Tutorial for passing through a Nvidia RTX graphics card to a Windows 10 virtual machine using a modified VBIOS
Recently I replaced my old NEC MultiSync 2690 HD screen for a HP DreamColor wide gamut screen with a 2560 x 1440 pixel resolution. The Nvidia GTX 970 GPU I used, though still perfectly capable at HD resolution, is likely to get challenged by higher resolutions. Moreover, the new Nvidia Studio driver doesn’t support models before the Geforce 1000 series, and I do want the 30 bpp (bit-per-pixel) support that this driver provides. Time for an upgrade – the Gigabyte RTX 2070 Super GPU.
I’ve already written a detailed tutorial on Windows 10 kvm VGA passthrough based on QEMU version 2.11. Years have passed and recent distributions like Ubuntu 20.04, Linux Mint 20, or Manjaro come with QEMU 4.0, 4.2 or 5.1.
It wasn’t easy this time. Don’t get me wrong – the VFIO passthrough part, though challenging in some ways, went quite well. All in all I’m pleased now with the results. Here the Passmark 9.0 benchmark as uploaded onto their database (for more details, click the frame below):
I’ve been contemplating a PC upgrade for more than a year (see my post here). At first I considered staying with Intel and getting an i9-9900K CPU with integrated GPU on a Z390 motherboard.
Along came the AMD Ryzen 9 3900X that topped the benchmarks, including the Adobe Lightroom and Photoshop benchmarks (to be precise, it ranked #4 in the Adobe Lightroom benchmark, and a narrow #1 in the Adobe Photoshop benchmark). These good news about the AMD Ryzen 3900X were soon followed by reports about BIOS issues and VFIO incompatibility. At the very least, it looked like VGA passthrough was more challenging.
A year ago I wrote about the 2D graphics performance impact of the Windows 10 (1803) update inside a virtual machine. As it turned out, the performance impact was related to the Spectre vulnerability patch that Microsoft had introduced. However, the same patch had practically no performance impact on a Windows 10 bare-metal installation.
When running a VM with GPU passthrough, that GPU should be bound to the VFIO driver. To make this happen, we need to prevent the regular graphics driver from binding to the passthrough GPU and instead bind the vfio-pci driver.
Qemu/kvm provides you with a plethora of ways to configure your storage devices. Yet no other type of device shows such a variance in its performance, with disk I/O throughput anywhere from stellar to abysmal using the very same hardware.