Yes, that is correct. The Intel HD Graphics driver for Windows will allocate as much memory as is required. This is limited to half of all available memory. For example, a PC with 8GB will make up to 4GB available for graphics usage, as required.
The only time that Windows users should increase the amount of dedicated graphics memory is if they have a poorly-written game that refuses to run unless it sees that a certain amount of dedicated memory is available. There is no performance advantage to dedicating additional memory for graphics.
Seems we have an issue then because everything through Microsoft will not run correctly irrespective of how much memory you have available if it's not correctly allocated as DVM
Since we can't access through BIOS and changing value in regedit does nothing what can be done.