xref: /openbmc/linux/arch/x86/kvm/mtrr.c (revision 5b394b2d) 
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 	}
48 	return false;
49 }
50 
51 static bool valid_pat_type(unsigned t)
52 {
53 	return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
54 }
55 
56 static bool valid_mtrr_type(unsigned t)
57 {
58 	return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
59 }
60 
61 bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
62 {
63 	int i;
64 	u64 mask;
65 
66 	if (!msr_mtrr_valid(msr))
67 		return false;
68 
69 	if (msr == MSR_IA32_CR_PAT) {
70 		for (i = 0; i < 8; i++)
71 			if (!valid_pat_type((data >> (i * 8)) & 0xff))
72 				return false;
73 		return true;
74 	} else if (msr == MSR_MTRRdefType) {
75 		if (data & ~0xcff)
76 			return false;
77 		return valid_mtrr_type(data & 0xff);
78 	} else if (msr >= MSR_MTRRfix64K_00000 && msr <= MSR_MTRRfix4K_F8000) {
79 		for (i = 0; i < 8 ; i++)
80 			if (!valid_mtrr_type((data >> (i * 8)) & 0xff))
81 				return false;
82 		return true;
83 	}
84 
85 	/* variable MTRRs */
86 	WARN_ON(!(msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR));
87 
88 	mask = (~0ULL) << cpuid_maxphyaddr(vcpu);
89 	if ((msr & 1) == 0) {
90 		/* MTRR base */
91 		if (!valid_mtrr_type(data & 0xff))
92 			return false;
93 		mask |= 0xf00;
94 	} else
95 		/* MTRR mask */
96 		mask |= 0x7ff;
97 	if (data & mask) {
98 		kvm_inject_gp(vcpu, 0);
99 		return false;
100 	}
101 
102 	return true;
103 }
104 EXPORT_SYMBOL_GPL(kvm_mtrr_valid);
105 
106 static bool mtrr_is_enabled(struct kvm_mtrr *mtrr_state)
107 {
108 	return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_E);
109 }
110 
111 static bool fixed_mtrr_is_enabled(struct kvm_mtrr *mtrr_state)
112 {
113 	return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_FE);
114 }
115 
116 static u8 mtrr_default_type(struct kvm_mtrr *mtrr_state)
117 {
118 	return mtrr_state->deftype & IA32_MTRR_DEF_TYPE_TYPE_MASK;
119 }
120 
121 static u8 mtrr_disabled_type(struct kvm_vcpu *vcpu)
122 {
123 	/*
124 	 * Intel SDM 11.11.2.2: all MTRRs are disabled when
125 	 * IA32_MTRR_DEF_TYPE.E bit is cleared, and the UC
126 	 * memory type is applied to all of physical memory.
127 	 *
128 	 * However, virtual machines can be run with CPUID such that
129 	 * there are no MTRRs.  In that case, the firmware will never
130 	 * enable MTRRs and it is obviously undesirable to run the
131 	 * guest entirely with UC memory and we use WB.
132 	 */
133 	if (guest_cpuid_has(vcpu, X86_FEATURE_MTRR))
134 		return MTRR_TYPE_UNCACHABLE;
135 	else
136 		return MTRR_TYPE_WRBACK;
137 }
138 
139 /*
140 * Three terms are used in the following code:
141 * - segment, it indicates the address segments covered by fixed MTRRs.
142 * - unit, it corresponds to the MSR entry in the segment.
143 * - range, a range is covered in one memory cache type.
144 */
145 struct fixed_mtrr_segment {
146 	u64 start;
147 	u64 end;
148 
149 	int range_shift;
150 
151 	/* the start position in kvm_mtrr.fixed_ranges[]. */
152 	int range_start;
153 };
154 
155 static struct fixed_mtrr_segment fixed_seg_table[] = {
156 	/* MSR_MTRRfix64K_00000, 1 unit. 64K fixed mtrr. */
157 	{
158 		.start = 0x0,
159 		.end = 0x80000,
160 		.range_shift = 16, /* 64K */
161 		.range_start = 0,
162 	},
163 
164 	/*
165 	 * MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000, 2 units,
166 	 * 16K fixed mtrr.
167 	 */
168 	{
169 		.start = 0x80000,
170 		.end = 0xc0000,
171 		.range_shift = 14, /* 16K */
172 		.range_start = 8,
173 	},
174 
175 	/*
176 	 * MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000, 8 units,
177 	 * 4K fixed mtrr.
178 	 */
179 	{
180 		.start = 0xc0000,
181 		.end = 0x100000,
182 		.range_shift = 12, /* 12K */
183 		.range_start = 24,
184 	}
185 };
186 
187 /*
188  * The size of unit is covered in one MSR, one MSR entry contains
189  * 8 ranges so that unit size is always 8 * 2^range_shift.
190  */
191 static u64 fixed_mtrr_seg_unit_size(int seg)
192 {
193 	return 8 << fixed_seg_table[seg].range_shift;
194 }
195 
196 static bool fixed_msr_to_seg_unit(u32 msr, int *seg, int *unit)
197 {
198 	switch (msr) {
199 	case MSR_MTRRfix64K_00000:
200 		*seg = 0;
201 		*unit = 0;
202 		break;
203 	case MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000:
204 		*seg = 1;
205 		*unit = msr - MSR_MTRRfix16K_80000;
206 		break;
207 	case MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000:
208 		*seg = 2;
209 		*unit = msr - MSR_MTRRfix4K_C0000;
210 		break;
211 	default:
212 		return false;
213 	}
214 
215 	return true;
216 }
217 
218 static void fixed_mtrr_seg_unit_range(int seg, int unit, u64 *start, u64 *end)
219 {
220 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
221 	u64 unit_size = fixed_mtrr_seg_unit_size(seg);
222 
223 	*start = mtrr_seg->start + unit * unit_size;
224 	*end = *start + unit_size;
225 	WARN_ON(*end > mtrr_seg->end);
226 }
227 
228 static int fixed_mtrr_seg_unit_range_index(int seg, int unit)
229 {
230 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
231 
232 	WARN_ON(mtrr_seg->start + unit * fixed_mtrr_seg_unit_size(seg)
233 		> mtrr_seg->end);
234 
235 	/* each unit has 8 ranges. */
236 	return mtrr_seg->range_start + 8 * unit;
237 }
238 
239 static int fixed_mtrr_seg_end_range_index(int seg)
240 {
241 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
242 	int n;
243 
244 	n = (mtrr_seg->end - mtrr_seg->start) >> mtrr_seg->range_shift;
245 	return mtrr_seg->range_start + n - 1;
246 }
247 
248 static bool fixed_msr_to_range(u32 msr, u64 *start, u64 *end)
249 {
250 	int seg, unit;
251 
252 	if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
253 		return false;
254 
255 	fixed_mtrr_seg_unit_range(seg, unit, start, end);
256 	return true;
257 }
258 
259 static int fixed_msr_to_range_index(u32 msr)
260 {
261 	int seg, unit;
262 
263 	if (!fixed_msr_to_seg_unit(msr, &seg, &unit))
264 		return -1;
265 
266 	return fixed_mtrr_seg_unit_range_index(seg, unit);
267 }
268 
269 static int fixed_mtrr_addr_to_seg(u64 addr)
270 {
271 	struct fixed_mtrr_segment *mtrr_seg;
272 	int seg, seg_num = ARRAY_SIZE(fixed_seg_table);
273 
274 	for (seg = 0; seg < seg_num; seg++) {
275 		mtrr_seg = &fixed_seg_table[seg];
276 		if (mtrr_seg->start <= addr && addr < mtrr_seg->end)
277 			return seg;
278 	}
279 
280 	return -1;
281 }
282 
283 static int fixed_mtrr_addr_seg_to_range_index(u64 addr, int seg)
284 {
285 	struct fixed_mtrr_segment *mtrr_seg;
286 	int index;
287 
288 	mtrr_seg = &fixed_seg_table[seg];
289 	index = mtrr_seg->range_start;
290 	index += (addr - mtrr_seg->start) >> mtrr_seg->range_shift;
291 	return index;
292 }
293 
294 static u64 fixed_mtrr_range_end_addr(int seg, int index)
295 {
296 	struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg];
297 	int pos = index - mtrr_seg->range_start;
298 
299 	return mtrr_seg->start + ((pos + 1) << mtrr_seg->range_shift);
300 }
301 
302 static void var_mtrr_range(struct kvm_mtrr_range *range, u64 *start, u64 *end)
303 {
304 	u64 mask;
305 
306 	*start = range->base & PAGE_MASK;
307 
308 	mask = range->mask & PAGE_MASK;
309 
310 	/* This cannot overflow because writing to the reserved bits of
311 	 * variable MTRRs causes a #GP.
312 	 */
313 	*end = (*start | ~mask) + 1;
314 }
315 
316 static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
317 {
318 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
319 	gfn_t start, end;
320 	int index;
321 
322 	if (msr == MSR_IA32_CR_PAT || !tdp_enabled ||
323 	      !kvm_arch_has_noncoherent_dma(vcpu->kvm))
324 		return;
325 
326 	if (!mtrr_is_enabled(mtrr_state) && msr != MSR_MTRRdefType)
327 		return;
328 
329 	/* fixed MTRRs. */
330 	if (fixed_msr_to_range(msr, &start, &end)) {
331 		if (!fixed_mtrr_is_enabled(mtrr_state))
332 			return;
333 	} else if (msr == MSR_MTRRdefType) {
334 		start = 0x0;
335 		end = ~0ULL;
336 	} else {
337 		/* variable range MTRRs. */
338 		index = (msr - 0x200) / 2;
339 		var_mtrr_range(&mtrr_state->var_ranges[index], &start, &end);
340 	}
341 
342 	kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));
343 }
344 
345 static bool var_mtrr_range_is_valid(struct kvm_mtrr_range *range)
346 {
347 	return (range->mask & (1 << 11)) != 0;
348 }
349 
350 static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
351 {
352 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
353 	struct kvm_mtrr_range *tmp, *cur;
354 	int index, is_mtrr_mask;
355 
356 	index = (msr - 0x200) / 2;
357 	is_mtrr_mask = msr - 0x200 - 2 * index;
358 	cur = &mtrr_state->var_ranges[index];
359 
360 	/* remove the entry if it's in the list. */
361 	if (var_mtrr_range_is_valid(cur))
362 		list_del(&mtrr_state->var_ranges[index].node);
363 
364 	/* Extend the mask with all 1 bits to the left, since those
365 	 * bits must implicitly be 0.  The bits are then cleared
366 	 * when reading them.
367 	 */
368 	if (!is_mtrr_mask)
369 		cur->base = data;
370 	else
371 		cur->mask = data | (-1LL << cpuid_maxphyaddr(vcpu));
372 
373 	/* add it to the list if it's enabled. */
374 	if (var_mtrr_range_is_valid(cur)) {
375 		list_for_each_entry(tmp, &mtrr_state->head, node)
376 			if (cur->base >= tmp->base)
377 				break;
378 		list_add_tail(&cur->node, &tmp->node);
379 	}
380 }
381 
382 int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
383 {
384 	int index;
385 
386 	if (!kvm_mtrr_valid(vcpu, msr, data))
387 		return 1;
388 
389 	index = fixed_msr_to_range_index(msr);
390 	if (index >= 0)
391 		*(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index] = data;
392 	else if (msr == MSR_MTRRdefType)
393 		vcpu->arch.mtrr_state.deftype = data;
394 	else if (msr == MSR_IA32_CR_PAT)
395 		vcpu->arch.pat = data;
396 	else
397 		set_var_mtrr_msr(vcpu, msr, data);
398 
399 	update_mtrr(vcpu, msr);
400 	return 0;
401 }
402 
403 int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
404 {
405 	int index;
406 
407 	/* MSR_MTRRcap is a readonly MSR. */
408 	if (msr == MSR_MTRRcap) {
409 		/*
410 		 * SMRR = 0
411 		 * WC = 1
412 		 * FIX = 1
413 		 * VCNT = KVM_NR_VAR_MTRR
414 		 */
415 		*pdata = 0x500 | KVM_NR_VAR_MTRR;
416 		return 0;
417 	}
418 
419 	if (!msr_mtrr_valid(msr))
420 		return 1;
421 
422 	index = fixed_msr_to_range_index(msr);
423 	if (index >= 0)
424 		*pdata = *(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index];
425 	else if (msr == MSR_MTRRdefType)
426 		*pdata = vcpu->arch.mtrr_state.deftype;
427 	else if (msr == MSR_IA32_CR_PAT)
428 		*pdata = vcpu->arch.pat;
429 	else {	/* Variable MTRRs */
430 		int is_mtrr_mask;
431 
432 		index = (msr - 0x200) / 2;
433 		is_mtrr_mask = msr - 0x200 - 2 * index;
434 		if (!is_mtrr_mask)
435 			*pdata = vcpu->arch.mtrr_state.var_ranges[index].base;
436 		else
437 			*pdata = vcpu->arch.mtrr_state.var_ranges[index].mask;
438 
439 		*pdata &= (1ULL << cpuid_maxphyaddr(vcpu)) - 1;
440 	}
441 
442 	return 0;
443 }
444 
445 void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu)
446 {
447 	INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head);
448 }
449 
450 struct mtrr_iter {
451 	/* input fields. */
452 	struct kvm_mtrr *mtrr_state;
453 	u64 start;
454 	u64 end;
455 
456 	/* output fields. */
457 	int mem_type;
458 	/* mtrr is completely disabled? */
459 	bool mtrr_disabled;
460 	/* [start, end) is not fully covered in MTRRs? */
461 	bool partial_map;
462 
463 	/* private fields. */
464 	union {
465 		/* used for fixed MTRRs. */
466 		struct {
467 			int index;
468 			int seg;
469 		};
470 
471 		/* used for var MTRRs. */
472 		struct {
473 			struct kvm_mtrr_range *range;
474 			/* max address has been covered in var MTRRs. */
475 			u64 start_max;
476 		};
477 	};
478 
479 	bool fixed;
480 };
481 
482 static bool mtrr_lookup_fixed_start(struct mtrr_iter *iter)
483 {
484 	int seg, index;
485 
486 	if (!fixed_mtrr_is_enabled(iter->mtrr_state))
487 		return false;
488 
489 	seg = fixed_mtrr_addr_to_seg(iter->start);
490 	if (seg < 0)
491 		return false;
492 
493 	iter->fixed = true;
494 	index = fixed_mtrr_addr_seg_to_range_index(iter->start, seg);
495 	iter->index = index;
496 	iter->seg = seg;
497 	return true;
498 }
499 
500 static bool match_var_range(struct mtrr_iter *iter,
501 			    struct kvm_mtrr_range *range)
502 {
503 	u64 start, end;
504 
505 	var_mtrr_range(range, &start, &end);
506 	if (!(start >= iter->end || end <= iter->start)) {
507 		iter->range = range;
508 
509 		/*
510 		 * the function is called when we do kvm_mtrr.head walking.
511 		 * Range has the minimum base address which interleaves
512 		 * [looker->start_max, looker->end).
513 		 */
514 		iter->partial_map |= iter->start_max < start;
515 
516 		/* update the max address has been covered. */
517 		iter->start_max = max(iter->start_max, end);
518 		return true;
519 	}
520 
521 	return false;
522 }
523 
524 static void __mtrr_lookup_var_next(struct mtrr_iter *iter)
525 {
526 	struct kvm_mtrr *mtrr_state = iter->mtrr_state;
527 
528 	list_for_each_entry_continue(iter->range, &mtrr_state->head, node)
529 		if (match_var_range(iter, iter->range))
530 			return;
531 
532 	iter->range = NULL;
533 	iter->partial_map |= iter->start_max < iter->end;
534 }
535 
536 static void mtrr_lookup_var_start(struct mtrr_iter *iter)
537 {
538 	struct kvm_mtrr *mtrr_state = iter->mtrr_state;
539 
540 	iter->fixed = false;
541 	iter->start_max = iter->start;
542 	iter->range = NULL;
543 	iter->range = list_prepare_entry(iter->range, &mtrr_state->head, node);
544 
545 	__mtrr_lookup_var_next(iter);
546 }
547 
548 static void mtrr_lookup_fixed_next(struct mtrr_iter *iter)
549 {
550 	/* terminate the lookup. */
551 	if (fixed_mtrr_range_end_addr(iter->seg, iter->index) >= iter->end) {
552 		iter->fixed = false;
553 		iter->range = NULL;
554 		return;
555 	}
556 
557 	iter->index++;
558 
559 	/* have looked up for all fixed MTRRs. */
560 	if (iter->index >= ARRAY_SIZE(iter->mtrr_state->fixed_ranges))
561 		return mtrr_lookup_var_start(iter);
562 
563 	/* switch to next segment. */
564 	if (iter->index > fixed_mtrr_seg_end_range_index(iter->seg))
565 		iter->seg++;
566 }
567 
568 static void mtrr_lookup_var_next(struct mtrr_iter *iter)
569 {
570 	__mtrr_lookup_var_next(iter);
571 }
572 
573 static void mtrr_lookup_start(struct mtrr_iter *iter)
574 {
575 	if (!mtrr_is_enabled(iter->mtrr_state)) {
576 		iter->mtrr_disabled = true;
577 		return;
578 	}
579 
580 	if (!mtrr_lookup_fixed_start(iter))
581 		mtrr_lookup_var_start(iter);
582 }
583 
584 static void mtrr_lookup_init(struct mtrr_iter *iter,
585 			     struct kvm_mtrr *mtrr_state, u64 start, u64 end)
586 {
587 	iter->mtrr_state = mtrr_state;
588 	iter->start = start;
589 	iter->end = end;
590 	iter->mtrr_disabled = false;
591 	iter->partial_map = false;
592 	iter->fixed = false;
593 	iter->range = NULL;
594 
595 	mtrr_lookup_start(iter);
596 }
597 
598 static bool mtrr_lookup_okay(struct mtrr_iter *iter)
599 {
600 	if (iter->fixed) {
601 		iter->mem_type = iter->mtrr_state->fixed_ranges[iter->index];
602 		return true;
603 	}
604 
605 	if (iter->range) {
606 		iter->mem_type = iter->range->base & 0xff;
607 		return true;
608 	}
609 
610 	return false;
611 }
612 
613 static void mtrr_lookup_next(struct mtrr_iter *iter)
614 {
615 	if (iter->fixed)
616 		mtrr_lookup_fixed_next(iter);
617 	else
618 		mtrr_lookup_var_next(iter);
619 }
620 
621 #define mtrr_for_each_mem_type(_iter_, _mtrr_, _gpa_start_, _gpa_end_) \
622 	for (mtrr_lookup_init(_iter_, _mtrr_, _gpa_start_, _gpa_end_); \
623 	     mtrr_lookup_okay(_iter_); mtrr_lookup_next(_iter_))
624 
625 u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
626 {
627 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
628 	struct mtrr_iter iter;
629 	u64 start, end;
630 	int type = -1;
631 	const int wt_wb_mask = (1 << MTRR_TYPE_WRBACK)
632 			       | (1 << MTRR_TYPE_WRTHROUGH);
633 
634 	start = gfn_to_gpa(gfn);
635 	end = start + PAGE_SIZE;
636 
637 	mtrr_for_each_mem_type(&iter, mtrr_state, start, end) {
638 		int curr_type = iter.mem_type;
639 
640 		/*
641 		 * Please refer to Intel SDM Volume 3: 11.11.4.1 MTRR
642 		 * Precedences.
643 		 */
644 
645 		if (type == -1) {
646 			type = curr_type;
647 			continue;
648 		}
649 
650 		/*
651 		 * If two or more variable memory ranges match and the
652 		 * memory types are identical, then that memory type is
653 		 * used.
654 		 */
655 		if (type == curr_type)
656 			continue;
657 
658 		/*
659 		 * If two or more variable memory ranges match and one of
660 		 * the memory types is UC, the UC memory type used.
661 		 */
662 		if (curr_type == MTRR_TYPE_UNCACHABLE)
663 			return MTRR_TYPE_UNCACHABLE;
664 
665 		/*
666 		 * If two or more variable memory ranges match and the
667 		 * memory types are WT and WB, the WT memory type is used.
668 		 */
669 		if (((1 << type) & wt_wb_mask) &&
670 		      ((1 << curr_type) & wt_wb_mask)) {
671 			type = MTRR_TYPE_WRTHROUGH;
672 			continue;
673 		}
674 
675 		/*
676 		 * For overlaps not defined by the above rules, processor
677 		 * behavior is undefined.
678 		 */
679 
680 		/* We use WB for this undefined behavior. :( */
681 		return MTRR_TYPE_WRBACK;
682 	}
683 
684 	if (iter.mtrr_disabled)
685 		return mtrr_disabled_type(vcpu);
686 
687 	/* not contained in any MTRRs. */
688 	if (type == -1)
689 		return mtrr_default_type(mtrr_state);
690 
691 	/*
692 	 * We just check one page, partially covered by MTRRs is
693 	 * impossible.
694 	 */
695 	WARN_ON(iter.partial_map);
696 
697 	return type;
698 }
699 EXPORT_SYMBOL_GPL(kvm_mtrr_get_guest_memory_type);
700 
701 bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
702 					  int page_num)
703 {
704 	struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
705 	struct mtrr_iter iter;
706 	u64 start, end;
707 	int type = -1;
708 
709 	start = gfn_to_gpa(gfn);
710 	end = gfn_to_gpa(gfn + page_num);
711 	mtrr_for_each_mem_type(&iter, mtrr_state, start, end) {
712 		if (type == -1) {
713 			type = iter.mem_type;
714 			continue;
715 		}
716 
717 		if (type != iter.mem_type)
718 			return false;
719 	}
720 
721 	if (iter.mtrr_disabled)
722 		return true;
723 
724 	if (!iter.partial_map)
725 		return true;
726 
727 	if (type == -1)
728 		return true;
729 
730 	return type == mtrr_default_type(mtrr_state);
731 }
732