xref: /linux/arch/x86/kvm/mtrr.c (revision fbce3befd60d40639bf3c6b60f7477b2f988f92d) 
1 /*
2  * vMTRR implementation
3  *
4  * Copyright (C) 2006 Qumranet, Inc.
5  * Copyright 2010 Red Hat, Inc. and/or its affiliates.
6  * Copyright(C) 2015 Intel Corporation.
7  *
8  * Authors:
9  *   Yaniv Kamay  <yaniv@qumranet.com>
10  *   Avi Kivity   <avi@qumranet.com>
11  *   Marcelo Tosatti <mtosatti@redhat.com>
12  *   Paolo Bonzini <pbonzini@redhat.com>
13  *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
14  *
15  * This work is licensed under the terms of the GNU GPL, version 2.  See
16  * the COPYING file in the top-level directory.
17  */
18 
19 #include <linux/kvm_host.h>
20 #include <asm/mtrr.h>
21 
22 #include "cpuid.h"
23 #include "mmu.h"
24 
25 #define IA32_MTRR_DEF_TYPE_E		(1ULL << 11)
26 #define IA32_MTRR_DEF_TYPE_FE		(1ULL << 10)
27 #define IA32_MTRR_DEF_TYPE_TYPE_MASK	(0xff)
28 
29 static bool msr_mtrr_valid(unsigned msr)
30 {
31 	switch (msr) {
32 	case 0x200 ... 0x200 + 2 * KVM_NR_VAR_MTRR - 1:
33 	case MSR_MTRRfix64K_00000:
34 	case MSR_MTRRfix16K_80000:
35 	case MSR_MTRRfix16K_A0000:
36 	case MSR_MTRRfix4K_C0000:
37 	case MSR_MTRRfix4K_C8000:
38 	case MSR_MTRRfix4K_D0000:
39 	case MSR_MTRRfix4K_D8000:
40 	case MSR_MTRRfix4K_E0000:
41 	case MSR_MTRRfix4K_E8000:
42 	case MSR_MTRRfix4K_F0000:
43 	case MSR_MTRRfix4K_F8000:
44 	case MSR_MTRRdefType:
45 	case MSR_IA32_CR_PAT:
46 		return true;
47 	case 0x2f8:
48 		return true;
49 	}
50 	return false;
51 }
52 
53 static bool valid_pat_type(unsigned t)
54 {
55 	return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
56 }
57 
58 static bool valid_mtrr_type(unsigned t)
59 {
60 	return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
61 }
62 
63 bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
64 {
65 	int i;
66 	u64 mask;
67 
68 	if (!msr_mtrr_valid(msr))
69 		return false;
70 
71 	if (msr == MSR_IA32_CR_PAT) {
72 		for (i = 0; i < 8; i++)
73 			if (!valid_pat_type((data >> (i * 8)) & 0xff))
74 				return false;
75 		return true;
76 	} else if (msr == MSR_MTRRdefType) {
77 		if (data & ~0xcff)
78 			return false;
79 		return valid_mtrr_type(data & 0xff);
80 	} else if (msr >= MSR_MTRRfix64K_00000 && msr <= MSR_MTRRfix4K_F8000) {
81 		for (i = 0; i < 8 ; i++)
82 			if (!valid_mtrr_type((data >> (i * 8)) & 0xff))
83 				return false;
84 		return true;
85 	}
86 
87 	/* variable MTRRs */
88 	WARN_ON(!(msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR));
89 
90 	mask = (~0ULL) << cpuid_maxphyaddr(vcpu);
91 	if ((msr & 1) == 0) {
92 		/* MTRR base */
93 		if (!valid_mtrr_type(data & 0xff))
94 			return false;
95 		mask |= 0xf00;
96 	} else
97 		/* MTRR mask */
98 		mask |= 0x7ff;
99 	if (data & mask) {
100 		kvm_inject_gp(vcpu, 0);
101 		return false;
102 	}
103 
104 	return true;
105 }
106 EXPORT_SYMBOL_GPL(kvm_mtrr_valid);
107 
108 static bool mtrr_is_enabled(struct kvm_mtrr *mtrr_state)
109 {
110 	return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_E);
111 }
112 
113 static bool fixed_mtrr_is_enabled(struct kvm_mtrr *mtrr_state)
114 {
115 	return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_FE);
116 }
117 
118 static u8 mtrr_default_type(struct kvm_mtrr *mtrr_state)
119 {
120 	return mtrr_state->deftype & IA32_MTRR_DEF_TYPE_TYPE_MASK;
121 }
122 
123 static u8 mtrr_disabled_type(struct kvm_vcpu *vcpu)
124 {
125 	/*
126 	 * Intel SDM 11.11.2.2: all MTRRs are disabled when
127 	 * IA32_MTRR_DEF_TYPE.E bit is cleared, and the UC
128 	 * memory type is applied to all of physical memory.
129 	 *
130 	 * However, virtual machines can be run with CPUID such that
131 	 * there are no MTRRs.  In that case, the firmware will never
132 	 * enable MTRRs and it is obviously undesirable to run the
133 	 * guest entirely with UC memory and we use WB.
134 	 */
135 	if (guest_cpuid_has_mtrr(vcpu))
136 		return MTRR_TYPE_UNCACHABLE;
137 	else
138 		return MTRR_TYPE_WRBACK;
139 }
140 
141 /*
142 * Three terms are used in the following code:
143 * - segment, it indicates the address segments covered by fixed MTRRs.
144 * - unit, it corresponds to the MSR entry in the segment.
145 * - range, a range is covered in one memory cache type.
146 */
147 struct fixed_mtrr_segment {
148 	u64 start;
149 	u64 end;
150 
151 	int range_shift;
152 
153 	/* the start position in kvm_mtrr.fixed_ranges[]. */
154 	int range_start;
155 };
156 
157 static struct fixed_mtrr_segment fixed_seg_table[] = {
158 	/* MSR_MTRRfix64K_00000, 1 unit. 64K fixed mtrr. */
159 	{
160 		.start = 0x0,
161 		.end = 0x80000,
162 		.range_shift = 16, /* 64K */
163 		.range_start = 0,
164 	},
165 
166 	/*
167 	 * MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000, 2 units,
168 	 * 16K fixed mtrr.
169 	 */
170 	{
171 		.start = 0x80000,
172 		.end = 0xc0000,
173 		.range_shift = 14, /* 16K */
174 		.range_start = 8,
175 	},
176 
177 	/*
178 	 * MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000, 8 units,
179 	 * 4K fixed mtrr.
180 	 */
181 	{
182 		.start = 0xc0000,
183 		.end = 0x100000,
184 		.range_shift = 12, /* 12K */
185 		.range_start = 24,
186 	}
187 };
188 
189 /*
190  * The size of unit is covered in one MSR, one MSR entry contains
191  * 8 ranges so that unit size is always 8 * 2^range_shift.
192  */
193 static u64 fixed_mtrr_seg_unit_size(int seg)
194 {
195 	return 8 << fixed_seg_table[seg].range_shift;
196 }
197 
198 static bool fixed_msr_to_seg_unit(u32 msr, int *seg, int *unit)
199 {
200 	switch (msr) {
201 	case MSR_MTRRfix64K_00000:
202 		*seg = 0;
203 		*unit = 0;
204 		break;
205 	case MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000:
206 		*seg = 1;
207 		*unit = msr - MSR_MTRRfix16K_80000;
208 		break;
209 	case MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000:
210 		*seg = 2;
211 		*unit = msr - MSR_MTRRfix4K_C0000;
212 		break;
213 	default:
214 		return false;
215 	}
216 
217 	return true;
218 }
219 
220 static void fixed_mtrr_seg_unit_range(int seg, int unit, u64 *start, u64 *end)
221 {
222 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
223 	u64 unit_size = fixed_mtrr_seg_unit_size(seg);
224 
225 	*start = mtrr_seg->start + unit * unit_size;
226 	*end = *start + unit_size;
227 	WARN_ON(*end > mtrr_seg->end);
228 }
229 
230 static int fixed_mtrr_seg_unit_range_index(int seg, int unit)
231 {
232 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
233 
234 	WARN_ON(mtrr_seg->start + unit * fixed_mtrr_seg_unit_size(seg)
235 		> mtrr_seg->end);
236 
237 	/* each unit has 8 ranges. */
238 	return mtrr_seg->range_start + 8 * unit;
239 }
240 
241 static int fixed_mtrr_seg_end_range_index(int seg)
242 {
243 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
244 	int n;
245 
246 	n = (mtrr_seg->end - mtrr_seg->start) >> mtrr_seg->range_shift;
247 	return mtrr_seg->range_start + n - 1;
248 }
249 
250 static bool fixed_msr_to_range(u32 msr, u64 *start, u64 *end)
251 {
252 	int seg, unit;
253 
254 	if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
255 		return false;
256 
257 	fixed_mtrr_seg_unit_range(seg, unit, start, end);
258 	return true;
259 }
260 
261 static int fixed_msr_to_range_index(u32 msr)
262 {
263 	int seg, unit;
264 
265 	if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
266 		return -1;
267 
268 	return fixed_mtrr_seg_unit_range_index(seg, unit);
269 }
270 
271 static int fixed_mtrr_addr_to_seg(u64 addr)
272 {
273 	struct fixed_mtrr_segment *mtrr_seg;
274 	int seg, seg_num = ARRAY_SIZE(fixed_seg_table);
275 
276 	for (seg = 0; seg < seg_num; seg++) {
277 		mtrr_seg = &fixed_seg_table[seg];
278 		if (mtrr_seg->start <= addr && addr < mtrr_seg->end)
279 			return seg;
280 	}
281 
282 	return -1;
283 }
284 
285 static int fixed_mtrr_addr_seg_to_range_index(u64 addr, int seg)
286 {
287 	struct fixed_mtrr_segment *mtrr_seg;
288 	int index;
289 
290 	mtrr_seg = &fixed_seg_table[seg];
291 	index = mtrr_seg->range_start;
292 	index += (addr - mtrr_seg->start) >> mtrr_seg->range_shift;
293 	return index;
294 }
295 
296 static u64 fixed_mtrr_range_end_addr(int seg, int index)
297 {
298 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
299 	int pos = index - mtrr_seg->range_start;
300 
301 	return mtrr_seg->start + ((pos + 1) << mtrr_seg->range_shift);
302 }
303 
304 static void var_mtrr_range(struct kvm_mtrr_range *range, u64 *start, u64 *end)
305 {
306 	u64 mask;
307 
308 	*start = range->base & PAGE_MASK;
309 
310 	mask = range->mask & PAGE_MASK;
311 
312 	/* This cannot overflow because writing to the reserved bits of
313 	 * variable MTRRs causes a #GP.
314 	 */
315 	*end = (*start | ~mask) + 1;
316 }
317 
318 static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
319 {
320 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
321 	gfn_t start, end;
322 	int index;
323 
324 	if (msr == MSR_IA32_CR_PAT || !tdp_enabled ||
325 	      !kvm_arch_has_noncoherent_dma(vcpu->kvm))
326 		return;
327 
328 	if (!mtrr_is_enabled(mtrr_state) && msr != MSR_MTRRdefType)
329 		return;
330 
331 	/* fixed MTRRs. */
332 	if (fixed_msr_to_range(msr, &start, &end)) {
333 		if (!fixed_mtrr_is_enabled(mtrr_state))
334 			return;
335 	} else if (msr == MSR_MTRRdefType) {
336 		start = 0x0;
337 		end = ~0ULL;
338 	} else {
339 		/* variable range MTRRs. */
340 		index = (msr - 0x200) / 2;
341 		var_mtrr_range(&mtrr_state->var_ranges[index], &start, &end);
342 	}
343 
344 	kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));
345 }
346 
347 static bool var_mtrr_range_is_valid(struct kvm_mtrr_range *range)
348 {
349 	return (range->mask & (1 << 11)) != 0;
350 }
351 
352 static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
353 {
354 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
355 	struct kvm_mtrr_range *tmp, *cur;
356 	int index, is_mtrr_mask;
357 
358 	index = (msr - 0x200) / 2;
359 	is_mtrr_mask = msr - 0x200 - 2 * index;
360 	cur = &mtrr_state->var_ranges[index];
361 
362 	/* remove the entry if it's in the list. */
363 	if (var_mtrr_range_is_valid(cur))
364 		list_del(&mtrr_state->var_ranges[index].node);
365 
366 	/* Extend the mask with all 1 bits to the left, since those
367 	 * bits must implicitly be 0.  The bits are then cleared
368 	 * when reading them.
369 	 */
370 	if (!is_mtrr_mask)
371 		cur->base = data;
372 	else
373 		cur->mask = data | (-1LL << cpuid_maxphyaddr(vcpu));
374 
375 	/* add it to the list if it's enabled. */
376 	if (var_mtrr_range_is_valid(cur)) {
377 		list_for_each_entry(tmp, &mtrr_state->head, node)
378 			if (cur->base >= tmp->base)
379 				break;
380 		list_add_tail(&cur->node, &tmp->node);
381 	}
382 }
383 
384 int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
385 {
386 	int index;
387 
388 	if (!kvm_mtrr_valid(vcpu, msr, data))
389 		return 1;
390 
391 	index = fixed_msr_to_range_index(msr);
392 	if (index >= 0)
393 		*(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index] = data;
394 	else if (msr == MSR_MTRRdefType)
395 		vcpu->arch.mtrr_state.deftype = data;
396 	else if (msr == MSR_IA32_CR_PAT)
397 		vcpu->arch.pat = data;
398 	else
399 		set_var_mtrr_msr(vcpu, msr, data);
400 
401 	update_mtrr(vcpu, msr);
402 	return 0;
403 }
404 
405 int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
406 {
407 	int index;
408 
409 	/* MSR_MTRRcap is a readonly MSR. */
410 	if (msr == MSR_MTRRcap) {
411 		/*
412 		 * SMRR = 0
413 		 * WC = 1
414 		 * FIX = 1
415 		 * VCNT = KVM_NR_VAR_MTRR
416 		 */
417 		*pdata = 0x500 | KVM_NR_VAR_MTRR;
418 		return 0;
419 	}
420 
421 	if (!msr_mtrr_valid(msr))
422 		return 1;
423 
424 	index = fixed_msr_to_range_index(msr);
425 	if (index >= 0)
426 		*pdata = *(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index];
427 	else if (msr == MSR_MTRRdefType)
428 		*pdata = vcpu->arch.mtrr_state.deftype;
429 	else if (msr == MSR_IA32_CR_PAT)
430 		*pdata = vcpu->arch.pat;
431 	else {	/* Variable MTRRs */
432 		int is_mtrr_mask;
433 
434 		index = (msr - 0x200) / 2;
435 		is_mtrr_mask = msr - 0x200 - 2 * index;
436 		if (!is_mtrr_mask)
437 			*pdata = vcpu->arch.mtrr_state.var_ranges[index].base;
438 		else
439 			*pdata = vcpu->arch.mtrr_state.var_ranges[index].mask;
440 
441 		*pdata &= (1ULL << cpuid_maxphyaddr(vcpu)) - 1;
442 	}
443 
444 	return 0;
445 }
446 
447 void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu)
448 {
449 	INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head);
450 }
451 
452 struct mtrr_iter {
453 	/* input fields. */
454 	struct kvm_mtrr *mtrr_state;
455 	u64 start;
456 	u64 end;
457 
458 	/* output fields. */
459 	int mem_type;
460 	/* mtrr is completely disabled? */
461 	bool mtrr_disabled;
462 	/* [start, end) is not fully covered in MTRRs? */
463 	bool partial_map;
464 
465 	/* private fields. */
466 	union {
467 		/* used for fixed MTRRs. */
468 		struct {
469 			int index;
470 			int seg;
471 		};
472 
473 		/* used for var MTRRs. */
474 		struct {
475 			struct kvm_mtrr_range *range;
476 			/* max address has been covered in var MTRRs. */
477 			u64 start_max;
478 		};
479 	};
480 
481 	bool fixed;
482 };
483 
484 static bool mtrr_lookup_fixed_start(struct mtrr_iter *iter)
485 {
486 	int seg, index;
487 
488 	if (!fixed_mtrr_is_enabled(iter->mtrr_state))
489 		return false;
490 
491 	seg = fixed_mtrr_addr_to_seg(iter->start);
492 	if (seg < 0)
493 		return false;
494 
495 	iter->fixed = true;
496 	index = fixed_mtrr_addr_seg_to_range_index(iter->start, seg);
497 	iter->index = index;
498 	iter->seg = seg;
499 	return true;
500 }
501 
502 static bool match_var_range(struct mtrr_iter *iter,
503 			    struct kvm_mtrr_range *range)
504 {
505 	u64 start, end;
506 
507 	var_mtrr_range(range, &start, &end);
508 	if (!(start >= iter->end || end <= iter->start)) {
509 		iter->range = range;
510 
511 		/*
512 		 * the function is called when we do kvm_mtrr.head walking.
513 		 * Range has the minimum base address which interleaves
514 		 * [looker->start_max, looker->end).
515 		 */
516 		iter->partial_map |= iter->start_max < start;
517 
518 		/* update the max address has been covered. */
519 		iter->start_max = max(iter->start_max, end);
520 		return true;
521 	}
522 
523 	return false;
524 }
525 
526 static void __mtrr_lookup_var_next(struct mtrr_iter *iter)
527 {
528 	struct kvm_mtrr *mtrr_state = iter->mtrr_state;
529 
530 	list_for_each_entry_continue(iter->range, &mtrr_state->head, node)
531 		if (match_var_range(iter, iter->range))
532 			return;
533 
534 	iter->range = NULL;
535 	iter->partial_map |= iter->start_max < iter->end;
536 }
537 
538 static void mtrr_lookup_var_start(struct mtrr_iter *iter)
539 {
540 	struct kvm_mtrr *mtrr_state = iter->mtrr_state;
541 
542 	iter->fixed = false;
543 	iter->start_max = iter->start;
544 	iter->range = list_prepare_entry(iter->range, &mtrr_state->head, node);
545 
546 	__mtrr_lookup_var_next(iter);
547 }
548 
549 static void mtrr_lookup_fixed_next(struct mtrr_iter *iter)
550 {
551 	/* terminate the lookup. */
552 	if (fixed_mtrr_range_end_addr(iter->seg, iter->index) >= iter->end) {
553 		iter->fixed = false;
554 		iter->range = NULL;
555 		return;
556 	}
557 
558 	iter->index++;
559 
560 	/* have looked up for all fixed MTRRs. */
561 	if (iter->index >= ARRAY_SIZE(iter->mtrr_state->fixed_ranges))
562 		return mtrr_lookup_var_start(iter);
563 
564 	/* switch to next segment. */
565 	if (iter->index > fixed_mtrr_seg_end_range_index(iter->seg))
566 		iter->seg++;
567 }
568 
569 static void mtrr_lookup_var_next(struct mtrr_iter *iter)
570 {
571 	__mtrr_lookup_var_next(iter);
572 }
573 
574 static void mtrr_lookup_start(struct mtrr_iter *iter)
575 {
576 	if (!mtrr_is_enabled(iter->mtrr_state)) {
577 		iter->mtrr_disabled = true;
578 		return;
579 	}
580 
581 	if (!mtrr_lookup_fixed_start(iter))
582 		mtrr_lookup_var_start(iter);
583 }
584 
585 static void mtrr_lookup_init(struct mtrr_iter *iter,
586 			     struct kvm_mtrr *mtrr_state, u64 start, u64 end)
587 {
588 	iter->mtrr_state = mtrr_state;
589 	iter->start = start;
590 	iter->end = end;
591 	iter->mtrr_disabled = false;
592 	iter->partial_map = false;
593 	iter->fixed = false;
594 	iter->range = NULL;
595 
596 	mtrr_lookup_start(iter);
597 }
598 
599 static bool mtrr_lookup_okay(struct mtrr_iter *iter)
600 {
601 	if (iter->fixed) {
602 		iter->mem_type = iter->mtrr_state->fixed_ranges[iter->index];
603 		return true;
604 	}
605 
606 	if (iter->range) {
607 		iter->mem_type = iter->range->base & 0xff;
608 		return true;
609 	}
610 
611 	return false;
612 }
613 
614 static void mtrr_lookup_next(struct mtrr_iter *iter)
615 {
616 	if (iter->fixed)
617 		mtrr_lookup_fixed_next(iter);
618 	else
619 		mtrr_lookup_var_next(iter);
620 }
621 
622 #define mtrr_for_each_mem_type(_iter_, _mtrr_, _gpa_start_, _gpa_end_) \
623 	for (mtrr_lookup_init(_iter_, _mtrr_, _gpa_start_, _gpa_end_); \
624 	     mtrr_lookup_okay(_iter_); mtrr_lookup_next(_iter_))
625 
626 u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
627 {
628 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
629 	struct mtrr_iter iter;
630 	u64 start, end;
631 	int type = -1;
632 	const int wt_wb_mask = (1 << MTRR_TYPE_WRBACK)
633 			       | (1 << MTRR_TYPE_WRTHROUGH);
634 
635 	start = gfn_to_gpa(gfn);
636 	end = start + PAGE_SIZE;
637 
638 	mtrr_for_each_mem_type(&iter, mtrr_state, start, end) {
639 		int curr_type = iter.mem_type;
640 
641 		/*
642 		 * Please refer to Intel SDM Volume 3: 11.11.4.1 MTRR
643 		 * Precedences.
644 		 */
645 
646 		if (type == -1) {
647 			type = curr_type;
648 			continue;
649 		}
650 
651 		/*
652 		 * If two or more variable memory ranges match and the
653 		 * memory types are identical, then that memory type is
654 		 * used.
655 		 */
656 		if (type == curr_type)
657 			continue;
658 
659 		/*
660 		 * If two or more variable memory ranges match and one of
661 		 * the memory types is UC, the UC memory type used.
662 		 */
663 		if (curr_type == MTRR_TYPE_UNCACHABLE)
664 			return MTRR_TYPE_UNCACHABLE;
665 
666 		/*
667 		 * If two or more variable memory ranges match and the
668 		 * memory types are WT and WB, the WT memory type is used.
669 		 */
670 		if (((1 << type) & wt_wb_mask) &&
671 		      ((1 << curr_type) & wt_wb_mask)) {
672 			type = MTRR_TYPE_WRTHROUGH;
673 			continue;
674 		}
675 
676 		/*
677 		 * For overlaps not defined by the above rules, processor
678 		 * behavior is undefined.
679 		 */
680 
681 		/* We use WB for this undefined behavior. :( */
682 		return MTRR_TYPE_WRBACK;
683 	}
684 
685 	if (iter.mtrr_disabled)
686 		return mtrr_disabled_type(vcpu);
687 
688 	/* not contained in any MTRRs. */
689 	if (type == -1)
690 		return mtrr_default_type(mtrr_state);
691 
692 	/*
693 	 * We just check one page, partially covered by MTRRs is
694 	 * impossible.
695 	 */
696 	WARN_ON(iter.partial_map);
697 
698 	return type;
699 }
700 EXPORT_SYMBOL_GPL(kvm_mtrr_get_guest_memory_type);
701 
702 bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
703 					  int page_num)
704 {
705 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
706 	struct mtrr_iter iter;
707 	u64 start, end;
708 	int type = -1;
709 
710 	start = gfn_to_gpa(gfn);
711 	end = gfn_to_gpa(gfn + page_num);
712 	mtrr_for_each_mem_type(&iter, mtrr_state, start, end) {
713 		if (type == -1) {
714 			type = iter.mem_type;
715 			continue;
716 		}
717 
718 		if (type != iter.mem_type)
719 			return false;
720 	}
721 
722 	if (iter.mtrr_disabled)
723 		return true;
724 
725 	if (!iter.partial_map)
726 		return true;
727 
728 	if (type == -1)
729 		return true;
730 
731 	return type == mtrr_default_type(mtrr_state);
732 }
733