mmMC_VM_FB_LOCATION_BASE
WREG32_SOC15(GC, 0, mmMC_VM_FB_LOCATION_BASE, 0x00FFFFFF);
WREG32_SOC15(MMHUB, 0, mmMC_VM_FB_LOCATION_BASE,
u64 base = RREG32_SOC15(MMHUB, 0, mmMC_VM_FB_LOCATION_BASE);