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Mon, 25 May 2020 08:34:05 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxkUYDVkbO7r+CbXp20FY/f2rIETMYoQ6qzpntGzsS2rGKLGbp/g4mM3zIm9uoOi+ZPsITeOyGO/42AdI1RxtA= X-Received: by 2002:a63:1617:: with SMTP id w23mr5504541pgl.248.1590420845404; Mon, 25 May 2020 08:34:05 -0700 (PDT) MIME-Version: 1.0 References: <20200508163218.22592-1-lulu@redhat.com> <20200508163218.22592-6-lulu@redhat.com> <20200521124032.GH251811@stefanha-x1.localdomain> In-Reply-To: <20200521124032.GH251811@stefanha-x1.localdomain> From: Cindy Lu Date: Mon, 25 May 2020 23:33:54 +0800 Message-ID: Subject: Re: [RFC v2 5/9] vhost-vdpa: implement vhost-vdpa backend To: Stefan Hajnoczi X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=207.211.31.120; envelope-from=lulu@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/25 08:28:26 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: rdunlap@infradead.org, Michael Tsirkin , mhabets@solarflare.com, qemu-devel@nongnu.org, rob.miller@broadcom.com, saugatm@xilinx.com, Markus Armbruster , hch@infradead.org, Eugenio Perez Martin , jgg@mellanox.com, Jason Wang , Shahaf Shuler , kevin.tian@intel.com, parav@mellanox.com, vmireyno@marvell.com, "Liang, Cunming" , gdawar@xilinx.com, jiri@mellanox.com, xiao.w.wang@intel.com, Stefan Hajnoczi , "Wang, Zhihong" , Maxime Coquelin , Tiwei Bie , Ariel Adam , Cornelia Huck , hanand@xilinx.com, "Zhu, Lingshan" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, May 21, 2020 at 8:40 PM Stefan Hajnoczi wrote: > > On Sat, May 09, 2020 at 12:32:14AM +0800, Cindy Lu wrote: > > From: Tiwei Bie > > > > Currently we have 2 types of vhost backends in QEMU: vhost kernel and > > vhost-user. The above patch provides a generic device for vDPA purpose, > > this vDPA device exposes to user space a non-vendor-specific configuration > > interface for setting up a vhost HW accelerator, this patch set introduces > > a third vhost backend called vhost-vdpa based on the vDPA interface. > > > > Vhost-vdpa usage: > > > > qemu-system-x86_64 -cpu host -enable-kvm \ > > ...... > > -netdev type=vhost-vdpa,vhostdev=/dev/vhost-vdpa-id,id=vhost-vdpa0 \ > > -device virtio-net-pci,netdev=vhost-vdpa0,page-per-vq=on \ > > I haven't looked at vDPA in depth. What is different here compared to > the existing vhost-backend.c kernel backend? > > It seems to be making the same ioctls calls so I wonder if it makes > sense to share the vhost-backend.c kernel code? > > Stefan Hi Stefan, Sorry for the late reply and Thanks for these suggestions. I think the most difference between vhost kernel and vdpa is vdpa depends on a real hardware. The point is that vDPA devices work as a virtio device, but vhost-vdpa qemu must present a vhost-like device in qemu vhost layer. The ioctl calls are similar with vhost-backend.c now, but after more and more NIC support vdpa. The difference between vhost-backend.c and vpda will become more and more big. It will make the code complicated to share the code with kernel code. Thanks Cindy