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Tsirkin" To: Weqaar Janjua Cc: qemu-devel@nongnu.org, kraxel@redhat.com, peter.maydell@linaro.org, pierrick.bouvier@oss.qualcomm.com, jasowangio@gmail.com, pbonzini@redhat.com, farosas@suse.de, lvivier@redhat.com, marcel.apfelbaum@gmail.com, peterx@redhat.com, lizhijian@fujitsu.com, odaki@rsg.ci.i.u-tokyo.ac.jp Subject: Re: [PATCH v3 0/6] hw: Add Cnuas virtual devices Message-ID: <20261030191556-mutt-send-email-mst@kernel.org> References: <20260929202358.725310-1-weqaar.janjua@packetfive.com> <20261016153247.1815153-1-weqaar.janjua@packetfive.com> <20261027080746.2468700-1-weqaar.janjua@packetfive.com> <20261027063724-mutt-send-email-mst@kernel.org> <20261029115735.2716219-1-weqaar.janjua@packetfive.com> <20261029134859-mutt-send-email-mst@kernel.org> <20261029194227.2735464-1-weqaar.janjua@packetfive.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261029194227.2735464-1-weqaar.janjua@packetfive.com> Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Oct 29, 2026 at 07:42:24PM +0000, Weqaar Janjua wrote: > On Thu, Oct 29, 2026 at 01:50:11PM -0400, Michael S. Tsirkin wrote: > > Hmm wait a second. I don't understand. Isn't it a physical device you > > are emulating? Why is it using the Red Hat IDs? > > No, it is not a physical device. There is no CnuasNIC or CnuasGPU > hardware; both exist only as virtual devices, the QEMU device models > in this series. Think of CnuasNIC as veth or rxe for RDMA, but > presented to the guest as a PCI device so the full driver, verbs and > RDMA CM path runs unmodified. The Cnuas project (cnuas.io) emulates > the rest of the RDMA subsystem around it, including a RoCEv2 and > InfiniBand switch. CnuasGPU is the same idea for an accelerator. > > The register interfaces are defined by the models themselves and > documented in docs/specs/cnuas-vnic.rst (patch 2) and > docs/specs/cnuasgpu.rst (patch 5), with more detail in the > datasheets at: > > https://cnuas.io/cnuas/docs/datasheets/CnuasNIC_Datasheet/ > https://cnuas.io/cnuas/docs/datasheets/CnuasGPU_Datasheet/ > > So this is the same situation as other QEMU-specific devices in the > 1b36 range, for example pvpanic-pci (1b36:0011) and the emulated UFS > host controller (1b36:0013), which also have upstream Linux drivers. > That is why I asked Gerd for IDs from the QEMU range. If we were to > build hardware, it would use our own PCI vendor ID, not 1b36. > > The "RDMA network adapter" wording may have suggested otherwise. It is > an RoCEv2 adapter in the sense that a Linux guest sees a normal RDMA > device, but the wire side is a socket to a user-space switch process, > not a real NIC. I can make "virtual" more explicit in the commit > messages and docs if that helps. > > Thanks, > > Weqaar I see. Then a simple way for you to get some eyes on this, and a path towards upstreaming, could be to try and add this rdma functionality in the virtio spec. Interface changes might be required during the standardization process. -- MST