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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739810508; 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=Uw+kJrcc03MeOrITLQiE+ix6zWcHlf6Spg7JUuKfvQo=; b=c/3qmZQCoAnSP9OQ5ZWQHvq/nS2IrFMq1So4/yEGTvJQ2vtuJibfNC00191Iz0u7z/Xtol mdJQGGh6vyN2Mdr7icvqLoiWrREZRme2O9u3VKLusMujiakU3PkruNTfCPto+DFSK/jz6y Vli3CELgj7ce8YvCYw3ptnkdpUbK6Ho= X-MC-Unique: lMYQWpJ4O4OyNhBZn4ZmJQ-1 X-Mimecast-MFC-AGG-ID: lMYQWpJ4O4OyNhBZn4ZmJQ_1739810437 From: Albert Esteve To: qemu-devel@nongnu.org Cc: slp@redhat.com, stevensd@chromium.org, =?UTF-8?q?Alex=20Benn=C3=A9e?= , Stefano Garzarella , stefanha@redhat.com, david@redhat.com, hi@alyssa.is, mst@redhat.com, jasowang@redhat.com, Albert Esteve Subject: [PATCH v4 3/9] vhost_user.rst: Add SHMEM_MAP/_UNMAP to spec Date: Mon, 17 Feb 2025 17:40:06 +0100 Message-ID: <20250217164012.246727-4-aesteve@redhat.com> In-Reply-To: <20250217164012.246727-1-aesteve@redhat.com> References: <20250217164012.246727-1-aesteve@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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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 | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 436a94c0ee..c15d6ac467 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -375,6 +375,7 @@ 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 +1058,7 @@ 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 +1867,38 @@ 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``. A reply is + generated indicating whether mapping succeeded. + + Mapping over an already existing map is not allowed and request shall fa= il. + 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-mmap a given range (``shm_offset``, ``len``) in the + 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 2.48.1