drm/i915/bdw: HW context support

BDW context sizes varies a bit.

v2: Squash in fixup for the hw context size from Ben.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net> (v1)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_context.c

@@ -117,6 +117,9 @@ static int get_context_size(struct drm_device *dev)
 		else
 			ret = GEN7_CXT_TOTAL_SIZE(reg) * 64;
 		break;
+	case 8:
+		ret = GEN8_CXT_TOTAL_SIZE;
+		break;
 	default:
 		BUG();
 	}

drivers/gpu/drm/i915/i915_reg.h

@@ -1822,6 +1822,9 @@
  * on HSW) - so the final size is 66944 bytes, which rounds to 17 pages.
  */
 #define HSW_CXT_TOTAL_SIZE		(17 * PAGE_SIZE)
+/* Same as Haswell, but 72064 bytes now. */
+#define GEN8_CXT_TOTAL_SIZE		(18 * PAGE_SIZE)
+
 
 #define VLV_CLK_CTL2			0x101104
 #define   CLK_CTL2_CZCOUNT_30NS_SHIFT	28