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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1739810535; 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=rrOHEASD5ETftMjnPAsJydFA8UyEJ3azffjK7xeCoRc=; b=CH2Z1DMfPwMUgMpbnoUTHU0NjABD2fOR6NnI7fZfqRqv7jD1xqrUgZbmlBUZ/5YxyNFFDF k/TuogsPG97Nv1UFLgYYDe1DeEENkzByRgHnAko+5pkwVOyITpZl+tsiMS5OC7YDjdUzBM DfkZnsF9JQXXYuJne6FR2fZ7QVIA09M= X-MC-Unique: Ghl4AiDdM6Wz8Gl_v4r54Q-1 X-Mimecast-MFC-AGG-ID: Ghl4AiDdM6Wz8Gl_v4r54Q_1739810466 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 9/9] vhost_user.rst: Add MEM_READ/WRITE messages Date: Mon, 17 Feb 2025 17:40:12 +0100 Message-ID: <20250217164012.246727-10-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 MEM_READ/WRITE request to the vhost-user spec documentation. Signed-off-by: Albert Esteve --- docs/interop/vhost-user.rst | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 96156f1900..9f7a2c4cf7 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -391,6 +391,7 @@ In QEMU the vhost-user message is implemented with the = following struct: VhostUserTransferDeviceState transfer_state; VhostUserMMap mmap; VhostUserShMemConfig shmem; + VhostUserMemRWMsg mem_rw; }; } QEMU_PACKED VhostUserMsg; =20 @@ -1938,6 +1939,38 @@ is sent by the front-end. given range shall correspond to the entirety of a valid mapped region. A reply is generated indicating whether unmapping succeeded. =20 +``VHOST_USER_BACKEND_MEM_READ`` + :id: 11 + :equivalent ioctl: N/A + :request payload: ``struct VhostUserMemRWMsg`` + :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 + read a memory region that has failed to resolve a translation due to an + incomplete memory table, after another device called + ``VHOST_USER_BACKEND_SHMEM_MAP`` for the same region on a shared + descriptor file. + + This mechanism works as a fallback for resolving those memory + accesses and ensure that DMA works with Shared Memory Regions. + +``VHOST_USER_BACKEND_MEM_WRITE`` + :id: 12 + :equivalent ioctl: N/A + :request payload: ``struct VhostUserMemRWMsg`` + :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 + write a memory region that has failed due to resolve a translation an + incomplete memory table after another device called + ``VHOST_USER_BACKEND_SHMEM_MAP`` for the same region on a shared + descriptor file. + + This mechanism works as a fallback for resolving those memory + accesses and ensure that DMA works with Shared Memory Regions. + .. _reply_ack: =20 VHOST_USER_PROTOCOL_F_REPLY_ACK --=20 2.48.1