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Tue, 18 Feb 2025 11:00:20 +0000 (UTC) Received: from localhost (unknown [10.2.16.24]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 5AB9D1800361; Tue, 18 Feb 2025 11:00:19 +0000 (UTC) Date: Tue, 18 Feb 2025 19:00:17 +0800 From: Stefan Hajnoczi To: Albert Esteve Cc: qemu-devel@nongnu.org, slp@redhat.com, stevensd@chromium.org, Alex =?iso-8859-1?Q?Benn=E9e?= , Stefano Garzarella , david@redhat.com, hi@alyssa.is, mst@redhat.com, jasowang@redhat.com Subject: Re: [PATCH v4 9/9] vhost_user.rst: Add MEM_READ/WRITE messages Message-ID: <20250218110017.GM10767@fedora> References: <20250217164012.246727-1-aesteve@redhat.com> <20250217164012.246727-10-aesteve@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lsn8N0RWa2sb4g8M" Content-Disposition: inline In-Reply-To: <20250217164012.246727-10-aesteve@redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@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_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --lsn8N0RWa2sb4g8M Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Feb 17, 2025 at 05:40:12PM +0100, Albert Esteve wrote: > Add MEM_READ/WRITE request to the vhost-user > spec documentation. >=20 > Signed-off-by: Albert Esteve > --- > docs/interop/vhost-user.rst | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) >=20 > 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 th= e following struct: > VhostUserTransferDeviceState transfer_state; > VhostUserMMap mmap; > VhostUserShMemConfig shmem; > + VhostUserMemRWMsg mem_rw; Is this struct defined anywhere in the spec? > }; > } 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 >=20 --lsn8N0RWa2sb4g8M Content-Type: application/pgp-signature; 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