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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by DS3PEPF000099DF.mail.protection.outlook.com (10.167.17.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9587.10 via Frontend Transport; Tue, 3 Feb 2026 19:48:07 +0000 Received: from localhost (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 3 Feb 2026 13:48:06 -0600 Date: Tue, 3 Feb 2026 20:48:00 +0100 From: "Edgar E. Iglesias" To: "Michael S. Tsirkin" CC: Bill Mills , , Bertrand Marquis , Arnaud Pouliquen , Viresh Kumar , Alex Bennee , Armelle Laine Subject: Re: [PATCH v1 0/4] virtio-msg transport layer Message-ID: References: <20260126163230.1122685-1-bill.mills@linaro.org> <20260203081952-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: virtio-comment@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260203081952-mutt-send-email-mst@kernel.org> User-Agent: Mutt/2.2.14+84 (2efcabc4) (2026-01-25) X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF000099DF:EE_|SJ2PR12MB8876:EE_ X-MS-Office365-Filtering-Correlation-Id: c5ef8d20-6e6b-4b67-9054-08de635d2706 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|36860700013|1800799024|13003099007|7142099003; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?KiXQ65qHYpLQSpa/sen+7pxCtKTbLvhvGoQrjmPgt6ZOO0Qdhi9xOGDhVoqI?= =?us-ascii?Q?AlZyN2TwIAk0GnLnbPdkwhEiAkRRcETxfkv2PJgQVE5dbj4PvFs9QvjKrTxc?= =?us-ascii?Q?UaEDcTlkgfA9SKuJALhedHrdFd1HySzdzkDgv+/iErL39WtJd3kMc+x8jPob?= =?us-ascii?Q?yDYKdoFRWZNx55prjnSoFhxcAO8cndK1TJiH0wRM81m5zTC4T/kBiiyDCxfN?= =?us-ascii?Q?nc5t4vaMLh7rlDqVqRr3yrlnyHLLMvDtHhE8Yv9Q7z2BTHjECcqWDpZgBiH+?= =?us-ascii?Q?T15tb72Wp9eZQ9JwWvLB/NRvWW0sTaIBsZk8VfzONc4tO+nqiHux5ycFg25U?= =?us-ascii?Q?MxOMZuigWpMWiNP3bHGsn1xsThNyCKoHbcWPJXajMK7H52x2q4M+xP4eeOjU?= =?us-ascii?Q?ktawmhm8ibQC9GP4oFEHbTIW/xC0GJJ/MwMPlGnQ2E0Ep/IDD9wRKPTA3zCA?= =?us-ascii?Q?suGnJ9+bvRuEM1ZiUrOy46S28a+UCUrfy6bC9rMgya4mHt1+NzcYrTv2AtCt?= =?us-ascii?Q?C/0kXVLj/b1kO/l3aE7ByQUrY4skuh36xeEIzr4byryX0RBOUJF1sRggvF/g?= =?us-ascii?Q?FgZ0hwSEER+kdWgFnT09edNiA5a4Dm0zQnXzl++35Q0pLtO0UqdXEgt4W0QG?= =?us-ascii?Q?efegg9hUsDR+Gutn0h18EotcZwFk4xeHW0wYAmhRIKffz3+fM5kS76MezSwG?= =?us-ascii?Q?EzaZw2D/Ps70bEiU2Om1gevvsWuzUBpJ+LCpWHkJf157r534elsefOtueUoc?= =?us-ascii?Q?qDL/KxluiY7Z/snfExaAYSqN5VT4vBRwcV5fTBJ0O7U2OkXCQeNQ30n1dGNh?= =?us-ascii?Q?GqrJXGpZtBVJsJAYP3o4xCyCHkII3a4W81VwqyMEkwPvIvIcbwQLyhEx709+?= =?us-ascii?Q?bWSZXM9LcEzmHj7rzccLFAZJ8BFn6VbtHj8AW/s2MznaA//Nkbl4tzQcOaQ7?= =?us-ascii?Q?yKQ5eTx5kHRI25dlk/trVhzAfP+GzEcjOzM2+OmL9leh9/XuJASggZFD1syV?= =?us-ascii?Q?IAUp12hQNlBmXaFKFRdiuQG5O/iUBEl/RpacfL6AsXyf867rr3MZRPhvsvsj?= =?us-ascii?Q?0k69v9k77f33kBKPkS5HDR4RU6pDvCDUkahFZyi7RgKSxnfVNsPhDaaVdWHx?= =?us-ascii?Q?pJoyaFhmHW+eUr6MSrWApU+ChtTCbv55LVMwvAjSGizbFy93tXK/B5iJukSB?= =?us-ascii?Q?H+aRL1kh0FtDoAfxYHPO+58bdpXYWcONGVFMo3b/B6bKC6UrRgEWy7la60Db?= =?us-ascii?Q?pmH4Sn2V5pjExIhFbs8TnGprbx5GZzIVLb3xMeuiyFW2nILTDC1Y8xoIFMjr?= =?us-ascii?Q?zQX6bVc8pHp89fjJJRMbesXmQJIdkkBsqkC+hHEE2K+6mRrl0GYubdwPcHR/?= =?us-ascii?Q?wkUlNYqj2a4XqlUW3jnhgwxigDgLfaQWzWBeqxZQnefTLI57llkvhGVh3nxh?= =?us-ascii?Q?xqp8Gey07QpIU2rc7zq4bT7yF0+SweoAQvKqujf4G6RpJaDTPvCSBFSqL2U2?= =?us-ascii?Q?+nZyx1o+3yJwnY2lzMuRlK1dycyxkfy09ifyFJu0DA5MSYqdKAWeI1XvmXnC?= =?us-ascii?Q?tFkRupAVFKozMxYVwPFr8Q/M+w8wXGA301S187O08iWOlvw9tAwy+6W25idz?= =?us-ascii?Q?WvBohyFTOVqKdtmJVRLg6Zk=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(82310400026)(376014)(36860700013)(1800799024)(13003099007)(7142099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 0P2/WGEP/JlbQoNsTwKOuTFhVG1SsR0XHGfgudbvJHf0STMAptKJA5gDQodRu1wqbS4GAgN8Kf3eEawanHxNQQZW1StinI/jNXPCjlYV7a+BiPWxz1DVlOQjSSLsYANnxY/UI2FLRAcBDR8M7GJhYwavD8jGwshPUHYowbaHdrgH6AoN0qymPSg/rmO3BT2e7sZV6trofJRckE/1DlP8mIrDWK/P+vOyJl/m+JUnPdSiaTYzoudvQfb/KH4Zo6cGx1byi44fSHCNCNPKeFK7EwzkmYDnFQNIwcIWmdmf73UfN9Wt1DsqdoI312Jm9jcDdbT2LpXOiuOE+wRW+oww3B6T0+UVy+VVvVQ8pebEbAINCHR09ruiS7I95CB5Qun3OBlIlNyG8I8Y5GzNs6DbaxsjalV0iKwc7QutaFsT/xdhao0T5N+RlTbhmyKRmSAM X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Feb 2026 19:48:07.0300 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c5ef8d20-6e6b-4b67-9054-08de635d2706 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS3PEPF000099DF.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB8876 On Tue, Feb 03, 2026 at 08:21:01AM -0500, Michael S. Tsirkin wrote: > On Mon, Jan 26, 2026 at 11:32:26AM -0500, Bill Mills wrote: > > This series adds the virtio-msg transport layer. > > > > The individuals and organizations involved in this effort have had difficulty in > > using the existing virtio-transports in various situations and desire to add one > > more transport that performs its transport layer operations by sending and > > receiving messages. > > Is it arm and linaro, or more? > If more, could we get some acks on list from the people involved? > > AMD is also involved, I've acked patches 1, 3, and 4 (patch 2 has my Signed-off-by). Cheers, Edgar > > Implementations of virtio-msg will normally be done in multiple layers: > > * common / device level > > * bus level > > > > The common / device level defines the messages exchanged between the driver > > and a device. This common part should lead to a common driver holding most > > of the virtio specifics and can be shared by all virtio-msg bus implementations. > > The kernel implementation in [3] shows this separation. As with other transport > > layers, virtio-msg should not require modifications to existing virtio device > > implementations (virtio-net, virtio-blk etc). The common / device level is the > > main focus of this version of the patch series. > > > > The virtio-msg bus level implements the normal things a bus defines > > (enumeration, dma operations, etc) but also implements the message send and > > receive operations. A number of bus implementations are envisioned, > > some of which will be reusable and general purpose. Other bus implementations > > might be unique to a given situation, for example only used by a PCIe card > > and its driver. > > > > The standard bus messages are an effort to avoid different bus implementations > > doing the same thing in different ways for no good reason. However the > > different environments will require different things. Instead of trying to > > anticipate all needs and provide something very abstract, we think > > implementation specific messages will be needed at the bus level. Over time, > > if we see similar messages across multiple bus implementations, we will move to > > standardize a bus level message for that. > > > > We are working on a few reusable bus implementations: > > > > * virtio-msg-ffa based on Arm FF-A interface for use between: > > * normal world and secure world > > * host and VM or VM to VM > > * Can be used w/ or with out a hypervisor > > * Any Hypervisor that implements FF-A can be used > > * We have this working with pKVM and Xen > > * We have this working with Trusty and OP-TEE > > > > * virtio-msg-amp for use between heterogenous systems > > * The main processors and its co-processors on an AMP SOC > > * Two or more systems connected via PCIe > > * Minimal requirements: bi-directional interrupts and > > at least one shared memory area > > * hvac-demo has 2 demos of this > > * This is working on two hardware platforms > > > > * virtio-msg-loopback for userspace implemented devices > > * Allows user space to provide devices to its own kernel > > * This is similar to fuse, cuse or loopback block devices but for virtio > > * hvac-demo has a demo > > > > We also anticipate a few more: > > > > * virtio-msg-xen specific to Xen > > * Usable on any Xen system (including x86 where FF-A does not exist) > > * Using Xen events and page grants > > > > * virtio-msg over admin virtqueues > > * This allows any virtio-pci device that supports admin virtqueues to also > > support a virtio-msg bus that supports sub devices > > * [We are looking for collaborators for this work] > > > > Changes since RFC2: > > > > Spec Functional: > > * Made the common message header 8 bytes and added a token for optional use > > when parallel outstanding requests are possible > > * Made the 8 byte fields align to 8 byte offsets. > > This effects the {SET,GET}_VQUEUE messages > > * Many conformance cases have been tightened. > > > > Spec Editorial: > > * Major restructure to better align with virtio spec > > * Conformance model now matches other transports > > * Use C structures to define messages instead of tables > > * Added a section to describe how responses are matched to requests > > This includes the use of the new token field > > * Redefined / better described error handling between transport and bus > > layers to eliminate the need for the bus to generate fake response messages > > * Included editorial feedback from RFC2 > > > > Eco-system: > > * Added virtio-msg-loopback demo > > * Arm has published the first draft of the virtio-msg over FFA spec [6] > > * virtio-msg over FFA has been demonstrated with both Trusty and OP-TEE > > secure world > > * LKML RFC has been sent [7] > > * QEMU RFC has been sent [8] > > > > This is the first non-RFC patch series. The known short comings have been > > addressed. We ask for review in earnest on this series and thank you for > > any feedback you can provide. > > > > Background info and work in progress implementations: > > * HVAC project page with intro slides [1] > > * HVAC demo repo w/ instructions in README.md [2] > > * Kernel w/ virtio-msg common level and ffa support [3] > > * QEMU w/ support for one form of virtio-msg-amp [4] > > * Portable RTOS library w/ one form of virtio-msg-amp [5] > > > > In addition to the QEMU system based demos in the hvac-demo repo, we also have > > two hardware systems running: > > * AMD x86 + AMD Arm Versal connected via PCIe > > * ST STM32MP157 A7 Linux using virtio-i2c provided by M4 Zephyr > > > > Please note that although the demos work, a few have not been aligned > > with this version of the spec. > > > > [1] https://linaro.atlassian.net/wiki/spaces/HVAC/overview > > [2] https://github.com/wmamills/hvac-demo > > [3] https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git/log/?h=virtio/msg > > [4] https://github.com/edgarigl/qemu/commits/edgar/virtio-msg-rfc/ > > [5] https://github.com/arnopo/open-amp/commits/virtio-msg/ > > [6] https://documentation-service.arm.com/static/68f647791134f773ab3f0a7c > > [7] https://lore.kernel.org/all/cover.1753865268.git.viresh.kumar@linaro.org/ > > [8] https://mail.gnu.org/archive/html/qemu-devel/2025-10/msg07438.html > > > > Bertrand Marquis (2): > > virtio-msg: add new command for bus normative > > virtio-msg: add conformance entries in conformance chapter > > > > Bill Mills (2): > > virtio-msg: Add virtio-msg, a message based virtio transport layer > > virtio-msg: link virtio-msg content > > > > commands.tex | 3 +- > > conformance.tex | 105 ++- > > content.tex | 1 + > > transport-msg.tex | 1640 +++++++++++++++++++++++++++++++++++++++++++++ > > 4 files changed, 1746 insertions(+), 3 deletions(-) > > create mode 100644 transport-msg.tex > > > > -- > > 2.34.1 > > >