drm/i915: num_pd_pages/num_pd_entries isn't useful

These values are never quite useful for dynamic allocations of the page
tables. Getting rid of them will help prevent later confusion.

v2: Updated to use unmap_and_free_pd functions.
v3: Updated gen8_ppgtt_free after teardown logic was removed.
v4: Rebase after s/page_tables/page_table/.
v5: Keep allocating all page directories in GEN8+ systems with less
than 4GB of memory. Updated gen6_for_all_pdes.
v6: Prevent (harmless) out of range access in gen6_for_all_pdes.

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/i915_debugfs.c

@@ -2188,8 +2188,6 @@ static void gen8_ppgtt_info(struct seq_file *m, struct drm_device *dev)
 	if (!ppgtt)
 		return;
 
-	seq_printf(m, "Page directories: %d\n", ppgtt->num_pd_pages);
-	seq_printf(m, "Page tables: %d\n", ppgtt->num_pd_entries);
 	for_each_ring(ring, dev_priv, unused) {
 		seq_printf(m, "%s\n", ring->name);
 		for (i = 0; i < 4; i++) {

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -657,7 +657,7 @@ static void gen8_ppgtt_free(struct i915_hw_ppgtt *ppgtt)
 {
 	int i;
 
-	for (i = 0; i < ppgtt->num_pd_pages; i++) {
+	for (i = 0; i < GEN8_LEGACY_PDPES; i++) {
 		if (WARN_ON(!ppgtt->pdp.page_directory[i]))
 			continue;
 
@@ -737,34 +737,26 @@ static int gen8_ppgtt_alloc_page_directories(struct i915_page_directory_pointer
 
 		gen8_initialize_pd(&ppgtt->base,
 				   ppgtt->pdp.page_directory[pdpe]);
-		ppgtt->num_pd_pages++;
 	}
 
 	/* XXX: Still alloc all page directories in systems with less than
 	 * 4GB of memory. This won't be needed after a subsequent patch.
 	 */
-	while (ppgtt->num_pd_pages < GEN8_LEGACY_PDPES) {
-		ppgtt->pdp.page_directory[ppgtt->num_pd_pages] = alloc_pd_single();
-		if (IS_ERR(ppgtt->pdp.page_directory[ppgtt->num_pd_pages]))
+	while (pdpe < GEN8_LEGACY_PDPES) {
+		ppgtt->pdp.page_directory[pdpe] = alloc_pd_single();
+		if (IS_ERR(ppgtt->pdp.page_directory[pdpe]))
 			goto unwind_out;
 
 		gen8_initialize_pd(&ppgtt->base,
-				   ppgtt->pdp.page_directory[ppgtt->num_pd_pages]);
+				   ppgtt->pdp.page_directory[pdpe]);
 		pdpe++;
-		ppgtt->num_pd_pages++;
 	}
 
-	BUG_ON(ppgtt->num_pd_pages > GEN8_LEGACY_PDPES);
-
 	return 0;
 
 unwind_out:
-	while (pdpe--) {
+	while (pdpe--)
 		unmap_and_free_pd(ppgtt->pdp.page_directory[pdpe]);
-		ppgtt->num_pd_pages--;
-	}
-
-	WARN_ON(ppgtt->num_pd_pages);
 
 	return -ENOMEM;
 }
@@ -787,8 +779,6 @@ static int gen8_ppgtt_alloc(struct i915_hw_ppgtt *ppgtt,
 						&ppgtt->base);
 		if (ret)
 			goto err_out;
-
-		ppgtt->num_pd_entries += I915_PDES;
 	}
 
 	/* XXX: We allocated all page directories in systems with less than
@@ -801,12 +791,9 @@ static int gen8_ppgtt_alloc(struct i915_hw_ppgtt *ppgtt,
 		if (ret)
 			goto err_out;
 
-		ppgtt->num_pd_entries += I915_PDES;
 		pdpe++;
 	}
 
-	WARN_ON(pdpe > ppgtt->num_pd_pages);
-
 	return 0;
 
 err_out:
@@ -868,8 +855,6 @@ static int gen8_ppgtt_setup_page_tables(struct i915_hw_ppgtt *ppgtt,
  */
 static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
 {
-	const int max_pdp = DIV_ROUND_UP(size, 1 << 30);
-	const int min_pt_pages = I915_PDES * max_pdp;
 	int i, j, ret;
 
 	if (size % (1<<30))
@@ -940,16 +925,7 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
 	ppgtt->base.insert_entries = gen8_ppgtt_insert_entries;
 	ppgtt->base.cleanup = gen8_ppgtt_cleanup;
 
-	/* Set all ptes to a valid scratch page. Also above requested space */
-	ppgtt->base.clear_range(&ppgtt->base, 0,
-				ppgtt->num_pd_pages * GEN8_PTES * PAGE_SIZE,
-				true);
-
-	DRM_DEBUG_DRIVER("Allocated %d pages for page directories (%d wasted)\n",
-			 ppgtt->num_pd_pages, ppgtt->num_pd_pages - max_pdp);
-	DRM_DEBUG_DRIVER("Allocated %d pages for page tables (%lld wasted)\n",
-			 ppgtt->num_pd_entries,
-			 (ppgtt->num_pd_entries - min_pt_pages) + size % (1<<30));
+	ppgtt->base.clear_range(&ppgtt->base, 0, ppgtt->base.total, true);
 	return 0;
 
 bail:
@@ -959,26 +935,20 @@ bail:
 
 static void gen6_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m)
 {
-	struct drm_i915_private *dev_priv = ppgtt->base.dev->dev_private;
 	struct i915_address_space *vm = &ppgtt->base;
-	gen6_pte_t __iomem *pd_addr;
+	struct i915_page_table *unused;
 	gen6_pte_t scratch_pte;
 	uint32_t pd_entry;
-	int pte, pde;
+	uint32_t  pte, pde, temp;
+	uint32_t start = ppgtt->base.start, length = ppgtt->base.total;
 
 	scratch_pte = vm->pte_encode(vm->scratch.addr, I915_CACHE_LLC, true, 0);
 
-	pd_addr = (gen6_pte_t __iomem *)dev_priv->gtt.gsm +
-		ppgtt->pd.pd_offset / sizeof(gen6_pte_t);
-
-	seq_printf(m, "  VM %p (pd_offset %x-%x):\n", vm,
-		   ppgtt->pd.pd_offset,
-		   ppgtt->pd.pd_offset + ppgtt->num_pd_entries);
-	for (pde = 0; pde < ppgtt->num_pd_entries; pde++) {
+	gen6_for_each_pde(unused, &ppgtt->pd, start, length, temp, pde) {
 		u32 expected;
 		gen6_pte_t *pt_vaddr;
 		dma_addr_t pt_addr = ppgtt->pd.page_table[pde]->daddr;
-		pd_entry = readl(pd_addr + pde);
+		pd_entry = readl(ppgtt->pd_addr + pde);
 		expected = (GEN6_PDE_ADDR_ENCODE(pt_addr) | GEN6_PDE_VALID);
 
 		if (pd_entry != expected)
@@ -1376,13 +1346,12 @@ unwind_out:
 
 static void gen6_ppgtt_free(struct i915_hw_ppgtt *ppgtt)
 {
-	int i;
-
-	for (i = 0; i < ppgtt->num_pd_entries; i++) {
-		struct i915_page_table *pt = ppgtt->pd.page_table[i];
+	struct i915_page_table *pt;
+	uint32_t pde;
 
+	gen6_for_all_pdes(pt, ppgtt, pde) {
 		if (pt != ppgtt->scratch_pt)
-			unmap_and_free_pt(ppgtt->pd.page_table[i], ppgtt->base.dev);
+			unmap_and_free_pt(pt, ppgtt->base.dev);
 	}
 
 	unmap_and_free_pt(ppgtt->scratch_pt, ppgtt->base.dev);
@@ -1443,7 +1412,6 @@ alloc:
 	if (ppgtt->node.start < dev_priv->gtt.mappable_end)
 		DRM_DEBUG("Forced to use aperture for PDEs\n");
 
-	ppgtt->num_pd_entries = I915_PDES;
 	return 0;
 
 err_out:
@@ -1491,7 +1459,7 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt, bool aliasing)
 
 	if (aliasing) {
 		/* preallocate all pts */
-		ret = alloc_pt_range(&ppgtt->pd, 0, ppgtt->num_pd_entries,
+		ret = alloc_pt_range(&ppgtt->pd, 0, I915_PDES,
 				ppgtt->base.dev);
 
 		if (ret) {
@@ -1505,7 +1473,7 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt, bool aliasing)
 	ppgtt->base.insert_entries = gen6_ppgtt_insert_entries;
 	ppgtt->base.cleanup = gen6_ppgtt_cleanup;
 	ppgtt->base.start = 0;
-	ppgtt->base.total = ppgtt->num_pd_entries * GEN6_PTES * PAGE_SIZE;
+	ppgtt->base.total = I915_PDES * GEN6_PTES * PAGE_SIZE;
 	ppgtt->debug_dump = gen6_dump_ppgtt;
 
 	ppgtt->pd.pd_offset =

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -314,8 +314,6 @@ struct i915_hw_ppgtt {
 	struct kref ref;
 	struct drm_mm_node node;
 	unsigned long pd_dirty_rings;
-	unsigned num_pd_entries;
-	unsigned num_pd_pages; /* gen8+ */
 	union {
 		struct i915_page_directory_pointer pdp;
 		struct i915_page_directory pd;
@@ -350,6 +348,11 @@ struct i915_hw_ppgtt {
 	     temp = min_t(unsigned, temp, length), \
 	     start += temp, length -= temp)
 
+#define gen6_for_all_pdes(pt, ppgtt, iter)  \
+	for (iter = 0;		\
+	     pt = ppgtt->pd.page_table[iter], iter < I915_PDES;	\
+	     iter++)
+
 static inline uint32_t i915_pte_index(uint64_t address, uint32_t pde_shift)
 {
 	const uint32_t mask = NUM_PTE(pde_shift) - 1;