From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus Date: Mon, 20 Jan 2020 15:50:01 +0800 Message-ID: References: <20200116124231.20253-1-jasowang@redhat.com> <20200116124231.20253-4-jasowang@redhat.com> <20200116152209.GH20978@mellanox.com> <03cfbcc2-fef0-c9d8-0b08-798b2a293b8c@redhat.com> <20200117135435.GU20978@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20200117135435.GU20978@mellanox.com> Content-Language: en-US Sender: kvm-owner@vger.kernel.org To: Jason Gunthorpe Cc: "mst@redhat.com" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , "netdev@vger.kernel.org" , "tiwei.bie@intel.com" , "maxime.coquelin@redhat.com" , "cunming.liang@intel.com" , "zhihong.wang@intel.com" , "rob.miller@broadcom.com" , "xiao.w.wang@intel.com" , "haotian.wang@sifive.com" , "lingshan.zhu@intel.com" , "eperezma@redhat.com" , "lulu@redhat.com" List-Id: virtualization@lists.linuxfoundation.org On 2020/1/17 =E4=B8=8B=E5=8D=889:54, Jason Gunthorpe wrote: > On Fri, Jan 17, 2020 at 11:03:12AM +0800, Jason Wang wrote: >> On 2020/1/16 =E4=B8=8B=E5=8D=8811:22, Jason Gunthorpe wrote: >>> On Thu, Jan 16, 2020 at 08:42:29PM +0800, Jason Wang wrote: >>>> vDPA device is a device that uses a datapath which complies with the >>>> virtio specifications with vendor specific control path. vDPA device= s >>>> can be both physically located on the hardware or emulated by >>>> software. vDPA hardware devices are usually implemented through PCIE >>>> with the following types: >>>> >>>> - PF (Physical Function) - A single Physical Function >>>> - VF (Virtual Function) - Device that supports single root I/O >>>> virtualization (SR-IOV). Its Virtual Function (VF) represents a >>>> virtualized instance of the device that can be assigned to diffe= rent >>>> partitions >>>> - VDEV (Virtual Device) - With technologies such as Intel Scalable >>>> IOV, a virtual device composed by host OS utilizing one or more >>>> ADIs. >>>> - SF (Sub function) - Vendor specific interface to slice the Physica= l >>>> Function to multiple sub functions that can be assigned to diffe= rent >>>> partitions as virtual devices. >>> I really hope we don't end up with two different ways to spell this >>> same thing. >> I think you meant ADI vs SF. It looks to me that ADI is limited to the= scope >> of scalable IOV but SF not. > I think if one looks carefully you'd find that SF and ADI are using > very similar techiniques. For instance we'd also like to use the code > reorg of the MSIX vector setup with SFs that Intel is calling IMS. > > Really SIOV is simply a bundle of pre-existing stuff under a tidy > name, whatever code skeleton we come up with for SFs should be re-used > for ADI. Ok, but do you prefer to mention ADI only for the next version? > >>> Shouldn't there be a device/driver matching process of some kind? >> >> The question is what do we want do match here. >> >> 1) "virtio" vs "vhost", I implemented matching method for this in mdev >> series, but it looks unnecessary for vDPA device driver to know about = this. >> Anyway we can use sysfs driver bind/unbind to switch drivers >> 2) virtio device id and vendor id. I'm not sure we need this consider = the >> two drivers so far (virtio/vhost) are all bus drivers. > As we seem to be contemplating some dynamic creation of vdpa devices I > think upon creation time it should be specified what mode they should > run it and then all driver binding and autoloading should happen > automatically. Telling the user to bind/unbind is a very poor > experience. > > Jason Ok, I will add the type (virtio vs vhost) and driver matching method back= . Thanks