From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 9 Aug 2022 05:33:15 -0400 From: "Michael S. Tsirkin" Subject: Re: [virtio-comment] [PATCH V3 RESEND 1/4] Introduce virito transport virtqueue Message-ID: <20220809053032-mutt-send-email-mst@kernel.org> References: <20220805095343.486546-1-lingshan.zhu@intel.com> <20220805095343.486546-2-lingshan.zhu@intel.com> <1f82b84c-db9d-69c1-6a41-a4573036ce0c@intel.com> <20220809050941-mutt-send-email-mst@kernel.org> <0bc52b68-0e7c-4324-c7b5-8867561540a4@intel.com> MIME-Version: 1.0 In-Reply-To: <0bc52b68-0e7c-4324-c7b5-8867561540a4@intel.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline To: "Zhu, Lingshan" Cc: Jason Wang , Cornelia Huck , Stefano Garzarella , Stefan Hajnoczi , nrupal.jani@intel.com, "Uminski, Piotr" , hang.yuan@intel.com, virtio-comment@lists.oasis-open.org List-ID: On Tue, Aug 09, 2022 at 05:28:26PM +0800, Zhu, Lingshan wrote: > > > On 8/9/2022 5:21 PM, Jason Wang wrote: > > On Tue, Aug 9, 2022 at 5:19 PM Zhu, Lingshan wrote: > > > > > > > > > On 8/9/2022 5:12 PM, Michael S. Tsirkin wrote: > > > > On Tue, Aug 09, 2022 at 04:36:43PM +0800, Zhu, Lingshan wrote: > > > > > > > + > > > > > > > +A device that offers feature bit VIRTIO_F_TRANSPT_VQ and a transport virtqueue is a management device. > > > > > > > +It processes the commands through the transport virtqueue commands. > > > > > > I think we need to be verbose here, e.g what did those transport > > > > > > virtqueue commands do? What's the relationship between management > > > > > > device and managed device? > > > > > I will add an overview of the transport virtqueue commands here, and a > > > > > description of the relationship in the "managed device" section. > > > > Transport is fine but management of devices is clearly something > > > > nvidia's patches do. So I think it's best to reuse the concept of device > > > > groups for this, from Max's patchset. Let's not replicate that work at > > > > least. I promised Max to help a bit with wording so I'll soon send a > > > > revision of his patchset, the generic part about device group > > > > from which you should be able to reuse. > > > Of course, it is possible to add the device groups in this series for sure. > > > > > > What I don't understand is: what kind of commands against a device > > > group? Destroy all? > > > And normally a parent device only support one kind of devices, like a > > > SRIOV capable > > > virtio-net PF only supports virtio-net VFs on it, and maybe there will > > > not be > > > a device support both SIOV and SRIOV, it is complex in the HW > > > implementation. > > For having backward compatibility? (E.g for platforms that don't support SIOV) > > > > Thanks > If not a device model like SIOV which does not have a dedicated physical > transport layer, > the question would be: Why do we need a side channel for a VF? This looks > conflicts with > VF provisioning and virtio-spec definitions. E.g, why allow changing MSI in > the flight > outside the guest control? > > Thanks, > Zhu Lingshan MSI is a weird one, seeing that it's an nvidia specific extension to the pci spec. A better example in the latest version is controlling device features or config space for example. That part is somewhat similar to what you guys have with SIOV. -- MST