From patchwork Tue Jul 4 12:36:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Alex_Benn=C3=A9e?= X-Patchwork-Id: 1803191 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256 header.s=google header.b=KublXLyF; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4QwMk613rNz20b1 for ; Tue, 4 Jul 2023 22:37:02 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qGfGt-0005Lq-51; Tue, 04 Jul 2023 08:36:43 -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 1qGfGr-0005CN-5v for qemu-devel@nongnu.org; Tue, 04 Jul 2023 08:36:41 -0400 Received: from mail-wr1-x436.google.com ([2a00:1450:4864:20::436]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qGfGp-0002wk-6B for qemu-devel@nongnu.org; Tue, 04 Jul 2023 08:36:40 -0400 Received: by mail-wr1-x436.google.com with SMTP id ffacd0b85a97d-3143798f542so2208605f8f.2 for ; Tue, 04 Jul 2023 05:36:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1688474197; x=1691066197; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=sdqM9qea1gluYMtuxISIShwJNmf3aOXgi8u2chJ8Mqc=; b=KublXLyFGdbsLhFpEUVt++PgUs9aKclaLrLvP6kqGFMTZOsEOvA19VHjpuRJeP5jEW PlHe/11iujAx66XyBU5htmeEl1zB/osGzSebNpOKOUvqQsRwbEYDY+BFf8YPZTBgUL70 A+4UecndPUgakRghoD1o714sKh3DP2WNDNWWhlIv2kkAOu0ISisjpMXNP5iT2It6uC09 QmI7JQIgwrtpGKdfMpcd5cNWBRWtNpQhQL+AeeHbZgBQzhWesPBzkwyDLb3qdaMCvMCI DuHJDfb56ZlxMOwsQ5EiAUtHL4WjLvvRBaFDzyuPCYxcfnwlJWoZaReVs+Nh5mzMbNkM aaaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688474197; x=1691066197; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=sdqM9qea1gluYMtuxISIShwJNmf3aOXgi8u2chJ8Mqc=; b=NWFPc42ySwz40MrFv2wJ+Xdmms6Sx3XM0No+6F4S1hLzQoWp5UyllxC/tfSI4E8lOG wKHm4epUkP3FZaRUw5ZWCAYFPGnGWXdDtoqxmCDkkIJBEHpmTn+66R5Ew3gRxcZoXEUx HQjqIxhn8g2696Fdc7zGtStpQny4KKVTnJWV6gZjdoZlEMMjI0p208ax1BWpKCvsktIm z3dB69xUeaz5uulTkJSSHd4gbggOVbrhsaiH3cMVmT4s36JTvI2HkhW30RA78kqCXXoe xePnukj85/ArxGhqCtfe3KGOnAh29W3dD+/iObsSOaX0ZNbuPv8wHRl58op7AOsj3HoH Intw== X-Gm-Message-State: ABy/qLb4+7O+xdzh8e6itGihp99nV5f1OnLXxJDuqLJyWqA6uomCPB9z oYmxJldx4vUY5+Gl9v8A6TUAEA== X-Google-Smtp-Source: APBJJlF5bvL3gi1v3zWPv3B1bXUa9h+fhIfUgkdWSqdKmBeq2DBxu2CN6lTXrui4wd13YhXvQxqojQ== X-Received: by 2002:a5d:670a:0:b0:313:eadf:b82d with SMTP id o10-20020a5d670a000000b00313eadfb82dmr9395725wru.69.1688474197450; Tue, 04 Jul 2023 05:36:37 -0700 (PDT) Received: from zen.linaroharston ([85.9.250.243]) by smtp.gmail.com with ESMTPSA id k9-20020adff5c9000000b0031411b7087dsm15334074wrp.20.2023.07.04.05.36.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Jul 2023 05:36:37 -0700 (PDT) Received: from zen.lan (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 8FF211FFBB; Tue, 4 Jul 2023 13:36:36 +0100 (BST) From: =?utf-8?q?Alex_Benn=C3=A9e?= To: qemu-devel@nongnu.org Cc: virtio-dev@lists.oasis-open.org, slp@redhat.com, mst@redhat.com, marcandre.lureau@redhat.com, stefanha@redhat.com, viresh.kumar@linaro.org, sgarzare@redhat.com, takahiro.akashi@linaro.org, erik.schilling@linaro.org, manos.pitsidianakis@linaro.org, mathieu.poirier@linaro.org, =?utf-8?q?Alex_?= =?utf-8?q?Benn=C3=A9e?= Subject: [RFC PATCH] docs/interop: define STANDALONE protocol feature for vhost-user Date: Tue, 4 Jul 2023 13:36:00 +0100 Message-Id: <20230704123600.1808604-1-alex.bennee@linaro.org> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::436; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x436.google.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Currently QEMU has to know some details about the back-end to be able to setup the guest. While various parts of the setup can be delegated to the backend (for example config handling) this is a very piecemeal approach. This patch suggests a new feature flag (VHOST_USER_PROTOCOL_F_STANDALONE) which the back-end can advertise which allows a probe message to be sent to get all the details QEMU needs to know in one message. Signed-off-by: Alex Bennée --- Initial RFC for discussion. I intend to prototype this work with QEMU and one of the rust-vmm vhost-user daemons. --- docs/interop/vhost-user.rst | 37 +++++++++++++++++++++++++++++++++++++ hw/virtio/vhost-user.c | 8 ++++++++ 2 files changed, 45 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 5a070adbc1..85b1b1583a 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -275,6 +275,21 @@ Inflight description :queue size: a 16-bit size of virtqueues +Backend specifications +^^^^^^^^^^^^^^^^^^^^^^ + ++-----------+-------------+------------+------------+ +| device id | config size | min_vqs | max_vqs | ++-----------+-------------+------------+------------+ + +:device id: a 32-bit value holding the VirtIO device ID + +:config size: a 32-bit value holding the config size (see ``VHOST_USER_GET_CONFIG``) + +:min_vqs: a 32-bit value holding the minimum number of vqs supported + +:max_vqs: a 32-bit value holding the maximum number of vqs supported, must be >= min_vqs + C structure ----------- @@ -296,6 +311,7 @@ In QEMU the vhost-user message is implemented with the following struct: VhostUserConfig config; VhostUserVringArea area; VhostUserInflight inflight; + VhostUserBackendSpecs specs; }; } QEMU_PACKED VhostUserMsg; @@ -316,6 +332,7 @@ replies. Here is a list of the ones that do: * ``VHOST_USER_GET_VRING_BASE`` * ``VHOST_USER_SET_LOG_BASE`` (if ``VHOST_USER_PROTOCOL_F_LOG_SHMFD``) * ``VHOST_USER_GET_INFLIGHT_FD`` (if ``VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD``) +* ``VHOST_USER_GET_BACKEND_SPECS`` (if ``VHOST_USER_PROTOCOL_F_STANDALONE``) .. seealso:: @@ -885,6 +902,13 @@ Protocol features #define VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS 15 #define VHOST_USER_PROTOCOL_F_STATUS 16 #define VHOST_USER_PROTOCOL_F_XEN_MMAP 17 + #define VHOST_USER_PROTOCOL_F_STANDALONE 18 + +Some features are only valid in the presence of other supporting +features. In the case of ``VHOST_USER_PROTOCOL_F_STANDALONE`` the +backend must also support ``VHOST_USER_PROTOCOL_F_CONFIG`` and +``VHOST_USER_PROTOCOL_F_STATUS``. + Front-end message types ----------------------- @@ -1440,6 +1464,19 @@ Front-end message types query the back-end for its device status as defined in the Virtio specification. +``VHOST_USER_GET_BACKEND_SPECS`` + :id: 41 + :request payload: N/A + :reply payload: ``Backend specifications`` + + When the ``VHOST_USER_PROTOCOL_F_STANDALONE`` protocol feature has been + successfully negotiated, this message is submitted by the front-end to + query the back-end for its capabilities. This is intended to remove + the need for the front-end to know ahead of time what the VirtIO + device the backend emulates is. + + The reply contains the device id, size of the config space and the + range of VirtQueues the backend supports. Back-end message types ---------------------- diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index c4e0cbd702..28b021d5d3 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -202,6 +202,13 @@ typedef struct VhostUserInflight { uint16_t queue_size; } VhostUserInflight; +typedef struct VhostUserBackendSpecs { + uint32_t device_id; + uint32_t config_size; + uint32_t min_vqs; + uint32_t max_vqs; +} VhostUserBackendSpecs; + typedef struct { VhostUserRequest request; @@ -226,6 +233,7 @@ typedef union { VhostUserCryptoSession session; VhostUserVringArea area; VhostUserInflight inflight; + VhostUserBackendSpecs specs; } VhostUserPayload; typedef struct VhostUserMsg {