Re: [libvirt] [Qemu-devel] [RFC v2] libvirt vGPU QEMU integration

On Tue, Sep 20, 2016 at 10:47:53AM +0100, Daniel P. Berrange wrote: > On Tue, Sep 20, 2016 at 02:05:52AM +0530, Kirti Wankhede wrote: > > > > Hi libvirt experts, > > > > Thanks for valuable input on v1 version of RFC. > > > > Quick brief, VFIO based mediated device framework provides a way to > > virtualize their devices without SR-IOV, like NVIDIA vGPU, Intel KVMGT > > and IBM's channel IO. This framework reuses VFIO APIs for all the > > functionalities for mediated devices which are currently being used for > > pass through devices. This framework introduces a set of new sysfs files > > for device creation and its life cycle management. > > > > Here is the summary of discussion on v1: > > 1. Discover mediated device: > > As part of physical device initialization process, vendor driver will > > register their physical devices, which will be used to create virtual > > device (mediated device, aka mdev) to the mediated framework. > > > > Vendor driver should specify mdev_supported_types in directory format. > > This format is class based, for example, display class directory format > > should be as below. We need to define such set for each class of devices > > which would be supported by mediated device framework. > > > > --- mdev_destroy > > --- mdev_supported_types > > |-- 11 > > | |-- create > > | |-- name > > | |-- fb_length > > | |-- resolution > > | |-- heads > > | |-- max_instances > > | |-- params > > | |-- requires_group > > |-- 12 > > | |-- create > > | |-- name > > | |-- fb_length > > | |-- resolution > > | |-- heads > > | |-- max_instances > > | |-- params > > | |-- requires_group > > |-- 13 > > |-- create > > |-- name > > |-- fb_length > > |-- resolution > > |-- heads > > |-- max_instances > > |-- params > > |-- requires_group > > > > > > In the above example directory '11' represents a type id of mdev device. > > 'name', 'fb_length', 'resolution', 'heads', 'max_instance' and > > 'requires_group' would be Read-Only files that vendor would provide to > > describe about that type. > > > > 'create': > > Write-only file. Mandatory. > > Accepts string to create mediated device. > > > > 'name': > > Read-Only file. Mandatory. > > Returns string, the name of that type id. > > Presumably this is a human-targetted title/description of > the device. > > > > > 'fb_length': > > Read-only file. Mandatory. > > Returns <number>{K,M,G}, size of framebuffer. > > > > 'resolution': > > Read-Only file. Mandatory. > > Returns 'hres x vres' format. Maximum supported resolution. > > > > 'heads': > > Read-Only file. Mandatory. > > Returns integer. Number of maximum heads supported. > > None of these should be mandatory as that makes the mdev > useless for non-GPU devices. > > I'd expect to see a 'class' or 'type' attribute in the > directory whcih tells you what kind of mdev it is. A > valid 'class' value would be 'gpu'. The fb_length, > resolution, and heads parameters would only be mandatory > when class==gpu. > Hi Daniel, Here you are proposing to add a class named "gpu", which will make all those gpu related attributes mandatory, which libvirt can allow user to better parse/present a particular mdev configuration? I am just wondering if there is another option that we just make all those attributes that a mdev device can have as optional but still meaningful to libvirt, so libvirt can still parse / recognize them as an class "mdev".