modesetting has a sort of broken concept of getting the cursor dimensions since 1f41320e1c, which causes issues on virtual machines and older AMD hardware. Our solution is to use SIZE_HINTS which is available in i915 since 2023 otherwise fallback to getting the cursor size provided by the driver, if a driver wants to have a more optimal cursor size, it is more than welcome to implement SIZE_HINTS in it's DRM interface.
Taken from my own fork of Xorg.
v2: Fix some bugs in the implemenation.