED VhostUserMsg; =20 @@ -1057,6 +1079,7 @@ Protocol features #define VHOST_USER_PROTOCOL_F_XEN_MMAP 17 #define VHOST_USER_PROTOCOL_F_SHARED_OBJECT 18 #define VHOST_USER_PROTOCOL_F_DEVICE_STATE 19 + #define VHOST_USER_PROTOCOL_F_SHMEM 20 =20 Front-end message types ----------------------- @@ -1865,6 +1888,41 @@ is sent by the front-end. when the operation is successful, or non-zero otherwise. Note that if the operation fails, no fd is sent to the backend. =20 +``VHOST_USER_BACKEND_SHMEM_MAP`` + :id: 9 + :equivalent ioctl: N/A + :request payload: fd and ``struct VhostUserMMap`` + :reply payload: N/A + + When the ``VHOST_USER_PROTOCOL_F_SHMEM`` protocol feature has been + successfully negotiated, this message can be submitted by the backends to + advertise a new mapping to be made in a given VIRTIO Shared Memory Regio= n. + Upon receiving the message, the front-end will mmap the given fd into the + VIRTIO Shared Memory Region with the requested ``shmid``. + If``VHOST_USER_PROTOCOL_F_REPLY_ACK`` is negotiated, and + back-end set the ``VHOST_USER_NEED_REPLY`` flag, the front-end + must respond with zero when operation is successfully completed, + or non-zero otherwise. + + Mapping over an already existing map is not allowed and requests shall f= ail. + Therefore, the memory range in the request must correspond with a valid, + free region of the VIRTIO Shared Memory Region. Also, note that mappings + consume resources and that the request can fail when there are no resour= ces + available. + +``VHOST_USER_BACKEND_SHMEM_UNMAP`` + :id: 10 + :equivalent ioctl: N/A + :request payload: ``struct VhostUserMMap`` + :reply payload: N/A + + When the ``VHOST_USER_PROTOCOL_F_SHMEM`` protocol feature has been + successfully negotiated, this message can be submitted by the backends so + that the front-end un-mmaps a given range (``shm_offset``, ``len``) in t= he + VIRTIO Shared Memory Region with the requested ``shmid``. Note that the + given range shall correspond to the entirety of a valid mapped region. + A reply is generated indicating whether unmapping succeeded. + .. _reply_ack: =20 VHOST_USER_PROTOCOL_F_REPLY_ACK --=20 2.49.0