[vfio-users] Mediated device interface + nvidia

[Alex Williamson]

On Thu, 15 Dec 2016 17:30:32 +0000
Zir Blazer <zir_blazer at hotmail.com> wrote:

> You WILL see it on consumer grade GPUs on a massive scale, as any Intel platform with a Broadwell or Skylake Processor with IGP will have access to Intel GVT-g. While the raw power of the Intel IGPs is a fraction of a bigger Radeon or GeForce, they are rather on par with features, and as long that you don't need a bigger GPU performance (Modern games, high resolutions or high quality), it will be more than enough for the purpose of sharing one GPU among multiple VMs.
> On Desktop systems, the absolutely most simple setup will be to use the Intel IGP for host and other 3 VMs with vGPU in one Monitor, and VGA Passthrough of a big Video Card for your Windows gaming VM in another Monitor.
> 
> XenGT also supported Haswell IGPs, but when the Intel devs started working in KVMGT, they only worked on Broadwell+ and left Haswell out. I was disappointed by that since I have a Haswell Processor. Maybe someone will eventually want to port XenGT Haswell support to KVMGT, as most of the code should be done...
> 
> 
> What I don't know is how much work upstreaming KVMGT is left. They already mainlined the guest Linux vGPU Drivers many Kernels ago, and also did it with Windows, too. With this, they are getting in the host Linux Drivers for GPU Virtualization support. I THINK they had already added the required code to QEMU, too, but I'm not 100% sure about that since I can't find a clear changelog, they are just talking about IGD Passthrough, which is not the same.
> Regardless, chances are that in around 3-4 months with Linux Kernel 4.10 and next QEMU, iGVT-g is going for the masses. I have been waiting for this moment since I first heared about XenGT THREE YEARS AGO...

One of the advantages of the vfio mediated device interface is that API
exposed to the user, and thus QEMU, is identical to a directly assigned
device.  Therefore AFAIK, there are no QEMU changes necessary for
KVMGT.  This guide still indicates support for 4th generation (aka
Haswell), but I don't know how accurate it is:

https://github.com/01org/gvt-linux/wiki/GVTg_Setup_Guide

Thanks,
Alex