drm/i915/gen8: Split out mappings

When we do dynamic page table allocations for gen8, we'll need to have
more control over how and when we map page tables, similar to gen6.
In particular, DMA mappings for page directories/tables occur at allocation
time.

This patch adds the functionality and calls it at init, which should
have no functional change.

The PDPEs are still a special case for now. We'll need a function for
that in the future as well.

v2: Handle renamed unmap_and_free_page functions.
v3: Updated after teardown_va logic was removed.
v4: Rebase after s/page_tables/page_table/.
v5: No longer allocate all PDPs in GEN8+ systems with less than 4GB of
memory, and update populate_lr_context to handle this new case (proper
tracking will be added later in the patch series).
v6: Assign lrc page directory pointer addresses using a macro. (Mika)

Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Michel Thierry <michel.thierry@intel.com> (v2+)
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_lrc.c

@@ -188,6 +188,15 @@
 #define GEN8_CTX_FORCE_RESTORE (1<<2)
 #define GEN8_CTX_L3LLC_COHERENT (1<<5)
 #define GEN8_CTX_PRIVILEGE (1<<8)
+
+#define ASSIGN_CTX_PDP(ppgtt, reg_state, n) { \
+	const u64 _addr = ppgtt->pdp.page_directory[n] ? \
+		ppgtt->pdp.page_directory[n]->daddr : \
+		ppgtt->scratch_pd->daddr; \
+	reg_state[CTX_PDP ## n ## _UDW+1] = upper_32_bits(_addr); \
+	reg_state[CTX_PDP ## n ## _LDW+1] = lower_32_bits(_addr); \
+}
+
 enum {
 	ADVANCED_CONTEXT = 0,
 	LEGACY_CONTEXT,
@@ -1755,14 +1764,14 @@ populate_lr_context(struct intel_context *ctx, struct drm_i915_gem_object *ctx_o
 	reg_state[CTX_PDP1_LDW] = GEN8_RING_PDP_LDW(ring, 1);
 	reg_state[CTX_PDP0_UDW] = GEN8_RING_PDP_UDW(ring, 0);
 	reg_state[CTX_PDP0_LDW] = GEN8_RING_PDP_LDW(ring, 0);
-	reg_state[CTX_PDP3_UDW+1] = upper_32_bits(ppgtt->pdp.page_directory[3]->daddr);
-	reg_state[CTX_PDP3_LDW+1] = lower_32_bits(ppgtt->pdp.page_directory[3]->daddr);
-	reg_state[CTX_PDP2_UDW+1] = upper_32_bits(ppgtt->pdp.page_directory[2]->daddr);
-	reg_state[CTX_PDP2_LDW+1] = lower_32_bits(ppgtt->pdp.page_directory[2]->daddr);
-	reg_state[CTX_PDP1_UDW+1] = upper_32_bits(ppgtt->pdp.page_directory[1]->daddr);
-	reg_state[CTX_PDP1_LDW+1] = lower_32_bits(ppgtt->pdp.page_directory[1]->daddr);
-	reg_state[CTX_PDP0_UDW+1] = upper_32_bits(ppgtt->pdp.page_directory[0]->daddr);
-	reg_state[CTX_PDP0_LDW+1] = lower_32_bits(ppgtt->pdp.page_directory[0]->daddr);
+	/* XXX: Systems with less than 4GB of memory do not have
+	 * all PDPs. Proper PDP tracking will be added in a
+	 * subsequent patch.
+	 */
+	ASSIGN_CTX_PDP(ppgtt, reg_state, 3);
+	ASSIGN_CTX_PDP(ppgtt, reg_state, 2);
+	ASSIGN_CTX_PDP(ppgtt, reg_state, 1);
+	ASSIGN_CTX_PDP(ppgtt, reg_state, 0);
 	if (ring->id == RCS) {
 		reg_state[CTX_LRI_HEADER_2] = MI_LOAD_REGISTER_IMM(1);
 		reg_state[CTX_R_PWR_CLK_STATE] = GEN8_R_PWR_CLK_STATE;