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Tue, 18 Feb 2025 04:51:08 -0800 (PST) X-Google-Smtp-Source: AGHT+IH6BP9I/JWOp93ZM6EXZbLVx7xFRe2L2x8tle/ypQn7aft8yzmFk0FuI8pEgkaQGk9UL7KNnkw5FMXnrCC5QGY= X-Received: by 2002:a17:90b:1e05:b0:2fa:1e3e:9be5 with SMTP id 98e67ed59e1d1-2fc407915edmr25809354a91.0.1739883067745; Tue, 18 Feb 2025 04:51:07 -0800 (PST) MIME-Version: 1.0 References: <20250217164012.246727-1-aesteve@redhat.com> <20250217164012.246727-10-aesteve@redhat.com> <20250218110017.GM10767@fedora> In-Reply-To: <20250218110017.GM10767@fedora> From: Albert Esteve Date: Tue, 18 Feb 2025 13:50:55 +0100 X-Gm-Features: AWEUYZkEKLLYUy2ki-twyEHWP-5_CNrrveISawGEPY7FgRdt24tvnqwQ_2C_cC4 Message-ID: Subject: Re: [PATCH v4 9/9] vhost_user.rst: Add MEM_READ/WRITE messages To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, slp@redhat.com, stevensd@chromium.org, =?UTF-8?B?QWxleCBCZW5uw6ll?= , Stefano Garzarella , david@redhat.com, hi@alyssa.is, mst@redhat.com, jasowang@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.423, 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 On Tue, Feb 18, 2025 at 12:00=E2=80=AFPM Stefan Hajnoczi wrote: > > On Mon, Feb 17, 2025 at 05:40:12PM +0100, Albert Esteve wrote: > > 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; > > Is this struct defined anywhere in the spec? Ah, no, right. I did not see all the other structs defined, so I assumed some were just to be found in the code. But then it wouldn't serve as a specification... I realized I was not looking at the right section. VhostUserMMap is also missing, then. I will add them in the next iteration in their respective commits. > > > }; > > } QEMU_PACKED VhostUserMsg; > > > > @@ -1938,6 +1939,38 @@ is sent by the front-end. > > given range shall correspond to the entirety of a valid mapped regio= n. > > A reply is generated indicating whether unmapping succeeded. > > > > +``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 backen= ds 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 backen= ds to > > + write a memory region that has failed due to resolve a translation a= n > > + 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: > > > > VHOST_USER_PROTOCOL_F_REPLY_ACK > > -- > > 2.48.1 > >