GGTT invalidation issues

https://lore.kernel.org/all/Y9hw0sSC58B32yPg@mdroper-desk1.amr.corp.intel.com/

GFX_FLSH_CNTL_GEN6.reg not present in newer platforms. and MTL Media GT not invalidated.

+void xe_ggtt_invalidate(struct xe_gt *gt)
+{

• /* TODO: vfunc for GuC vs. non-GuC */
• /* TODO: i915 makes comments about this being uncached and
• • therefore flushing WC buffers. Is that really true here?
• */
• xe_mmio_write32(gt, GFX_FLSH_CNTL_GEN6.reg, GFX_FLSH_CNTL_EN);

This register went away in Xe_HP; we shouldn't be trying to write it on
newer platforms. I'm not sure if there's an equivalent register located
somewhere else now or not.

and

+void xe_ggtt_map_bo(struct xe_ggtt *ggtt, struct xe_bo *bo)
+{

• u64 start = bo->ggtt_node.start;
• u64 offset, pte;
• for (offset = 0; offset < bo->size; offset += GEN8_PAGE_SIZE) {

•       pte = xe_ggtt_pte_encode(bo, offset);                                                                                                                                                                                          

•       xe_ggtt_set_pte(ggtt, start + offset, pte);                                                                                                                                                                                    

• }
• xe_ggtt_invalidate(ggtt->gt);

The GGTT is shared by two GTs on a platform like MTL; we only seem to be
invalidating the GuC's TLB for the primary GT here and are overlooking
the media GT.