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Tsirkin" , stefanha@redhat.com, Stefano Garzarella , slp@redhat.com, dbassey@redhat.com, Albert Esteve Subject: [PATCH v9 5/7] vhost_user.rst: Add GET_SHMEM_CONFIG message Date: Wed, 15 Oct 2025 10:59:28 +0200 Message-ID: <20251015085930.1517330-6-aesteve@redhat.com> In-Reply-To: <20251015085930.1517330-1-aesteve@redhat.com> References: <20251015085930.1517330-1-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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: 2.1.29 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: 1760518970179158500 Content-Type: text/plain; charset="utf-8" Add GET_SHMEM_CONFIG vhost-user frontend message to the spec documentation. Reviewed-by: Alyssa Ross Reviewed-by: Stefan Hajnoczi Signed-off-by: Albert Esteve --- docs/interop/vhost-user.rst | 39 +++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index dab9f3af42..54d64ae75f 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -371,6 +371,20 @@ MMAP request - 0: Pages are mapped read-only - 1: Pages are mapped read-write =20 +VIRTIO Shared Memory Region configuration +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + ++-------------+---------+------------+----+--------------+ +| num regions | padding | mem size 0 | .. | mem size 255 | ++-------------+---------+------------+----+--------------+ + +:num regions: a 32-bit number of regions + +:padding: 32-bit + +:mem size: contains ``num regions`` 64-bit fields representing the size of= each + VIRTIO Shared Memory Region + C structure ----------- =20 @@ -397,6 +411,7 @@ In QEMU the vhost-user message is implemented with the = following struct: VhostUserShared object; VhostUserTransferDeviceState transfer_state; VhostUserMMap mmap; + VhostUserShMemConfig shmem; }; } QEMU_PACKED VhostUserMsg; =20 @@ -1754,6 +1769,30 @@ Front-end message types Using this function requires prior negotiation of the ``VHOST_USER_PROTOCOL_F_DEVICE_STATE`` feature. =20 +``VHOST_USER_GET_SHMEM_CONFIG`` + :id: 44 + :equivalent ioctl: N/A + :request payload: N/A + :reply payload: ``struct VhostUserShMemConfig`` + + When the ``VHOST_USER_PROTOCOL_F_SHMEM`` protocol feature has been + successfully negotiated, this message can be submitted by the front-end + to gather the VIRTIO Shared Memory Region configuration. The back-end wi= ll + respond with the number of VIRTIO Shared Memory Regions it requires, and + each shared memory region size in an array. The shared memory IDs are + represented by the array index. The information returned shall comply + with the following rules: + + * The shared information will remain valid and unchanged for the entire + lifetime of the connection. + + * The Shared Memory Region size must be a multiple of the page size + supported by mmap(2). + + * The size may be 0 if the region is unused. This can happen when the + device does not support an optional feature but does support a feature + that uses a higher shmid. + Back-end message types ---------------------- =20 --=20 2.49.0