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1 /*
2  * Kernel-based Virtual Machine driver for Linux
3  * cpuid support routines
4  *
5  * derived from arch/x86/kvm/x86.c
6  *
7  * Copyright 2011 Red Hat, Inc. and/or its affiliates.
8  * Copyright IBM Corporation, 2008
9  *
10  * This work is licensed under the terms of the GNU GPL, version 2.  See
11  * the COPYING file in the top-level directory.
12  *
13  */
14 
15 #include <linux/kvm_host.h>
16 #include <linux/module.h>
17 #include <linux/vmalloc.h>
18 #include <linux/uaccess.h>
19 #include <asm/user.h>
20 #include <asm/xsave.h>
21 #include "cpuid.h"
22 #include "lapic.h"
23 #include "mmu.h"
24 #include "trace.h"
25 
kvm_update_cpuid(struct kvm_vcpu * vcpu)26 void kvm_update_cpuid(struct kvm_vcpu *vcpu)
27 {
28 	struct kvm_cpuid_entry2 *best;
29 	struct kvm_lapic *apic = vcpu->arch.apic;
30 
31 	best = kvm_find_cpuid_entry(vcpu, 1, 0);
32 	if (!best)
33 		return;
34 
35 	/* Update OSXSAVE bit */
36 	if (cpu_has_xsave && best->function == 0x1) {
37 		best->ecx &= ~(bit(X86_FEATURE_OSXSAVE));
38 		if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
39 			best->ecx |= bit(X86_FEATURE_OSXSAVE);
40 	}
41 
42 	if (apic) {
43 		if (best->ecx & bit(X86_FEATURE_TSC_DEADLINE_TIMER))
44 			apic->lapic_timer.timer_mode_mask = 3 << 17;
45 		else
46 			apic->lapic_timer.timer_mode_mask = 1 << 17;
47 	}
48 
49 	kvm_pmu_cpuid_update(vcpu);
50 }
51 
is_efer_nx(void)52 static int is_efer_nx(void)
53 {
54 	unsigned long long efer = 0;
55 
56 	rdmsrl_safe(MSR_EFER, &efer);
57 	return efer & EFER_NX;
58 }
59 
cpuid_fix_nx_cap(struct kvm_vcpu * vcpu)60 static void cpuid_fix_nx_cap(struct kvm_vcpu *vcpu)
61 {
62 	int i;
63 	struct kvm_cpuid_entry2 *e, *entry;
64 
65 	entry = NULL;
66 	for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
67 		e = &vcpu->arch.cpuid_entries[i];
68 		if (e->function == 0x80000001) {
69 			entry = e;
70 			break;
71 		}
72 	}
73 	if (entry && (entry->edx & (1 << 20)) && !is_efer_nx()) {
74 		entry->edx &= ~(1 << 20);
75 		printk(KERN_INFO "kvm: guest NX capability removed\n");
76 	}
77 }
78 
79 /* when an old userspace process fills a new kernel module */
kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu * vcpu,struct kvm_cpuid * cpuid,struct kvm_cpuid_entry __user * entries)80 int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
81 			     struct kvm_cpuid *cpuid,
82 			     struct kvm_cpuid_entry __user *entries)
83 {
84 	int r, i;
85 	struct kvm_cpuid_entry *cpuid_entries;
86 
87 	r = -E2BIG;
88 	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
89 		goto out;
90 	r = -ENOMEM;
91 	cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry) * cpuid->nent);
92 	if (!cpuid_entries)
93 		goto out;
94 	r = -EFAULT;
95 	if (copy_from_user(cpuid_entries, entries,
96 			   cpuid->nent * sizeof(struct kvm_cpuid_entry)))
97 		goto out_free;
98 	for (i = 0; i < cpuid->nent; i++) {
99 		vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function;
100 		vcpu->arch.cpuid_entries[i].eax = cpuid_entries[i].eax;
101 		vcpu->arch.cpuid_entries[i].ebx = cpuid_entries[i].ebx;
102 		vcpu->arch.cpuid_entries[i].ecx = cpuid_entries[i].ecx;
103 		vcpu->arch.cpuid_entries[i].edx = cpuid_entries[i].edx;
104 		vcpu->arch.cpuid_entries[i].index = 0;
105 		vcpu->arch.cpuid_entries[i].flags = 0;
106 		vcpu->arch.cpuid_entries[i].padding[0] = 0;
107 		vcpu->arch.cpuid_entries[i].padding[1] = 0;
108 		vcpu->arch.cpuid_entries[i].padding[2] = 0;
109 	}
110 	vcpu->arch.cpuid_nent = cpuid->nent;
111 	cpuid_fix_nx_cap(vcpu);
112 	r = 0;
113 	kvm_apic_set_version(vcpu);
114 	kvm_x86_ops->cpuid_update(vcpu);
115 	kvm_update_cpuid(vcpu);
116 
117 out_free:
118 	vfree(cpuid_entries);
119 out:
120 	return r;
121 }
122 
kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu * vcpu,struct kvm_cpuid2 * cpuid,struct kvm_cpuid_entry2 __user * entries)123 int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
124 			      struct kvm_cpuid2 *cpuid,
125 			      struct kvm_cpuid_entry2 __user *entries)
126 {
127 	int r;
128 
129 	r = -E2BIG;
130 	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
131 		goto out;
132 	r = -EFAULT;
133 	if (copy_from_user(&vcpu->arch.cpuid_entries, entries,
134 			   cpuid->nent * sizeof(struct kvm_cpuid_entry2)))
135 		goto out;
136 	vcpu->arch.cpuid_nent = cpuid->nent;
137 	kvm_apic_set_version(vcpu);
138 	kvm_x86_ops->cpuid_update(vcpu);
139 	kvm_update_cpuid(vcpu);
140 	return 0;
141 
142 out:
143 	return r;
144 }
145 
kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu * vcpu,struct kvm_cpuid2 * cpuid,struct kvm_cpuid_entry2 __user * entries)146 int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
147 			      struct kvm_cpuid2 *cpuid,
148 			      struct kvm_cpuid_entry2 __user *entries)
149 {
150 	int r;
151 
152 	r = -E2BIG;
153 	if (cpuid->nent < vcpu->arch.cpuid_nent)
154 		goto out;
155 	r = -EFAULT;
156 	if (copy_to_user(entries, &vcpu->arch.cpuid_entries,
157 			 vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2)))
158 		goto out;
159 	return 0;
160 
161 out:
162 	cpuid->nent = vcpu->arch.cpuid_nent;
163 	return r;
164 }
165 
cpuid_mask(u32 * word,int wordnum)166 static void cpuid_mask(u32 *word, int wordnum)
167 {
168 	*word &= boot_cpu_data.x86_capability[wordnum];
169 }
170 
do_cpuid_1_ent(struct kvm_cpuid_entry2 * entry,u32 function,u32 index)171 static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
172 			   u32 index)
173 {
174 	entry->function = function;
175 	entry->index = index;
176 	cpuid_count(entry->function, entry->index,
177 		    &entry->eax, &entry->ebx, &entry->ecx, &entry->edx);
178 	entry->flags = 0;
179 }
180 
supported_xcr0_bit(unsigned bit)181 static bool supported_xcr0_bit(unsigned bit)
182 {
183 	u64 mask = ((u64)1 << bit);
184 
185 	return mask & (XSTATE_FP | XSTATE_SSE | XSTATE_YMM) & host_xcr0;
186 }
187 
188 #define F(x) bit(X86_FEATURE_##x)
189 
do_cpuid_ent(struct kvm_cpuid_entry2 * entry,u32 function,u32 index,int * nent,int maxnent)190 static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
191 			 u32 index, int *nent, int maxnent)
192 {
193 	int r;
194 	unsigned f_nx = is_efer_nx() ? F(NX) : 0;
195 #ifdef CONFIG_X86_64
196 	unsigned f_gbpages = (kvm_x86_ops->get_lpage_level() == PT_PDPE_LEVEL)
197 				? F(GBPAGES) : 0;
198 	unsigned f_lm = F(LM);
199 #else
200 	unsigned f_gbpages = 0;
201 	unsigned f_lm = 0;
202 #endif
203 	unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;
204 
205 	/* cpuid 1.edx */
206 	const u32 kvm_supported_word0_x86_features =
207 		F(FPU) | F(VME) | F(DE) | F(PSE) |
208 		F(TSC) | F(MSR) | F(PAE) | F(MCE) |
209 		F(CX8) | F(APIC) | 0 /* Reserved */ | F(SEP) |
210 		F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
211 		F(PAT) | F(PSE36) | 0 /* PSN */ | F(CLFLSH) |
212 		0 /* Reserved, DS, ACPI */ | F(MMX) |
213 		F(FXSR) | F(XMM) | F(XMM2) | F(SELFSNOOP) |
214 		0 /* HTT, TM, Reserved, PBE */;
215 	/* cpuid 0x80000001.edx */
216 	const u32 kvm_supported_word1_x86_features =
217 		F(FPU) | F(VME) | F(DE) | F(PSE) |
218 		F(TSC) | F(MSR) | F(PAE) | F(MCE) |
219 		F(CX8) | F(APIC) | 0 /* Reserved */ | F(SYSCALL) |
220 		F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
221 		F(PAT) | F(PSE36) | 0 /* Reserved */ |
222 		f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
223 		F(FXSR) | F(FXSR_OPT) | f_gbpages | f_rdtscp |
224 		0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
225 	/* cpuid 1.ecx */
226 	const u32 kvm_supported_word4_x86_features =
227 		F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ |
228 		0 /* DS-CPL, VMX, SMX, EST */ |
229 		0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ |
230 		F(FMA) | F(CX16) | 0 /* xTPR Update, PDCM */ |
231 		0 /* Reserved, DCA */ | F(XMM4_1) |
232 		F(XMM4_2) | F(X2APIC) | F(MOVBE) | F(POPCNT) |
233 		0 /* Reserved*/ | F(AES) | F(XSAVE) | 0 /* OSXSAVE */ | F(AVX) |
234 		F(F16C) | F(RDRAND);
235 	/* cpuid 0x80000001.ecx */
236 	const u32 kvm_supported_word6_x86_features =
237 		F(LAHF_LM) | F(CMP_LEGACY) | 0 /*SVM*/ | 0 /* ExtApicSpace */ |
238 		F(CR8_LEGACY) | F(ABM) | F(SSE4A) | F(MISALIGNSSE) |
239 		F(3DNOWPREFETCH) | F(OSVW) | 0 /* IBS */ | F(XOP) |
240 		0 /* SKINIT, WDT, LWP */ | F(FMA4) | F(TBM);
241 
242 	/* cpuid 0xC0000001.edx */
243 	const u32 kvm_supported_word5_x86_features =
244 		F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |
245 		F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) |
246 		F(PMM) | F(PMM_EN);
247 
248 	/* cpuid 7.0.ebx */
249 	const u32 kvm_supported_word9_x86_features =
250 		F(FSGSBASE) | F(BMI1) | F(AVX2) | F(SMEP) | F(BMI2) | F(ERMS);
251 
252 	/* all calls to cpuid_count() should be made on the same cpu */
253 	get_cpu();
254 
255 	r = -E2BIG;
256 
257 	if (*nent >= maxnent)
258 		goto out;
259 
260 	do_cpuid_1_ent(entry, function, index);
261 	++*nent;
262 
263 	switch (function) {
264 	case 0:
265 		entry->eax = min(entry->eax, (u32)0xd);
266 		break;
267 	case 1:
268 		entry->edx &= kvm_supported_word0_x86_features;
269 		cpuid_mask(&entry->edx, 0);
270 		entry->ecx &= kvm_supported_word4_x86_features;
271 		cpuid_mask(&entry->ecx, 4);
272 		/* we support x2apic emulation even if host does not support
273 		 * it since we emulate x2apic in software */
274 		entry->ecx |= F(X2APIC);
275 		break;
276 	/* function 2 entries are STATEFUL. That is, repeated cpuid commands
277 	 * may return different values. This forces us to get_cpu() before
278 	 * issuing the first command, and also to emulate this annoying behavior
279 	 * in kvm_emulate_cpuid() using KVM_CPUID_FLAG_STATE_READ_NEXT */
280 	case 2: {
281 		int t, times = entry->eax & 0xff;
282 
283 		entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
284 		entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
285 		for (t = 1; t < times; ++t) {
286 			if (*nent >= maxnent)
287 				goto out;
288 
289 			do_cpuid_1_ent(&entry[t], function, 0);
290 			entry[t].flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
291 			++*nent;
292 		}
293 		break;
294 	}
295 	/* function 4 has additional index. */
296 	case 4: {
297 		int i, cache_type;
298 
299 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
300 		/* read more entries until cache_type is zero */
301 		for (i = 1; ; ++i) {
302 			if (*nent >= maxnent)
303 				goto out;
304 
305 			cache_type = entry[i - 1].eax & 0x1f;
306 			if (!cache_type)
307 				break;
308 			do_cpuid_1_ent(&entry[i], function, i);
309 			entry[i].flags |=
310 			       KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
311 			++*nent;
312 		}
313 		break;
314 	}
315 	case 7: {
316 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
317 		/* Mask ebx against host capbability word 9 */
318 		if (index == 0) {
319 			entry->ebx &= kvm_supported_word9_x86_features;
320 			cpuid_mask(&entry->ebx, 9);
321 		} else
322 			entry->ebx = 0;
323 		entry->eax = 0;
324 		entry->ecx = 0;
325 		entry->edx = 0;
326 		break;
327 	}
328 	case 9:
329 		break;
330 	case 0xa: { /* Architectural Performance Monitoring */
331 		struct x86_pmu_capability cap;
332 		union cpuid10_eax eax;
333 		union cpuid10_edx edx;
334 
335 		perf_get_x86_pmu_capability(&cap);
336 
337 		/*
338 		 * Only support guest architectural pmu on a host
339 		 * with architectural pmu.
340 		 */
341 		if (!cap.version)
342 			memset(&cap, 0, sizeof(cap));
343 
344 		eax.split.version_id = min(cap.version, 2);
345 		eax.split.num_counters = cap.num_counters_gp;
346 		eax.split.bit_width = cap.bit_width_gp;
347 		eax.split.mask_length = cap.events_mask_len;
348 
349 		edx.split.num_counters_fixed = cap.num_counters_fixed;
350 		edx.split.bit_width_fixed = cap.bit_width_fixed;
351 		edx.split.reserved = 0;
352 
353 		entry->eax = eax.full;
354 		entry->ebx = cap.events_mask;
355 		entry->ecx = 0;
356 		entry->edx = edx.full;
357 		break;
358 	}
359 	/* function 0xb has additional index. */
360 	case 0xb: {
361 		int i, level_type;
362 
363 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
364 		/* read more entries until level_type is zero */
365 		for (i = 1; ; ++i) {
366 			if (*nent >= maxnent)
367 				goto out;
368 
369 			level_type = entry[i - 1].ecx & 0xff00;
370 			if (!level_type)
371 				break;
372 			do_cpuid_1_ent(&entry[i], function, i);
373 			entry[i].flags |=
374 			       KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
375 			++*nent;
376 		}
377 		break;
378 	}
379 	case 0xd: {
380 		int idx, i;
381 
382 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
383 		for (idx = 1, i = 1; idx < 64; ++idx) {
384 			if (*nent >= maxnent)
385 				goto out;
386 
387 			do_cpuid_1_ent(&entry[i], function, idx);
388 			if (entry[i].eax == 0 || !supported_xcr0_bit(idx))
389 				continue;
390 			entry[i].flags |=
391 			       KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
392 			++*nent;
393 			++i;
394 		}
395 		break;
396 	}
397 	case KVM_CPUID_SIGNATURE: {
398 		char signature[12] = "KVMKVMKVM\0\0";
399 		u32 *sigptr = (u32 *)signature;
400 		entry->eax = 0;
401 		entry->ebx = sigptr[0];
402 		entry->ecx = sigptr[1];
403 		entry->edx = sigptr[2];
404 		break;
405 	}
406 	case KVM_CPUID_FEATURES:
407 		entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
408 			     (1 << KVM_FEATURE_NOP_IO_DELAY) |
409 			     (1 << KVM_FEATURE_CLOCKSOURCE2) |
410 			     (1 << KVM_FEATURE_ASYNC_PF) |
411 			     (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
412 
413 		if (sched_info_on())
414 			entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
415 
416 		entry->ebx = 0;
417 		entry->ecx = 0;
418 		entry->edx = 0;
419 		break;
420 	case 0x80000000:
421 		entry->eax = min(entry->eax, 0x8000001a);
422 		break;
423 	case 0x80000001:
424 		entry->edx &= kvm_supported_word1_x86_features;
425 		cpuid_mask(&entry->edx, 1);
426 		entry->ecx &= kvm_supported_word6_x86_features;
427 		cpuid_mask(&entry->ecx, 6);
428 		break;
429 	case 0x80000008: {
430 		unsigned g_phys_as = (entry->eax >> 16) & 0xff;
431 		unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U);
432 		unsigned phys_as = entry->eax & 0xff;
433 
434 		if (!g_phys_as)
435 			g_phys_as = phys_as;
436 		entry->eax = g_phys_as | (virt_as << 8);
437 		entry->ebx = entry->edx = 0;
438 		break;
439 	}
440 	case 0x80000019:
441 		entry->ecx = entry->edx = 0;
442 		break;
443 	case 0x8000001a:
444 		break;
445 	case 0x8000001d:
446 		break;
447 	/*Add support for Centaur's CPUID instruction*/
448 	case 0xC0000000:
449 		/*Just support up to 0xC0000004 now*/
450 		entry->eax = min(entry->eax, 0xC0000004);
451 		break;
452 	case 0xC0000001:
453 		entry->edx &= kvm_supported_word5_x86_features;
454 		cpuid_mask(&entry->edx, 5);
455 		break;
456 	case 3: /* Processor serial number */
457 	case 5: /* MONITOR/MWAIT */
458 	case 6: /* Thermal management */
459 	case 0x80000007: /* Advanced power management */
460 	case 0xC0000002:
461 	case 0xC0000003:
462 	case 0xC0000004:
463 	default:
464 		entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
465 		break;
466 	}
467 
468 	kvm_x86_ops->set_supported_cpuid(function, entry);
469 
470 	r = 0;
471 
472 out:
473 	put_cpu();
474 
475 	return r;
476 }
477 
478 #undef F
479 
480 struct kvm_cpuid_param {
481 	u32 func;
482 	u32 idx;
483 	bool has_leaf_count;
484 	bool (*qualifier)(struct kvm_cpuid_param *param);
485 };
486 
is_centaur_cpu(struct kvm_cpuid_param * param)487 static bool is_centaur_cpu(struct kvm_cpuid_param *param)
488 {
489 	return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
490 }
491 
kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 * cpuid,struct kvm_cpuid_entry2 __user * entries)492 int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
493 				      struct kvm_cpuid_entry2 __user *entries)
494 {
495 	struct kvm_cpuid_entry2 *cpuid_entries;
496 	int limit, nent = 0, r = -E2BIG, i;
497 	u32 func;
498 	static struct kvm_cpuid_param param[] = {
499 		{ .func = 0, .has_leaf_count = true },
500 		{ .func = 0x80000000, .has_leaf_count = true },
501 		{ .func = 0xC0000000, .qualifier = is_centaur_cpu, .has_leaf_count = true },
502 		{ .func = KVM_CPUID_SIGNATURE },
503 		{ .func = KVM_CPUID_FEATURES },
504 	};
505 
506 	if (cpuid->nent < 1)
507 		goto out;
508 	if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
509 		cpuid->nent = KVM_MAX_CPUID_ENTRIES;
510 	r = -ENOMEM;
511 	cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry2) * cpuid->nent);
512 	if (!cpuid_entries)
513 		goto out;
514 
515 	r = 0;
516 	for (i = 0; i < ARRAY_SIZE(param); i++) {
517 		struct kvm_cpuid_param *ent = &param[i];
518 
519 		if (ent->qualifier && !ent->qualifier(ent))
520 			continue;
521 
522 		r = do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
523 				&nent, cpuid->nent);
524 
525 		if (r)
526 			goto out_free;
527 
528 		if (!ent->has_leaf_count)
529 			continue;
530 
531 		limit = cpuid_entries[nent - 1].eax;
532 		for (func = ent->func + 1; func <= limit && nent < cpuid->nent && r == 0; ++func)
533 			r = do_cpuid_ent(&cpuid_entries[nent], func, ent->idx,
534 				     &nent, cpuid->nent);
535 
536 		if (r)
537 			goto out_free;
538 	}
539 
540 	r = -EFAULT;
541 	if (copy_to_user(entries, cpuid_entries,
542 			 nent * sizeof(struct kvm_cpuid_entry2)))
543 		goto out_free;
544 	cpuid->nent = nent;
545 	r = 0;
546 
547 out_free:
548 	vfree(cpuid_entries);
549 out:
550 	return r;
551 }
552 
move_to_next_stateful_cpuid_entry(struct kvm_vcpu * vcpu,int i)553 static int move_to_next_stateful_cpuid_entry(struct kvm_vcpu *vcpu, int i)
554 {
555 	struct kvm_cpuid_entry2 *e = &vcpu->arch.cpuid_entries[i];
556 	int j, nent = vcpu->arch.cpuid_nent;
557 
558 	e->flags &= ~KVM_CPUID_FLAG_STATE_READ_NEXT;
559 	/* when no next entry is found, the current entry[i] is reselected */
560 	for (j = i + 1; ; j = (j + 1) % nent) {
561 		struct kvm_cpuid_entry2 *ej = &vcpu->arch.cpuid_entries[j];
562 		if (ej->function == e->function) {
563 			ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
564 			return j;
565 		}
566 	}
567 	return 0; /* silence gcc, even though control never reaches here */
568 }
569 
570 /* find an entry with matching function, matching index (if needed), and that
571  * should be read next (if it's stateful) */
is_matching_cpuid_entry(struct kvm_cpuid_entry2 * e,u32 function,u32 index)572 static int is_matching_cpuid_entry(struct kvm_cpuid_entry2 *e,
573 	u32 function, u32 index)
574 {
575 	if (e->function != function)
576 		return 0;
577 	if ((e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) && e->index != index)
578 		return 0;
579 	if ((e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC) &&
580 	    !(e->flags & KVM_CPUID_FLAG_STATE_READ_NEXT))
581 		return 0;
582 	return 1;
583 }
584 
kvm_find_cpuid_entry(struct kvm_vcpu * vcpu,u32 function,u32 index)585 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
586 					      u32 function, u32 index)
587 {
588 	int i;
589 	struct kvm_cpuid_entry2 *best = NULL;
590 
591 	for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
592 		struct kvm_cpuid_entry2 *e;
593 
594 		e = &vcpu->arch.cpuid_entries[i];
595 		if (is_matching_cpuid_entry(e, function, index)) {
596 			if (e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC)
597 				move_to_next_stateful_cpuid_entry(vcpu, i);
598 			best = e;
599 			break;
600 		}
601 	}
602 	return best;
603 }
604 EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
605 
cpuid_maxphyaddr(struct kvm_vcpu * vcpu)606 int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
607 {
608 	struct kvm_cpuid_entry2 *best;
609 
610 	best = kvm_find_cpuid_entry(vcpu, 0x80000000, 0);
611 	if (!best || best->eax < 0x80000008)
612 		goto not_found;
613 	best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
614 	if (best)
615 		return best->eax & 0xff;
616 not_found:
617 	return 36;
618 }
619 
620 /*
621  * If no match is found, check whether we exceed the vCPU's limit
622  * and return the content of the highest valid _standard_ leaf instead.
623  * This is to satisfy the CPUID specification.
624  */
check_cpuid_limit(struct kvm_vcpu * vcpu,u32 function,u32 index)625 static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
626                                                   u32 function, u32 index)
627 {
628 	struct kvm_cpuid_entry2 *maxlevel;
629 
630 	maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
631 	if (!maxlevel || maxlevel->eax >= function)
632 		return NULL;
633 	if (function & 0x80000000) {
634 		maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
635 		if (!maxlevel)
636 			return NULL;
637 	}
638 	return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
639 }
640 
kvm_emulate_cpuid(struct kvm_vcpu * vcpu)641 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
642 {
643 	u32 function, index;
644 	struct kvm_cpuid_entry2 *best;
645 
646 	function = kvm_register_read(vcpu, VCPU_REGS_RAX);
647 	index = kvm_register_read(vcpu, VCPU_REGS_RCX);
648 	kvm_register_write(vcpu, VCPU_REGS_RAX, 0);
649 	kvm_register_write(vcpu, VCPU_REGS_RBX, 0);
650 	kvm_register_write(vcpu, VCPU_REGS_RCX, 0);
651 	kvm_register_write(vcpu, VCPU_REGS_RDX, 0);
652 	best = kvm_find_cpuid_entry(vcpu, function, index);
653 
654 	if (!best)
655 		best = check_cpuid_limit(vcpu, function, index);
656 
657 	if (best) {
658 		kvm_register_write(vcpu, VCPU_REGS_RAX, best->eax);
659 		kvm_register_write(vcpu, VCPU_REGS_RBX, best->ebx);
660 		kvm_register_write(vcpu, VCPU_REGS_RCX, best->ecx);
661 		kvm_register_write(vcpu, VCPU_REGS_RDX, best->edx);
662 	}
663 	kvm_x86_ops->skip_emulated_instruction(vcpu);
664 	trace_kvm_cpuid(function,
665 			kvm_register_read(vcpu, VCPU_REGS_RAX),
666 			kvm_register_read(vcpu, VCPU_REGS_RBX),
667 			kvm_register_read(vcpu, VCPU_REGS_RCX),
668 			kvm_register_read(vcpu, VCPU_REGS_RDX));
669 }
670 EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);
671