After using iGVT-g guest and suspending system, GPU clock is locked at 100 MHz

[Leonardo Müller]

It was observed that after using an iGVT-g guest and suspending the system, the GPU clock is locked to 100 MHz on wake up. Normally, the GPU would idle at 300 MHz and go up to 1000 MHz when required, so the GPU starts operating at only 1/3 of the normal idle clock and 1/10 of the maximum clock.

A kernel WARNING appears on wake up, being something like:

[ 1492.886048] WARNING: CPU: 0 PID: 8653 at /build/linux-hwe-edge-ixgf89/linux-hwe-edge-5.3.0/drivers/gpu/drm/i915/gem/i915_gem_pm.c:248 i915_gem_resume+0xc0/0xd0 [i915]

The GPU is an Intel HD Graphics 520, the processor is an Intel Core i3-6100U. This bug is already fixed on drm-tip.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-5.3.0-23-generic 5.3.0-23.25~18.04.1
ProcVersionSignature: Ubuntu 5.3.0-23.25~18.04.1-generic 5.3.7
Uname: Linux 5.3.0-23-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
CurrentDesktop: XFCE
Date: Sun Nov 17 21:49:28 2019
InstallationDate: Installed on 2017-06-13 (887 days ago)
InstallationMedia: Xubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: linux-signed-hwe-edge
UpgradeStatus: Upgraded to bionic on 2017-10-20 (759 days ago)