xref: /openbmc/linux/drivers/gpu/drm/i915/gt/gen8_ppgtt.c (revision dc6a81c3)
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_vgpu.h"
12 #include "intel_gt.h"
13 #include "intel_gtt.h"
14 
15 static u64 gen8_pde_encode(const dma_addr_t addr,
16 			   const enum i915_cache_level level)
17 {
18 	u64 pde = addr | _PAGE_PRESENT | _PAGE_RW;
19 
20 	if (level != I915_CACHE_NONE)
21 		pde |= PPAT_CACHED_PDE;
22 	else
23 		pde |= PPAT_UNCACHED;
24 
25 	return pde;
26 }
27 
28 static void gen8_ppgtt_notify_vgt(struct i915_ppgtt *ppgtt, bool create)
29 {
30 	struct drm_i915_private *i915 = ppgtt->vm.i915;
31 	struct intel_uncore *uncore = ppgtt->vm.gt->uncore;
32 	enum vgt_g2v_type msg;
33 	int i;
34 
35 	if (create)
36 		atomic_inc(px_used(ppgtt->pd)); /* never remove */
37 	else
38 		atomic_dec(px_used(ppgtt->pd));
39 
40 	mutex_lock(&i915->vgpu.lock);
41 
42 	if (i915_vm_is_4lvl(&ppgtt->vm)) {
43 		const u64 daddr = px_dma(ppgtt->pd);
44 
45 		intel_uncore_write(uncore,
46 				   vgtif_reg(pdp[0].lo), lower_32_bits(daddr));
47 		intel_uncore_write(uncore,
48 				   vgtif_reg(pdp[0].hi), upper_32_bits(daddr));
49 
50 		msg = create ?
51 			VGT_G2V_PPGTT_L4_PAGE_TABLE_CREATE :
52 			VGT_G2V_PPGTT_L4_PAGE_TABLE_DESTROY;
53 	} else {
54 		for (i = 0; i < GEN8_3LVL_PDPES; i++) {
55 			const u64 daddr = i915_page_dir_dma_addr(ppgtt, i);
56 
57 			intel_uncore_write(uncore,
58 					   vgtif_reg(pdp[i].lo),
59 					   lower_32_bits(daddr));
60 			intel_uncore_write(uncore,
61 					   vgtif_reg(pdp[i].hi),
62 					   upper_32_bits(daddr));
63 		}
64 
65 		msg = create ?
66 			VGT_G2V_PPGTT_L3_PAGE_TABLE_CREATE :
67 			VGT_G2V_PPGTT_L3_PAGE_TABLE_DESTROY;
68 	}
69 
70 	/* g2v_notify atomically (via hv trap) consumes the message packet. */
71 	intel_uncore_write(uncore, vgtif_reg(g2v_notify), msg);
72 
73 	mutex_unlock(&i915->vgpu.lock);
74 }
75 
76 /* Index shifts into the pagetable are offset by GEN8_PTE_SHIFT [12] */
77 #define GEN8_PAGE_SIZE (SZ_4K) /* page and page-directory sizes are the same */
78 #define GEN8_PTE_SHIFT (ilog2(GEN8_PAGE_SIZE))
79 #define GEN8_PDES (GEN8_PAGE_SIZE / sizeof(u64))
80 #define gen8_pd_shift(lvl) ((lvl) * ilog2(GEN8_PDES))
81 #define gen8_pd_index(i, lvl) i915_pde_index((i), gen8_pd_shift(lvl))
82 #define __gen8_pte_shift(lvl) (GEN8_PTE_SHIFT + gen8_pd_shift(lvl))
83 #define __gen8_pte_index(a, lvl) i915_pde_index((a), __gen8_pte_shift(lvl))
84 
85 #define as_pd(x) container_of((x), typeof(struct i915_page_directory), pt)
86 
87 static inline unsigned int
88 gen8_pd_range(u64 start, u64 end, int lvl, unsigned int *idx)
89 {
90 	const int shift = gen8_pd_shift(lvl);
91 	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
92 
93 	GEM_BUG_ON(start >= end);
94 	end += ~mask >> gen8_pd_shift(1);
95 
96 	*idx = i915_pde_index(start, shift);
97 	if ((start ^ end) & mask)
98 		return GEN8_PDES - *idx;
99 	else
100 		return i915_pde_index(end, shift) - *idx;
101 }
102 
103 static inline bool gen8_pd_contains(u64 start, u64 end, int lvl)
104 {
105 	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
106 
107 	GEM_BUG_ON(start >= end);
108 	return (start ^ end) & mask && (start & ~mask) == 0;
109 }
110 
111 static inline unsigned int gen8_pt_count(u64 start, u64 end)
112 {
113 	GEM_BUG_ON(start >= end);
114 	if ((start ^ end) >> gen8_pd_shift(1))
115 		return GEN8_PDES - (start & (GEN8_PDES - 1));
116 	else
117 		return end - start;
118 }
119 
120 static inline unsigned int
121 gen8_pd_top_count(const struct i915_address_space *vm)
122 {
123 	unsigned int shift = __gen8_pte_shift(vm->top);
124 	return (vm->total + (1ull << shift) - 1) >> shift;
125 }
126 
127 static inline struct i915_page_directory *
128 gen8_pdp_for_page_index(struct i915_address_space * const vm, const u64 idx)
129 {
130 	struct i915_ppgtt * const ppgtt = i915_vm_to_ppgtt(vm);
131 
132 	if (vm->top == 2)
133 		return ppgtt->pd;
134 	else
135 		return i915_pd_entry(ppgtt->pd, gen8_pd_index(idx, vm->top));
136 }
137 
138 static inline struct i915_page_directory *
139 gen8_pdp_for_page_address(struct i915_address_space * const vm, const u64 addr)
140 {
141 	return gen8_pdp_for_page_index(vm, addr >> GEN8_PTE_SHIFT);
142 }
143 
144 static void __gen8_ppgtt_cleanup(struct i915_address_space *vm,
145 				 struct i915_page_directory *pd,
146 				 int count, int lvl)
147 {
148 	if (lvl) {
149 		void **pde = pd->entry;
150 
151 		do {
152 			if (!*pde)
153 				continue;
154 
155 			__gen8_ppgtt_cleanup(vm, *pde, GEN8_PDES, lvl - 1);
156 		} while (pde++, --count);
157 	}
158 
159 	free_px(vm, pd);
160 }
161 
162 static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
163 {
164 	struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
165 
166 	if (intel_vgpu_active(vm->i915))
167 		gen8_ppgtt_notify_vgt(ppgtt, false);
168 
169 	__gen8_ppgtt_cleanup(vm, ppgtt->pd, gen8_pd_top_count(vm), vm->top);
170 	free_scratch(vm);
171 }
172 
173 static u64 __gen8_ppgtt_clear(struct i915_address_space * const vm,
174 			      struct i915_page_directory * const pd,
175 			      u64 start, const u64 end, int lvl)
176 {
177 	const struct i915_page_scratch * const scratch = &vm->scratch[lvl];
178 	unsigned int idx, len;
179 
180 	GEM_BUG_ON(end > vm->total >> GEN8_PTE_SHIFT);
181 
182 	len = gen8_pd_range(start, end, lvl--, &idx);
183 	DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d }\n",
184 	    __func__, vm, lvl + 1, start, end,
185 	    idx, len, atomic_read(px_used(pd)));
186 	GEM_BUG_ON(!len || len >= atomic_read(px_used(pd)));
187 
188 	do {
189 		struct i915_page_table *pt = pd->entry[idx];
190 
191 		if (atomic_fetch_inc(&pt->used) >> gen8_pd_shift(1) &&
192 		    gen8_pd_contains(start, end, lvl)) {
193 			DBG("%s(%p):{ lvl:%d, idx:%d, start:%llx, end:%llx } removing pd\n",
194 			    __func__, vm, lvl + 1, idx, start, end);
195 			clear_pd_entry(pd, idx, scratch);
196 			__gen8_ppgtt_cleanup(vm, as_pd(pt), I915_PDES, lvl);
197 			start += (u64)I915_PDES << gen8_pd_shift(lvl);
198 			continue;
199 		}
200 
201 		if (lvl) {
202 			start = __gen8_ppgtt_clear(vm, as_pd(pt),
203 						   start, end, lvl);
204 		} else {
205 			unsigned int count;
206 			u64 *vaddr;
207 
208 			count = gen8_pt_count(start, end);
209 			DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d } removing pte\n",
210 			    __func__, vm, lvl, start, end,
211 			    gen8_pd_index(start, 0), count,
212 			    atomic_read(&pt->used));
213 			GEM_BUG_ON(!count || count >= atomic_read(&pt->used));
214 
215 			vaddr = kmap_atomic_px(pt);
216 			memset64(vaddr + gen8_pd_index(start, 0),
217 				 vm->scratch[0].encode,
218 				 count);
219 			kunmap_atomic(vaddr);
220 
221 			atomic_sub(count, &pt->used);
222 			start += count;
223 		}
224 
225 		if (release_pd_entry(pd, idx, pt, scratch))
226 			free_px(vm, pt);
227 	} while (idx++, --len);
228 
229 	return start;
230 }
231 
232 static void gen8_ppgtt_clear(struct i915_address_space *vm,
233 			     u64 start, u64 length)
234 {
235 	GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
236 	GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
237 	GEM_BUG_ON(range_overflows(start, length, vm->total));
238 
239 	start >>= GEN8_PTE_SHIFT;
240 	length >>= GEN8_PTE_SHIFT;
241 	GEM_BUG_ON(length == 0);
242 
243 	__gen8_ppgtt_clear(vm, i915_vm_to_ppgtt(vm)->pd,
244 			   start, start + length, vm->top);
245 }
246 
247 static int __gen8_ppgtt_alloc(struct i915_address_space * const vm,
248 			      struct i915_page_directory * const pd,
249 			      u64 * const start, const u64 end, int lvl)
250 {
251 	const struct i915_page_scratch * const scratch = &vm->scratch[lvl];
252 	struct i915_page_table *alloc = NULL;
253 	unsigned int idx, len;
254 	int ret = 0;
255 
256 	GEM_BUG_ON(end > vm->total >> GEN8_PTE_SHIFT);
257 
258 	len = gen8_pd_range(*start, end, lvl--, &idx);
259 	DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d }\n",
260 	    __func__, vm, lvl + 1, *start, end,
261 	    idx, len, atomic_read(px_used(pd)));
262 	GEM_BUG_ON(!len || (idx + len - 1) >> gen8_pd_shift(1));
263 
264 	spin_lock(&pd->lock);
265 	GEM_BUG_ON(!atomic_read(px_used(pd))); /* Must be pinned! */
266 	do {
267 		struct i915_page_table *pt = pd->entry[idx];
268 
269 		if (!pt) {
270 			spin_unlock(&pd->lock);
271 
272 			DBG("%s(%p):{ lvl:%d, idx:%d } allocating new tree\n",
273 			    __func__, vm, lvl + 1, idx);
274 
275 			pt = fetch_and_zero(&alloc);
276 			if (lvl) {
277 				if (!pt) {
278 					pt = &alloc_pd(vm)->pt;
279 					if (IS_ERR(pt)) {
280 						ret = PTR_ERR(pt);
281 						goto out;
282 					}
283 				}
284 
285 				fill_px(pt, vm->scratch[lvl].encode);
286 			} else {
287 				if (!pt) {
288 					pt = alloc_pt(vm);
289 					if (IS_ERR(pt)) {
290 						ret = PTR_ERR(pt);
291 						goto out;
292 					}
293 				}
294 
295 				if (intel_vgpu_active(vm->i915) ||
296 				    gen8_pt_count(*start, end) < I915_PDES)
297 					fill_px(pt, vm->scratch[lvl].encode);
298 			}
299 
300 			spin_lock(&pd->lock);
301 			if (likely(!pd->entry[idx]))
302 				set_pd_entry(pd, idx, pt);
303 			else
304 				alloc = pt, pt = pd->entry[idx];
305 		}
306 
307 		if (lvl) {
308 			atomic_inc(&pt->used);
309 			spin_unlock(&pd->lock);
310 
311 			ret = __gen8_ppgtt_alloc(vm, as_pd(pt),
312 						 start, end, lvl);
313 			if (unlikely(ret)) {
314 				if (release_pd_entry(pd, idx, pt, scratch))
315 					free_px(vm, pt);
316 				goto out;
317 			}
318 
319 			spin_lock(&pd->lock);
320 			atomic_dec(&pt->used);
321 			GEM_BUG_ON(!atomic_read(&pt->used));
322 		} else {
323 			unsigned int count = gen8_pt_count(*start, end);
324 
325 			DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d } inserting pte\n",
326 			    __func__, vm, lvl, *start, end,
327 			    gen8_pd_index(*start, 0), count,
328 			    atomic_read(&pt->used));
329 
330 			atomic_add(count, &pt->used);
331 			/* All other pdes may be simultaneously removed */
332 			GEM_BUG_ON(atomic_read(&pt->used) > NALLOC * I915_PDES);
333 			*start += count;
334 		}
335 	} while (idx++, --len);
336 	spin_unlock(&pd->lock);
337 out:
338 	if (alloc)
339 		free_px(vm, alloc);
340 	return ret;
341 }
342 
343 static int gen8_ppgtt_alloc(struct i915_address_space *vm,
344 			    u64 start, u64 length)
345 {
346 	u64 from;
347 	int err;
348 
349 	GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
350 	GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
351 	GEM_BUG_ON(range_overflows(start, length, vm->total));
352 
353 	start >>= GEN8_PTE_SHIFT;
354 	length >>= GEN8_PTE_SHIFT;
355 	GEM_BUG_ON(length == 0);
356 	from = start;
357 
358 	err = __gen8_ppgtt_alloc(vm, i915_vm_to_ppgtt(vm)->pd,
359 				 &start, start + length, vm->top);
360 	if (unlikely(err && from != start))
361 		__gen8_ppgtt_clear(vm, i915_vm_to_ppgtt(vm)->pd,
362 				   from, start, vm->top);
363 
364 	return err;
365 }
366 
367 static __always_inline u64
368 gen8_ppgtt_insert_pte(struct i915_ppgtt *ppgtt,
369 		      struct i915_page_directory *pdp,
370 		      struct sgt_dma *iter,
371 		      u64 idx,
372 		      enum i915_cache_level cache_level,
373 		      u32 flags)
374 {
375 	struct i915_page_directory *pd;
376 	const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
377 	gen8_pte_t *vaddr;
378 
379 	pd = i915_pd_entry(pdp, gen8_pd_index(idx, 2));
380 	vaddr = kmap_atomic_px(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
381 	do {
382 		GEM_BUG_ON(iter->sg->length < I915_GTT_PAGE_SIZE);
383 		vaddr[gen8_pd_index(idx, 0)] = pte_encode | iter->dma;
384 
385 		iter->dma += I915_GTT_PAGE_SIZE;
386 		if (iter->dma >= iter->max) {
387 			iter->sg = __sg_next(iter->sg);
388 			if (!iter->sg) {
389 				idx = 0;
390 				break;
391 			}
392 
393 			iter->dma = sg_dma_address(iter->sg);
394 			iter->max = iter->dma + iter->sg->length;
395 		}
396 
397 		if (gen8_pd_index(++idx, 0) == 0) {
398 			if (gen8_pd_index(idx, 1) == 0) {
399 				/* Limited by sg length for 3lvl */
400 				if (gen8_pd_index(idx, 2) == 0)
401 					break;
402 
403 				pd = pdp->entry[gen8_pd_index(idx, 2)];
404 			}
405 
406 			kunmap_atomic(vaddr);
407 			vaddr = kmap_atomic_px(i915_pt_entry(pd, gen8_pd_index(idx, 1)));
408 		}
409 	} while (1);
410 	kunmap_atomic(vaddr);
411 
412 	return idx;
413 }
414 
415 static void gen8_ppgtt_insert_huge(struct i915_vma *vma,
416 				   struct sgt_dma *iter,
417 				   enum i915_cache_level cache_level,
418 				   u32 flags)
419 {
420 	const gen8_pte_t pte_encode = gen8_pte_encode(0, cache_level, flags);
421 	u64 start = vma->node.start;
422 	dma_addr_t rem = iter->sg->length;
423 
424 	GEM_BUG_ON(!i915_vm_is_4lvl(vma->vm));
425 
426 	do {
427 		struct i915_page_directory * const pdp =
428 			gen8_pdp_for_page_address(vma->vm, start);
429 		struct i915_page_directory * const pd =
430 			i915_pd_entry(pdp, __gen8_pte_index(start, 2));
431 		gen8_pte_t encode = pte_encode;
432 		unsigned int maybe_64K = -1;
433 		unsigned int page_size;
434 		gen8_pte_t *vaddr;
435 		u16 index;
436 
437 		if (vma->page_sizes.sg & I915_GTT_PAGE_SIZE_2M &&
438 		    IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_2M) &&
439 		    rem >= I915_GTT_PAGE_SIZE_2M &&
440 		    !__gen8_pte_index(start, 0)) {
441 			index = __gen8_pte_index(start, 1);
442 			encode |= GEN8_PDE_PS_2M;
443 			page_size = I915_GTT_PAGE_SIZE_2M;
444 
445 			vaddr = kmap_atomic_px(pd);
446 		} else {
447 			struct i915_page_table *pt =
448 				i915_pt_entry(pd, __gen8_pte_index(start, 1));
449 
450 			index = __gen8_pte_index(start, 0);
451 			page_size = I915_GTT_PAGE_SIZE;
452 
453 			if (!index &&
454 			    vma->page_sizes.sg & I915_GTT_PAGE_SIZE_64K &&
455 			    IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_64K) &&
456 			    (IS_ALIGNED(rem, I915_GTT_PAGE_SIZE_64K) ||
457 			     rem >= (I915_PDES - index) * I915_GTT_PAGE_SIZE))
458 				maybe_64K = __gen8_pte_index(start, 1);
459 
460 			vaddr = kmap_atomic_px(pt);
461 		}
462 
463 		do {
464 			GEM_BUG_ON(iter->sg->length < page_size);
465 			vaddr[index++] = encode | iter->dma;
466 
467 			start += page_size;
468 			iter->dma += page_size;
469 			rem -= page_size;
470 			if (iter->dma >= iter->max) {
471 				iter->sg = __sg_next(iter->sg);
472 				if (!iter->sg)
473 					break;
474 
475 				rem = iter->sg->length;
476 				iter->dma = sg_dma_address(iter->sg);
477 				iter->max = iter->dma + rem;
478 
479 				if (maybe_64K != -1 && index < I915_PDES &&
480 				    !(IS_ALIGNED(iter->dma, I915_GTT_PAGE_SIZE_64K) &&
481 				      (IS_ALIGNED(rem, I915_GTT_PAGE_SIZE_64K) ||
482 				       rem >= (I915_PDES - index) * I915_GTT_PAGE_SIZE)))
483 					maybe_64K = -1;
484 
485 				if (unlikely(!IS_ALIGNED(iter->dma, page_size)))
486 					break;
487 			}
488 		} while (rem >= page_size && index < I915_PDES);
489 
490 		kunmap_atomic(vaddr);
491 
492 		/*
493 		 * Is it safe to mark the 2M block as 64K? -- Either we have
494 		 * filled whole page-table with 64K entries, or filled part of
495 		 * it and have reached the end of the sg table and we have
496 		 * enough padding.
497 		 */
498 		if (maybe_64K != -1 &&
499 		    (index == I915_PDES ||
500 		     (i915_vm_has_scratch_64K(vma->vm) &&
501 		      !iter->sg && IS_ALIGNED(vma->node.start +
502 					      vma->node.size,
503 					      I915_GTT_PAGE_SIZE_2M)))) {
504 			vaddr = kmap_atomic_px(pd);
505 			vaddr[maybe_64K] |= GEN8_PDE_IPS_64K;
506 			kunmap_atomic(vaddr);
507 			page_size = I915_GTT_PAGE_SIZE_64K;
508 
509 			/*
510 			 * We write all 4K page entries, even when using 64K
511 			 * pages. In order to verify that the HW isn't cheating
512 			 * by using the 4K PTE instead of the 64K PTE, we want
513 			 * to remove all the surplus entries. If the HW skipped
514 			 * the 64K PTE, it will read/write into the scratch page
515 			 * instead - which we detect as missing results during
516 			 * selftests.
517 			 */
518 			if (I915_SELFTEST_ONLY(vma->vm->scrub_64K)) {
519 				u16 i;
520 
521 				encode = vma->vm->scratch[0].encode;
522 				vaddr = kmap_atomic_px(i915_pt_entry(pd, maybe_64K));
523 
524 				for (i = 1; i < index; i += 16)
525 					memset64(vaddr + i, encode, 15);
526 
527 				kunmap_atomic(vaddr);
528 			}
529 		}
530 
531 		vma->page_sizes.gtt |= page_size;
532 	} while (iter->sg);
533 }
534 
535 static void gen8_ppgtt_insert(struct i915_address_space *vm,
536 			      struct i915_vma *vma,
537 			      enum i915_cache_level cache_level,
538 			      u32 flags)
539 {
540 	struct i915_ppgtt * const ppgtt = i915_vm_to_ppgtt(vm);
541 	struct sgt_dma iter = sgt_dma(vma);
542 
543 	if (vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
544 		gen8_ppgtt_insert_huge(vma, &iter, cache_level, flags);
545 	} else  {
546 		u64 idx = vma->node.start >> GEN8_PTE_SHIFT;
547 
548 		do {
549 			struct i915_page_directory * const pdp =
550 				gen8_pdp_for_page_index(vm, idx);
551 
552 			idx = gen8_ppgtt_insert_pte(ppgtt, pdp, &iter, idx,
553 						    cache_level, flags);
554 		} while (idx);
555 
556 		vma->page_sizes.gtt = I915_GTT_PAGE_SIZE;
557 	}
558 }
559 
560 static int gen8_init_scratch(struct i915_address_space *vm)
561 {
562 	int ret;
563 	int i;
564 
565 	/*
566 	 * If everybody agrees to not to write into the scratch page,
567 	 * we can reuse it for all vm, keeping contexts and processes separate.
568 	 */
569 	if (vm->has_read_only && vm->gt->vm && !i915_is_ggtt(vm->gt->vm)) {
570 		struct i915_address_space *clone = vm->gt->vm;
571 
572 		GEM_BUG_ON(!clone->has_read_only);
573 
574 		vm->scratch_order = clone->scratch_order;
575 		memcpy(vm->scratch, clone->scratch, sizeof(vm->scratch));
576 		px_dma(&vm->scratch[0]) = 0; /* no xfer of ownership */
577 		return 0;
578 	}
579 
580 	ret = setup_scratch_page(vm, __GFP_HIGHMEM);
581 	if (ret)
582 		return ret;
583 
584 	vm->scratch[0].encode =
585 		gen8_pte_encode(px_dma(&vm->scratch[0]),
586 				I915_CACHE_LLC, vm->has_read_only);
587 
588 	for (i = 1; i <= vm->top; i++) {
589 		if (unlikely(setup_page_dma(vm, px_base(&vm->scratch[i]))))
590 			goto free_scratch;
591 
592 		fill_px(&vm->scratch[i], vm->scratch[i - 1].encode);
593 		vm->scratch[i].encode =
594 			gen8_pde_encode(px_dma(&vm->scratch[i]),
595 					I915_CACHE_LLC);
596 	}
597 
598 	return 0;
599 
600 free_scratch:
601 	free_scratch(vm);
602 	return -ENOMEM;
603 }
604 
605 static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
606 {
607 	struct i915_address_space *vm = &ppgtt->vm;
608 	struct i915_page_directory *pd = ppgtt->pd;
609 	unsigned int idx;
610 
611 	GEM_BUG_ON(vm->top != 2);
612 	GEM_BUG_ON(gen8_pd_top_count(vm) != GEN8_3LVL_PDPES);
613 
614 	for (idx = 0; idx < GEN8_3LVL_PDPES; idx++) {
615 		struct i915_page_directory *pde;
616 
617 		pde = alloc_pd(vm);
618 		if (IS_ERR(pde))
619 			return PTR_ERR(pde);
620 
621 		fill_px(pde, vm->scratch[1].encode);
622 		set_pd_entry(pd, idx, pde);
623 		atomic_inc(px_used(pde)); /* keep pinned */
624 	}
625 	wmb();
626 
627 	return 0;
628 }
629 
630 static struct i915_page_directory *
631 gen8_alloc_top_pd(struct i915_address_space *vm)
632 {
633 	const unsigned int count = gen8_pd_top_count(vm);
634 	struct i915_page_directory *pd;
635 
636 	GEM_BUG_ON(count > ARRAY_SIZE(pd->entry));
637 
638 	pd = __alloc_pd(offsetof(typeof(*pd), entry[count]));
639 	if (unlikely(!pd))
640 		return ERR_PTR(-ENOMEM);
641 
642 	if (unlikely(setup_page_dma(vm, px_base(pd)))) {
643 		kfree(pd);
644 		return ERR_PTR(-ENOMEM);
645 	}
646 
647 	fill_page_dma(px_base(pd), vm->scratch[vm->top].encode, count);
648 	atomic_inc(px_used(pd)); /* mark as pinned */
649 	return pd;
650 }
651 
652 /*
653  * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
654  * with a net effect resembling a 2-level page table in normal x86 terms. Each
655  * PDP represents 1GB of memory 4 * 512 * 512 * 4096 = 4GB legacy 32b address
656  * space.
657  *
658  */
659 struct i915_ppgtt *gen8_ppgtt_create(struct intel_gt *gt)
660 {
661 	struct i915_ppgtt *ppgtt;
662 	int err;
663 
664 	ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
665 	if (!ppgtt)
666 		return ERR_PTR(-ENOMEM);
667 
668 	ppgtt_init(ppgtt, gt);
669 	ppgtt->vm.top = i915_vm_is_4lvl(&ppgtt->vm) ? 3 : 2;
670 
671 	/*
672 	 * From bdw, there is hw support for read-only pages in the PPGTT.
673 	 *
674 	 * Gen11 has HSDES#:1807136187 unresolved. Disable ro support
675 	 * for now.
676 	 *
677 	 * Gen12 has inherited the same read-only fault issue from gen11.
678 	 */
679 	ppgtt->vm.has_read_only = !IS_GEN_RANGE(gt->i915, 11, 12);
680 
681 	/*
682 	 * There are only few exceptions for gen >=6. chv and bxt.
683 	 * And we are not sure about the latter so play safe for now.
684 	 */
685 	if (IS_CHERRYVIEW(gt->i915) || IS_BROXTON(gt->i915))
686 		ppgtt->vm.pt_kmap_wc = true;
687 
688 	err = gen8_init_scratch(&ppgtt->vm);
689 	if (err)
690 		goto err_free;
691 
692 	ppgtt->pd = gen8_alloc_top_pd(&ppgtt->vm);
693 	if (IS_ERR(ppgtt->pd)) {
694 		err = PTR_ERR(ppgtt->pd);
695 		goto err_free_scratch;
696 	}
697 
698 	if (!i915_vm_is_4lvl(&ppgtt->vm)) {
699 		err = gen8_preallocate_top_level_pdp(ppgtt);
700 		if (err)
701 			goto err_free_pd;
702 	}
703 
704 	ppgtt->vm.bind_async_flags = I915_VMA_LOCAL_BIND;
705 	ppgtt->vm.insert_entries = gen8_ppgtt_insert;
706 	ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc;
707 	ppgtt->vm.clear_range = gen8_ppgtt_clear;
708 
709 	if (intel_vgpu_active(gt->i915))
710 		gen8_ppgtt_notify_vgt(ppgtt, true);
711 
712 	ppgtt->vm.cleanup = gen8_ppgtt_cleanup;
713 
714 	return ppgtt;
715 
716 err_free_pd:
717 	__gen8_ppgtt_cleanup(&ppgtt->vm, ppgtt->pd,
718 			     gen8_pd_top_count(&ppgtt->vm), ppgtt->vm.top);
719 err_free_scratch:
720 	free_scratch(&ppgtt->vm);
721 err_free:
722 	kfree(ppgtt);
723 	return ERR_PTR(err);
724 }
725