xref: /openbmc/linux/drivers/gpu/drm/i915/gt/gen8_ppgtt.c (revision 11a163f2)
1 // SPDX-License-Identifier: MIT
2 /*
3  * Copyright © 2020 Intel Corporation
4  */
5 
6 #include <linux/log2.h>
7 
8 #include "gen8_ppgtt.h"
9 #include "i915_scatterlist.h"
10 #include "i915_trace.h"
11 #include "i915_pvinfo.h"
12 #include "i915_vgpu.h"
13 #include "intel_gt.h"
14 #include "intel_gtt.h"
15 
16 static u64 gen8_pde_encode(const dma_addr_t addr,
17 			   const enum i915_cache_level level)
18 {
19 	u64 pde = addr | _PAGE_PRESENT | _PAGE_RW;
20 
21 	if (level != I915_CACHE_NONE)
22 		pde |= PPAT_CACHED_PDE;
23 	else
24 		pde |= PPAT_UNCACHED;
25 
26 	return pde;
27 }
28 
29 static u64 gen8_pte_encode(dma_addr_t addr,
30 			   enum i915_cache_level level,
31 			   u32 flags)
32 {
33 	gen8_pte_t pte = addr | _PAGE_PRESENT | _PAGE_RW;
34 
35 	if (unlikely(flags & PTE_READ_ONLY))
36 		pte &= ~_PAGE_RW;
37 
38 	switch (level) {
39 	case I915_CACHE_NONE:
40 		pte |= PPAT_UNCACHED;
41 		break;
42 	case I915_CACHE_WT:
43 		pte |= PPAT_DISPLAY_ELLC;
44 		break;
45 	default:
46 		pte |= PPAT_CACHED;
47 		break;
48 	}
49 
50 	return pte;
51 }
52 
53 static void gen8_ppgtt_notify_vgt(struct i915_ppgtt *ppgtt, bool create)
54 {
55 	struct drm_i915_private *i915 = ppgtt->vm.i915;
56 	struct intel_uncore *uncore = ppgtt->vm.gt->uncore;
57 	enum vgt_g2v_type msg;
58 	int i;
59 
60 	if (create)
61 		atomic_inc(px_used(ppgtt->pd)); /* never remove */
62 	else
63 		atomic_dec(px_used(ppgtt->pd));
64 
65 	mutex_lock(&i915->vgpu.lock);
66 
67 	if (i915_vm_is_4lvl(&ppgtt->vm)) {
68 		const u64 daddr = px_dma(ppgtt->pd);
69 
70 		intel_uncore_write(uncore,
71 				   vgtif_reg(pdp[0].lo), lower_32_bits(daddr));
72 		intel_uncore_write(uncore,
73 				   vgtif_reg(pdp[0].hi), upper_32_bits(daddr));
74 
75 		msg = create ?
76 			VGT_G2V_PPGTT_L4_PAGE_TABLE_CREATE :
77 			VGT_G2V_PPGTT_L4_PAGE_TABLE_DESTROY;
78 	} else {
79 		for (i = 0; i < GEN8_3LVL_PDPES; i++) {
80 			const u64 daddr = i915_page_dir_dma_addr(ppgtt, i);
81 
82 			intel_uncore_write(uncore,
83 					   vgtif_reg(pdp[i].lo),
84 					   lower_32_bits(daddr));
85 			intel_uncore_write(uncore,
86 					   vgtif_reg(pdp[i].hi),
87 					   upper_32_bits(daddr));
88 		}
89 
90 		msg = create ?
91 			VGT_G2V_PPGTT_L3_PAGE_TABLE_CREATE :
92 			VGT_G2V_PPGTT_L3_PAGE_TABLE_DESTROY;
93 	}
94 
95 	/* g2v_notify atomically (via hv trap) consumes the message packet. */
96 	intel_uncore_write(uncore, vgtif_reg(g2v_notify), msg);
97 
98 	mutex_unlock(&i915->vgpu.lock);
99 }
100 
101 /* Index shifts into the pagetable are offset by GEN8_PTE_SHIFT [12] */
102 #define GEN8_PAGE_SIZE (SZ_4K) /* page and page-directory sizes are the same */
103 #define GEN8_PTE_SHIFT (ilog2(GEN8_PAGE_SIZE))
104 #define GEN8_PDES (GEN8_PAGE_SIZE / sizeof(u64))
105 #define gen8_pd_shift(lvl) ((lvl) * ilog2(GEN8_PDES))
106 #define gen8_pd_index(i, lvl) i915_pde_index((i), gen8_pd_shift(lvl))
107 #define __gen8_pte_shift(lvl) (GEN8_PTE_SHIFT + gen8_pd_shift(lvl))
108 #define __gen8_pte_index(a, lvl) i915_pde_index((a), __gen8_pte_shift(lvl))
109 
110 #define as_pd(x) container_of((x), typeof(struct i915_page_directory), pt)
111 
112 static inline unsigned int
113 gen8_pd_range(u64 start, u64 end, int lvl, unsigned int *idx)
114 {
115 	const int shift = gen8_pd_shift(lvl);
116 	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
117 
118 	GEM_BUG_ON(start >= end);
119 	end += ~mask >> gen8_pd_shift(1);
120 
121 	*idx = i915_pde_index(start, shift);
122 	if ((start ^ end) & mask)
123 		return GEN8_PDES - *idx;
124 	else
125 		return i915_pde_index(end, shift) - *idx;
126 }
127 
128 static inline bool gen8_pd_contains(u64 start, u64 end, int lvl)
129 {
130 	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
131 
132 	GEM_BUG_ON(start >= end);
133 	return (start ^ end) & mask && (start & ~mask) == 0;
134 }
135 
136 static inline unsigned int gen8_pt_count(u64 start, u64 end)
137 {
138 	GEM_BUG_ON(start >= end);
139 	if ((start ^ end) >> gen8_pd_shift(1))
140 		return GEN8_PDES - (start & (GEN8_PDES - 1));
141 	else
142 		return end - start;
143 }
144 
145 static inline unsigned int
146 gen8_pd_top_count(const struct i915_address_space *vm)
147 {
148 	unsigned int shift = __gen8_pte_shift(vm->top);
149 	return (vm->total + (1ull << shift) - 1) >> shift;
150 }
151 
152 static inline struct i915_page_directory *
153 gen8_pdp_for_page_index(struct i915_address_space * const vm, const u64 idx)
154 {
155 	struct i915_ppgtt * const ppgtt = i915_vm_to_ppgtt(vm);
156 
157 	if (vm->top == 2)
158 		return ppgtt->pd;
159 	else
160 		return i915_pd_entry(ppgtt->pd, gen8_pd_index(idx, vm->top));
161 }
162 
163 static inline struct i915_page_directory *
164 gen8_pdp_for_page_address(struct i915_address_space * const vm, const u64 addr)
165 {
166 	return gen8_pdp_for_page_index(vm, addr >> GEN8_PTE_SHIFT);
167 }
168 
169 static void __gen8_ppgtt_cleanup(struct i915_address_space *vm,
170 				 struct i915_page_directory *pd,
171 				 int count, int lvl)
172 {
173 	if (lvl) {
174 		void **pde = pd->entry;
175 
176 		do {
177 			if (!*pde)
178 				continue;
179 
180 			__gen8_ppgtt_cleanup(vm, *pde, GEN8_PDES, lvl - 1);
181 		} while (pde++, --count);
182 	}
183 
184 	free_px(vm, &pd->pt, lvl);
185 }
186 
187 static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
188 {
189 	struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
190 
191 	if (intel_vgpu_active(vm->i915))
192 		gen8_ppgtt_notify_vgt(ppgtt, false);
193 
194 	__gen8_ppgtt_cleanup(vm, ppgtt->pd, gen8_pd_top_count(vm), vm->top);
195 	free_scratch(vm);
196 }
197 
198 static u64 __gen8_ppgtt_clear(struct i915_address_space * const vm,
199 			      struct i915_page_directory * const pd,
200 			      u64 start, const u64 end, int lvl)
201 {
202 	const struct drm_i915_gem_object * const scratch = vm->scratch[lvl];
203 	unsigned int idx, len;
204 
205 	GEM_BUG_ON(end > vm->total >> GEN8_PTE_SHIFT);
206 
207 	len = gen8_pd_range(start, end, lvl--, &idx);
208 	DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d }\n",
209 	    __func__, vm, lvl + 1, start, end,
210 	    idx, len, atomic_read(px_used(pd)));
211 	GEM_BUG_ON(!len || len >= atomic_read(px_used(pd)));
212 
213 	do {
214 		struct i915_page_table *pt = pd->entry[idx];
215 
216 		if (atomic_fetch_inc(&pt->used) >> gen8_pd_shift(1) &&
217 		    gen8_pd_contains(start, end, lvl)) {
218 			DBG("%s(%p):{ lvl:%d, idx:%d, start:%llx, end:%llx } removing pd\n",
219 			    __func__, vm, lvl + 1, idx, start, end);
220 			clear_pd_entry(pd, idx, scratch);
221 			__gen8_ppgtt_cleanup(vm, as_pd(pt), I915_PDES, lvl);
222 			start += (u64)I915_PDES << gen8_pd_shift(lvl);
223 			continue;
224 		}
225 
226 		if (lvl) {
227 			start = __gen8_ppgtt_clear(vm, as_pd(pt),
228 						   start, end, lvl);
229 		} else {
230 			unsigned int count;
231 			u64 *vaddr;
232 
233 			count = gen8_pt_count(start, end);
234 			DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d } removing pte\n",
235 			    __func__, vm, lvl, start, end,
236 			    gen8_pd_index(start, 0), count,
237 			    atomic_read(&pt->used));
238 			GEM_BUG_ON(!count || count >= atomic_read(&pt->used));
239 
240 			vaddr = kmap_atomic_px(pt);
241 			memset64(vaddr + gen8_pd_index(start, 0),
242 				 vm->scratch[0]->encode,
243 				 count);
244 			kunmap_atomic(vaddr);
245 
246 			atomic_sub(count, &pt->used);
247 			start += count;
248 		}
249 
250 		if (release_pd_entry(pd, idx, pt, scratch))
251 			free_px(vm, pt, lvl);
252 	} while (idx++, --len);
253 
254 	return start;
255 }
256 
257 static void gen8_ppgtt_clear(struct i915_address_space *vm,
258 			     u64 start, u64 length)
259 {
260 	GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
261 	GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
262 	GEM_BUG_ON(range_overflows(start, length, vm->total));
263 
264 	start >>= GEN8_PTE_SHIFT;
265 	length >>= GEN8_PTE_SHIFT;
266 	GEM_BUG_ON(length == 0);
267 
268 	__gen8_ppgtt_clear(vm, i915_vm_to_ppgtt(vm)->pd,
269 			   start, start + length, vm->top);
270 }
271 
272 static void __gen8_ppgtt_alloc(struct i915_address_space * const vm,
273 			       struct i915_vm_pt_stash *stash,
274 			       struct i915_page_directory * const pd,
275 			       u64 * const start, const u64 end, int lvl)
276 {
277 	unsigned int idx, len;
278 
279 	GEM_BUG_ON(end > vm->total >> GEN8_PTE_SHIFT);
280 
281 	len = gen8_pd_range(*start, end, lvl--, &idx);
282 	DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d }\n",
283 	    __func__, vm, lvl + 1, *start, end,
284 	    idx, len, atomic_read(px_used(pd)));
285 	GEM_BUG_ON(!len || (idx + len - 1) >> gen8_pd_shift(1));
286 
287 	spin_lock(&pd->lock);
288 	GEM_BUG_ON(!atomic_read(px_used(pd))); /* Must be pinned! */
289 	do {
290 		struct i915_page_table *pt = pd->entry[idx];
291 
292 		if (!pt) {
293 			spin_unlock(&pd->lock);
294 
295 			DBG("%s(%p):{ lvl:%d, idx:%d } allocating new tree\n",
296 			    __func__, vm, lvl + 1, idx);
297 
298 			pt = stash->pt[!!lvl];
299 			__i915_gem_object_pin_pages(pt->base);
300 			i915_gem_object_make_unshrinkable(pt->base);
301 
302 			if (lvl ||
303 			    gen8_pt_count(*start, end) < I915_PDES ||
304 			    intel_vgpu_active(vm->i915))
305 				fill_px(pt, vm->scratch[lvl]->encode);
306 
307 			spin_lock(&pd->lock);
308 			if (likely(!pd->entry[idx])) {
309 				stash->pt[!!lvl] = pt->stash;
310 				atomic_set(&pt->used, 0);
311 				set_pd_entry(pd, idx, pt);
312 			} else {
313 				pt = pd->entry[idx];
314 			}
315 		}
316 
317 		if (lvl) {
318 			atomic_inc(&pt->used);
319 			spin_unlock(&pd->lock);
320 
321 			__gen8_ppgtt_alloc(vm, stash,
322 					   as_pd(pt), start, end, lvl);
323 
324 			spin_lock(&pd->lock);
325 			atomic_dec(&pt->used);
326 			GEM_BUG_ON(!atomic_read(&pt->used));
327 		} else {
328 			unsigned int count = gen8_pt_count(*start, end);
329 
330 			DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d } inserting pte\n",
331 			    __func__, vm, lvl, *start, end,
332 			    gen8_pd_index(*start, 0), count,
333 			    atomic_read(&pt->used));
334 
335 			atomic_add(count, &pt->used);
336 			/* All other pdes may be simultaneously removed */
337 			GEM_BUG_ON(atomic_read(&pt->used) > NALLOC * I915_PDES);
338 			*start += count;
339 		}
340 	} while (idx++, --len);
341 	spin_unlock(&pd->lock);
342 }
343 
344 static void gen8_ppgtt_alloc(struct i915_address_space *vm,
345 			     struct i915_vm_pt_stash *stash,
346 			     u64 start, u64 length)
347 {
348 	GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
349 	GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
350 	GEM_BUG_ON(range_overflows(start, length, vm->total));
351 
352 	start >>= GEN8_PTE_SHIFT;
353 	length >>= GEN8_PTE_SHIFT;
354 	GEM_BUG_ON(length == 0);
355 
356 	__gen8_ppgtt_alloc(vm, stash, i915_vm_to_ppgtt(vm)->pd,
357 			   &start, start + length, vm->top);
358 }
359 
360 static __always_inline u64
361 gen8_ppgtt_insert_pte(struct i915_ppgtt *ppgtt,
362 		      struct i915_page_directory *pdp,
363 		      struct sgt_dma *iter,
364 		      u64 idx,
365 		      enum i915_cache_level cache_level,
366 		      u32 flags)
367 {
368 	struct i915_page_directory *pd;
369 	const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
370 	gen8_pte_t *vaddr;
371 
372 	pd = i915_pd_entry(pdp, gen8_pd_index(idx, 2));
373 	vaddr = kmap_atomic_px(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
374 	do {
375 		GEM_BUG_ON(iter->sg->length < I915_GTT_PAGE_SIZE);
376 		vaddr[gen8_pd_index(idx, 0)] = pte_encode | iter->dma;
377 
378 		iter->dma += I915_GTT_PAGE_SIZE;
379 		if (iter->dma >= iter->max) {
380 			iter->sg = __sg_next(iter->sg);
381 			if (!iter->sg) {
382 				idx = 0;
383 				break;
384 			}
385 
386 			iter->dma = sg_dma_address(iter->sg);
387 			iter->max = iter->dma + iter->sg->length;
388 		}
389 
390 		if (gen8_pd_index(++idx, 0) == 0) {
391 			if (gen8_pd_index(idx, 1) == 0) {
392 				/* Limited by sg length for 3lvl */
393 				if (gen8_pd_index(idx, 2) == 0)
394 					break;
395 
396 				pd = pdp->entry[gen8_pd_index(idx, 2)];
397 			}
398 
399 			clflush_cache_range(vaddr, PAGE_SIZE);
400 			kunmap_atomic(vaddr);
401 			vaddr = kmap_atomic_px(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
402 		}
403 	} while (1);
404 	clflush_cache_range(vaddr, PAGE_SIZE);
405 	kunmap_atomic(vaddr);
406 
407 	return idx;
408 }
409 
410 static void gen8_ppgtt_insert_huge(struct i915_vma *vma,
411 				   struct sgt_dma *iter,
412 				   enum i915_cache_level cache_level,
413 				   u32 flags)
414 {
415 	const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
416 	u64 start = vma->node.start;
417 	dma_addr_t rem = iter->sg->length;
418 
419 	GEM_BUG_ON(!i915_vm_is_4lvl(vma->vm));
420 
421 	do {
422 		struct i915_page_directory * const pdp =
423 			gen8_pdp_for_page_address(vma->vm, start);
424 		struct i915_page_directory * const pd =
425 			i915_pd_entry(pdp, __gen8_pte_index(start, 2));
426 		gen8_pte_t encode = pte_encode;
427 		unsigned int maybe_64K = -1;
428 		unsigned int page_size;
429 		gen8_pte_t *vaddr;
430 		u16 index;
431 
432 		if (vma->page_sizes.sg & I915_GTT_PAGE_SIZE_2M &&
433 		    IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_2M) &&
434 		    rem >= I915_GTT_PAGE_SIZE_2M &&
435 		    !__gen8_pte_index(start, 0)) {
436 			index = __gen8_pte_index(start, 1);
437 			encode |= GEN8_PDE_PS_2M;
438 			page_size = I915_GTT_PAGE_SIZE_2M;
439 
440 			vaddr = kmap_atomic_px(pd);
441 		} else {
442 			struct i915_page_table *pt =
443 				i915_pt_entry(pd, __gen8_pte_index(start, 1));
444 
445 			index = __gen8_pte_index(start, 0);
446 			page_size = I915_GTT_PAGE_SIZE;
447 
448 			if (!index &&
449 			    vma->page_sizes.sg & I915_GTT_PAGE_SIZE_64K &&
450 			    IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_64K) &&
451 			    (IS_ALIGNED(rem, I915_GTT_PAGE_SIZE_64K) ||
452 			     rem >= (I915_PDES - index) * I915_GTT_PAGE_SIZE))
453 				maybe_64K = __gen8_pte_index(start, 1);
454 
455 			vaddr = kmap_atomic_px(pt);
456 		}
457 
458 		do {
459 			GEM_BUG_ON(iter->sg->length < page_size);
460 			vaddr[index++] = encode | iter->dma;
461 
462 			start += page_size;
463 			iter->dma += page_size;
464 			rem -= page_size;
465 			if (iter->dma >= iter->max) {
466 				iter->sg = __sg_next(iter->sg);
467 				if (!iter->sg)
468 					break;
469 
470 				rem = iter->sg->length;
471 				iter->dma = sg_dma_address(iter->sg);
472 				iter->max = iter->dma + rem;
473 
474 				if (maybe_64K != -1 && index < I915_PDES &&
475 				    !(IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_64K) &&
476 				      (IS_ALIGNED(rem, I915_GTT_PAGE_SIZE_64K) ||
477 				       rem >= (I915_PDES - index) * I915_GTT_PAGE_SIZE)))
478 					maybe_64K = -1;
479 
480 				if (unlikely(!IS_ALIGNED(iter->dma, page_size)))
481 					break;
482 			}
483 		} while (rem >= page_size && index < I915_PDES);
484 
485 		clflush_cache_range(vaddr, PAGE_SIZE);
486 		kunmap_atomic(vaddr);
487 
488 		/*
489 		 * Is it safe to mark the 2M block as 64K? -- Either we have
490 		 * filled whole page-table with 64K entries, or filled part of
491 		 * it and have reached the end of the sg table and we have
492 		 * enough padding.
493 		 */
494 		if (maybe_64K != -1 &&
495 		    (index == I915_PDES ||
496 		     (i915_vm_has_scratch_64K(vma->vm) &&
497 		      !iter->sg && IS_ALIGNED(vma->node.start +
498 					      vma->node.size,
499 					      I915_GTT_PAGE_SIZE_2M)))) {
500 			vaddr = kmap_atomic_px(pd);
501 			vaddr[maybe_64K] |= GEN8_PDE_IPS_64K;
502 			kunmap_atomic(vaddr);
503 			page_size = I915_GTT_PAGE_SIZE_64K;
504 
505 			/*
506 			 * We write all 4K page entries, even when using 64K
507 			 * pages. In order to verify that the HW isn't cheating
508 			 * by using the 4K PTE instead of the 64K PTE, we want
509 			 * to remove all the surplus entries. If the HW skipped
510 			 * the 64K PTE, it will read/write into the scratch page
511 			 * instead - which we detect as missing results during
512 			 * selftests.
513 			 */
514 			if (I915_SELFTEST_ONLY(vma->vm->scrub_64K)) {
515 				u16 i;
516 
517 				encode = vma->vm->scratch[0]->encode;
518 				vaddr = kmap_atomic_px(i915_pt_entry(pd, maybe_64K));
519 
520 				for (i = 1; i < index; i += 16)
521 					memset64(vaddr + i, encode, 15);
522 
523 				kunmap_atomic(vaddr);
524 			}
525 		}
526 
527 		vma->page_sizes.gtt |= page_size;
528 	} while (iter->sg);
529 }
530 
531 static void gen8_ppgtt_insert(struct i915_address_space *vm,
532 			      struct i915_vma *vma,
533 			      enum i915_cache_level cache_level,
534 			      u32 flags)
535 {
536 	struct i915_ppgtt * const ppgtt = i915_vm_to_ppgtt(vm);
537 	struct sgt_dma iter = sgt_dma(vma);
538 
539 	if (vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
540 		gen8_ppgtt_insert_huge(vma, &iter, cache_level, flags);
541 	} else  {
542 		u64 idx = vma->node.start >> GEN8_PTE_SHIFT;
543 
544 		do {
545 			struct i915_page_directory * const pdp =
546 				gen8_pdp_for_page_index(vm, idx);
547 
548 			idx = gen8_ppgtt_insert_pte(ppgtt, pdp, &iter, idx,
549 						    cache_level, flags);
550 		} while (idx);
551 
552 		vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
553 	}
554 }
555 
556 static int gen8_init_scratch(struct i915_address_space *vm)
557 {
558 	int ret;
559 	int i;
560 
561 	/*
562 	 * If everybody agrees to not to write into the scratch page,
563 	 * we can reuse it for all vm, keeping contexts and processes separate.
564 	 */
565 	if (vm->has_read_only && vm->gt->vm && !i915_is_ggtt(vm->gt->vm)) {
566 		struct i915_address_space *clone = vm->gt->vm;
567 
568 		GEM_BUG_ON(!clone->has_read_only);
569 
570 		vm->scratch_order = clone->scratch_order;
571 		for (i = 0; i <= vm->top; i++)
572 			vm->scratch[i] = i915_gem_object_get(clone->scratch[i]);
573 
574 		return 0;
575 	}
576 
577 	ret = setup_scratch_page(vm);
578 	if (ret)
579 		return ret;
580 
581 	vm->scratch[0]->encode =
582 		gen8_pte_encode(px_dma(vm->scratch[0]),
583 				I915_CACHE_LLC, vm->has_read_only);
584 
585 	for (i = 1; i <= vm->top; i++) {
586 		struct drm_i915_gem_object *obj;
587 
588 		obj = vm->alloc_pt_dma(vm, I915_GTT_PAGE_SIZE_4K);
589 		if (IS_ERR(obj))
590 			goto free_scratch;
591 
592 		ret = pin_pt_dma(vm, obj);
593 		if (ret) {
594 			i915_gem_object_put(obj);
595 			goto free_scratch;
596 		}
597 
598 		fill_px(obj, vm->scratch[i - 1]->encode);
599 		obj->encode = gen8_pde_encode(px_dma(obj), I915_CACHE_LLC);
600 
601 		vm->scratch[i] = obj;
602 	}
603 
604 	return 0;
605 
606 free_scratch:
607 	while (i--)
608 		i915_gem_object_put(vm->scratch[i]);
609 	return -ENOMEM;
610 }
611 
612 static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
613 {
614 	struct i915_address_space *vm = &ppgtt->vm;
615 	struct i915_page_directory *pd = ppgtt->pd;
616 	unsigned int idx;
617 
618 	GEM_BUG_ON(vm->top != 2);
619 	GEM_BUG_ON(gen8_pd_top_count(vm) != GEN8_3LVL_PDPES);
620 
621 	for (idx = 0; idx < GEN8_3LVL_PDPES; idx++) {
622 		struct i915_page_directory *pde;
623 		int err;
624 
625 		pde = alloc_pd(vm);
626 		if (IS_ERR(pde))
627 			return PTR_ERR(pde);
628 
629 		err = pin_pt_dma(vm, pde->pt.base);
630 		if (err) {
631 			i915_gem_object_put(pde->pt.base);
632 			free_pd(vm, pde);
633 			return err;
634 		}
635 
636 		fill_px(pde, vm->scratch[1]->encode);
637 		set_pd_entry(pd, idx, pde);
638 		atomic_inc(px_used(pde)); /* keep pinned */
639 	}
640 	wmb();
641 
642 	return 0;
643 }
644 
645 static struct i915_page_directory *
646 gen8_alloc_top_pd(struct i915_address_space *vm)
647 {
648 	const unsigned int count = gen8_pd_top_count(vm);
649 	struct i915_page_directory *pd;
650 	int err;
651 
652 	GEM_BUG_ON(count > I915_PDES);
653 
654 	pd = __alloc_pd(count);
655 	if (unlikely(!pd))
656 		return ERR_PTR(-ENOMEM);
657 
658 	pd->pt.base = vm->alloc_pt_dma(vm, I915_GTT_PAGE_SIZE_4K);
659 	if (IS_ERR(pd->pt.base)) {
660 		err = PTR_ERR(pd->pt.base);
661 		pd->pt.base = NULL;
662 		goto err_pd;
663 	}
664 
665 	err = pin_pt_dma(vm, pd->pt.base);
666 	if (err)
667 		goto err_pd;
668 
669 	fill_page_dma(px_base(pd), vm->scratch[vm->top]->encode, count);
670 	atomic_inc(px_used(pd)); /* mark as pinned */
671 	return pd;
672 
673 err_pd:
674 	free_pd(vm, pd);
675 	return ERR_PTR(err);
676 }
677 
678 /*
679  * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
680  * with a net effect resembling a 2-level page table in normal x86 terms. Each
681  * PDP represents 1GB of memory 4 * 512 * 512 * 4096 = 4GB legacy 32b address
682  * space.
683  *
684  */
685 struct i915_ppgtt *gen8_ppgtt_create(struct intel_gt *gt)
686 {
687 	struct i915_ppgtt *ppgtt;
688 	int err;
689 
690 	ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
691 	if (!ppgtt)
692 		return ERR_PTR(-ENOMEM);
693 
694 	ppgtt_init(ppgtt, gt);
695 	ppgtt->vm.top = i915_vm_is_4lvl(&ppgtt->vm) ? 3 : 2;
696 	ppgtt->vm.pd_shift = ilog2(SZ_4K * SZ_4K / sizeof(gen8_pte_t));
697 
698 	/*
699 	 * From bdw, there is hw support for read-only pages in the PPGTT.
700 	 *
701 	 * Gen11 has HSDES#:1807136187 unresolved. Disable ro support
702 	 * for now.
703 	 *
704 	 * Gen12 has inherited the same read-only fault issue from gen11.
705 	 */
706 	ppgtt->vm.has_read_only = !IS_GEN_RANGE(gt->i915, 11, 12);
707 
708 	ppgtt->vm.alloc_pt_dma = alloc_pt_dma;
709 
710 	err = gen8_init_scratch(&ppgtt->vm);
711 	if (err)
712 		goto err_free;
713 
714 	ppgtt->pd = gen8_alloc_top_pd(&ppgtt->vm);
715 	if (IS_ERR(ppgtt->pd)) {
716 		err = PTR_ERR(ppgtt->pd);
717 		goto err_free_scratch;
718 	}
719 
720 	if (!i915_vm_is_4lvl(&ppgtt->vm)) {
721 		err = gen8_preallocate_top_level_pdp(ppgtt);
722 		if (err)
723 			goto err_free_pd;
724 	}
725 
726 	ppgtt->vm.bind_async_flags = I915_VMA_LOCAL_BIND;
727 	ppgtt->vm.insert_entries = gen8_ppgtt_insert;
728 	ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc;
729 	ppgtt->vm.clear_range = gen8_ppgtt_clear;
730 
731 	ppgtt->vm.pte_encode = gen8_pte_encode;
732 
733 	if (intel_vgpu_active(gt->i915))
734 		gen8_ppgtt_notify_vgt(ppgtt, true);
735 
736 	ppgtt->vm.cleanup = gen8_ppgtt_cleanup;
737 
738 	return ppgtt;
739 
740 err_free_pd:
741 	__gen8_ppgtt_cleanup(&ppgtt->vm, ppgtt->pd,
742 			     gen8_pd_top_count(&ppgtt->vm), ppgtt->vm.top);
743 err_free_scratch:
744 	free_scratch(&ppgtt->vm);
745 err_free:
746 	kfree(ppgtt);
747 	return ERR_PTR(err);
748 }
749