1 #include <linux/export.h>
2 #include <linux/init.h>
3 #include <linux/bitops.h>
8 #include <linux/sched.h>
9 #include <asm/processor.h>
12 #include <asm/pci-direct.h>
15 # include <asm/mmconfig.h>
16 # include <asm/cacheflush.h>
21 static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
23 struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
27 WARN_ONCE((c->x86 != 0xf), "%s should only be used on K8!\n", __func__);
32 err = rdmsr_safe_regs(gprs);
34 *p = gprs[0] | ((u64)gprs[2] << 32);
39 static inline int wrmsrl_amd_safe(unsigned msr, unsigned long long val)
41 struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
44 WARN_ONCE((c->x86 != 0xf), "%s should only be used on K8!\n", __func__);
51 return wrmsr_safe_regs(gprs);
56 * B step AMD K6 before B 9730xxxx have hardware bugs that can cause
57 * misexecution of code under Linux. Owners of such processors should
58 * contact AMD for precise details and a CPU swap.
60 * See http://www.multimania.com/poulot/k6bug.html
61 * and section 2.6.2 of "AMD-K6 Processor Revision Guide - Model 6"
62 * (Publication # 21266 Issue Date: August 1998)
64 * The following test is erm.. interesting. AMD neglected to up
65 * the chip setting when fixing the bug but they also tweaked some
66 * performance at the same time..
69 extern void vide(void);
70 __asm__(".align 4\nvide: ret");
72 static void __cpuinit init_amd_k5(struct cpuinfo_x86 *c)
75 * General Systems BIOSen alias the cpu frequency registers
76 * of the Elan at 0x000df000. Unfortuantly, one of the Linux
77 * drivers subsequently pokes it, and changes the CPU speed.
78 * Workaround : Remove the unneeded alias.
80 #define CBAR (0xfffc) /* Configuration Base Address (32-bit) */
81 #define CBAR_ENB (0x80000000)
82 #define CBAR_KEY (0X000000CB)
83 if (c->x86_model == 9 || c->x86_model == 10) {
84 if (inl(CBAR) & CBAR_ENB)
85 outl(0 | CBAR_KEY, CBAR);
90 static void __cpuinit init_amd_k6(struct cpuinfo_x86 *c)
93 int mbytes = num_physpages >> (20-PAGE_SHIFT);
95 if (c->x86_model < 6) {
96 /* Based on AMD doc 20734R - June 2000 */
97 if (c->x86_model == 0) {
98 clear_cpu_cap(c, X86_FEATURE_APIC);
99 set_cpu_cap(c, X86_FEATURE_PGE);
104 if (c->x86_model == 6 && c->x86_mask == 1) {
105 const int K6_BUG_LOOP = 1000000;
107 void (*f_vide)(void);
110 printk(KERN_INFO "AMD K6 stepping B detected - ");
113 * It looks like AMD fixed the 2.6.2 bug and improved indirect
114 * calls at the same time.
125 if (d > 20*K6_BUG_LOOP)
127 "system stability may be impaired when more than 32 MB are used.\n");
129 printk(KERN_CONT "probably OK (after B9730xxxx).\n");
132 /* K6 with old style WHCR */
133 if (c->x86_model < 8 ||
134 (c->x86_model == 8 && c->x86_mask < 8)) {
135 /* We can only write allocate on the low 508Mb */
139 rdmsr(MSR_K6_WHCR, l, h);
140 if ((l&0x0000FFFF) == 0) {
142 l = (1<<0)|((mbytes/4)<<1);
143 local_irq_save(flags);
145 wrmsr(MSR_K6_WHCR, l, h);
146 local_irq_restore(flags);
147 printk(KERN_INFO "Enabling old style K6 write allocation for %d Mb\n",
153 if ((c->x86_model == 8 && c->x86_mask > 7) ||
154 c->x86_model == 9 || c->x86_model == 13) {
155 /* The more serious chips .. */
160 rdmsr(MSR_K6_WHCR, l, h);
161 if ((l&0xFFFF0000) == 0) {
163 l = ((mbytes>>2)<<22)|(1<<16);
164 local_irq_save(flags);
166 wrmsr(MSR_K6_WHCR, l, h);
167 local_irq_restore(flags);
168 printk(KERN_INFO "Enabling new style K6 write allocation for %d Mb\n",
175 if (c->x86_model == 10) {
176 /* AMD Geode LX is model 10 */
177 /* placeholder for any needed mods */
182 static void __cpuinit amd_k7_smp_check(struct cpuinfo_x86 *c)
184 /* calling is from identify_secondary_cpu() ? */
189 * Certain Athlons might work (for various values of 'work') in SMP
190 * but they are not certified as MP capable.
192 /* Athlon 660/661 is valid. */
193 if ((c->x86_model == 6) && ((c->x86_mask == 0) ||
197 /* Duron 670 is valid */
198 if ((c->x86_model == 7) && (c->x86_mask == 0))
202 * Athlon 662, Duron 671, and Athlon >model 7 have capability
203 * bit. It's worth noting that the A5 stepping (662) of some
204 * Athlon XP's have the MP bit set.
205 * See http://www.heise.de/newsticker/data/jow-18.10.01-000 for
208 if (((c->x86_model == 6) && (c->x86_mask >= 2)) ||
209 ((c->x86_model == 7) && (c->x86_mask >= 1)) ||
214 /* If we get here, not a certified SMP capable AMD system. */
217 * Don't taint if we are running SMP kernel on a single non-MP
220 WARN_ONCE(1, "WARNING: This combination of AMD"
221 " processors is not suitable for SMP.\n");
222 if (!test_taint(TAINT_UNSAFE_SMP))
223 add_taint(TAINT_UNSAFE_SMP);
229 static void __cpuinit init_amd_k7(struct cpuinfo_x86 *c)
234 * Bit 15 of Athlon specific MSR 15, needs to be 0
235 * to enable SSE on Palomino/Morgan/Barton CPU's.
236 * If the BIOS didn't enable it already, enable it here.
238 if (c->x86_model >= 6 && c->x86_model <= 10) {
239 if (!cpu_has(c, X86_FEATURE_XMM)) {
240 printk(KERN_INFO "Enabling disabled K7/SSE Support.\n");
241 rdmsr(MSR_K7_HWCR, l, h);
243 wrmsr(MSR_K7_HWCR, l, h);
244 set_cpu_cap(c, X86_FEATURE_XMM);
249 * It's been determined by AMD that Athlons since model 8 stepping 1
250 * are more robust with CLK_CTL set to 200xxxxx instead of 600xxxxx
251 * As per AMD technical note 27212 0.2
253 if ((c->x86_model == 8 && c->x86_mask >= 1) || (c->x86_model > 8)) {
254 rdmsr(MSR_K7_CLK_CTL, l, h);
255 if ((l & 0xfff00000) != 0x20000000) {
257 "CPU: CLK_CTL MSR was %x. Reprogramming to %x\n",
258 l, ((l & 0x000fffff)|0x20000000));
259 wrmsr(MSR_K7_CLK_CTL, (l & 0x000fffff)|0x20000000, h);
263 set_cpu_cap(c, X86_FEATURE_K7);
271 * To workaround broken NUMA config. Read the comment in
272 * srat_detect_node().
274 static int __cpuinit nearby_node(int apicid)
278 for (i = apicid - 1; i >= 0; i--) {
279 node = __apicid_to_node[i];
280 if (node != NUMA_NO_NODE && node_online(node))
283 for (i = apicid + 1; i < MAX_LOCAL_APIC; i++) {
284 node = __apicid_to_node[i];
285 if (node != NUMA_NO_NODE && node_online(node))
288 return first_node(node_online_map); /* Shouldn't happen */
293 * Fixup core topology information for
294 * (1) AMD multi-node processors
295 * Assumption: Number of cores in each internal node is the same.
296 * (2) AMD processors supporting compute units
299 static void __cpuinit amd_get_topology(struct cpuinfo_x86 *c)
301 u32 nodes, cores_per_cu = 1;
303 int cpu = smp_processor_id();
305 /* get information required for multi-node processors */
306 if (cpu_has_topoext) {
307 u32 eax, ebx, ecx, edx;
309 cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
310 nodes = ((ecx >> 8) & 7) + 1;
313 /* get compute unit information */
314 smp_num_siblings = ((ebx >> 8) & 3) + 1;
315 c->compute_unit_id = ebx & 0xff;
316 cores_per_cu += ((ebx >> 8) & 3);
317 } else if (cpu_has(c, X86_FEATURE_NODEID_MSR)) {
320 rdmsrl(MSR_FAM10H_NODE_ID, value);
321 nodes = ((value >> 3) & 7) + 1;
326 /* fixup multi-node processor information */
331 set_cpu_cap(c, X86_FEATURE_AMD_DCM);
332 cores_per_node = c->x86_max_cores / nodes;
333 cus_per_node = cores_per_node / cores_per_cu;
335 /* store NodeID, use llc_shared_map to store sibling info */
336 per_cpu(cpu_llc_id, cpu) = node_id;
338 /* core id has to be in the [0 .. cores_per_node - 1] range */
339 c->cpu_core_id %= cores_per_node;
340 c->compute_unit_id %= cus_per_node;
346 * On a AMD dual core setup the lower bits of the APIC id distingush the cores.
347 * Assumes number of cores is a power of two.
349 static void __cpuinit amd_detect_cmp(struct cpuinfo_x86 *c)
353 int cpu = smp_processor_id();
355 bits = c->x86_coreid_bits;
356 /* Low order bits define the core id (index of core in socket) */
357 c->cpu_core_id = c->initial_apicid & ((1 << bits)-1);
358 /* Convert the initial APIC ID into the socket ID */
359 c->phys_proc_id = c->initial_apicid >> bits;
360 /* use socket ID also for last level cache */
361 per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
366 u16 amd_get_nb_id(int cpu)
370 id = per_cpu(cpu_llc_id, cpu);
374 EXPORT_SYMBOL_GPL(amd_get_nb_id);
376 static void __cpuinit srat_detect_node(struct cpuinfo_x86 *c)
379 int cpu = smp_processor_id();
381 unsigned apicid = c->apicid;
383 node = numa_cpu_node(cpu);
384 if (node == NUMA_NO_NODE)
385 node = per_cpu(cpu_llc_id, cpu);
388 * On multi-fabric platform (e.g. Numascale NumaChip) a
389 * platform-specific handler needs to be called to fixup some
392 if (x86_cpuinit.fixup_cpu_id)
393 x86_cpuinit.fixup_cpu_id(c, node);
395 if (!node_online(node)) {
397 * Two possibilities here:
399 * - The CPU is missing memory and no node was created. In
400 * that case try picking one from a nearby CPU.
402 * - The APIC IDs differ from the HyperTransport node IDs
403 * which the K8 northbridge parsing fills in. Assume
404 * they are all increased by a constant offset, but in
405 * the same order as the HT nodeids. If that doesn't
406 * result in a usable node fall back to the path for the
409 * This workaround operates directly on the mapping between
410 * APIC ID and NUMA node, assuming certain relationship
411 * between APIC ID, HT node ID and NUMA topology. As going
412 * through CPU mapping may alter the outcome, directly
413 * access __apicid_to_node[].
415 int ht_nodeid = c->initial_apicid;
417 if (ht_nodeid >= 0 &&
418 __apicid_to_node[ht_nodeid] != NUMA_NO_NODE)
419 node = __apicid_to_node[ht_nodeid];
420 /* Pick a nearby node */
421 if (!node_online(node))
422 node = nearby_node(apicid);
424 numa_set_node(cpu, node);
428 static void __cpuinit early_init_amd_mc(struct cpuinfo_x86 *c)
433 /* Multi core CPU? */
434 if (c->extended_cpuid_level < 0x80000008)
437 ecx = cpuid_ecx(0x80000008);
439 c->x86_max_cores = (ecx & 0xff) + 1;
441 /* CPU telling us the core id bits shift? */
442 bits = (ecx >> 12) & 0xF;
444 /* Otherwise recompute */
446 while ((1 << bits) < c->x86_max_cores)
450 c->x86_coreid_bits = bits;
454 static void __cpuinit bsp_init_amd(struct cpuinfo_x86 *c)
456 if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) {
459 (c->x86 == 0x10 && c->x86_model >= 0x2)) {
462 rdmsrl(MSR_K7_HWCR, val);
463 if (!(val & BIT(24)))
464 printk(KERN_WARNING FW_BUG "TSC doesn't count "
465 "with P0 frequency!\n");
469 if (c->x86 == 0x15) {
470 unsigned long upperbit;
473 cpuid = cpuid_edx(0x80000005);
474 assoc = cpuid >> 16 & 0xff;
475 upperbit = ((cpuid >> 24) << 10) / assoc;
477 va_align.mask = (upperbit - 1) & PAGE_MASK;
478 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
482 static void __cpuinit early_init_amd(struct cpuinfo_x86 *c)
484 early_init_amd_mc(c);
487 * c->x86_power is 8000_0007 edx. Bit 8 is TSC runs at constant rate
488 * with P/T states and does not stop in deep C-states
490 if (c->x86_power & (1 << 8)) {
491 set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
492 set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
493 if (!check_tsc_unstable())
494 sched_clock_stable = 1;
498 set_cpu_cap(c, X86_FEATURE_SYSCALL32);
500 /* Set MTRR capability flag if appropriate */
502 if (c->x86_model == 13 || c->x86_model == 9 ||
503 (c->x86_model == 8 && c->x86_mask >= 8))
504 set_cpu_cap(c, X86_FEATURE_K6_MTRR);
506 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PCI)
507 /* check CPU config space for extended APIC ID */
508 if (cpu_has_apic && c->x86 >= 0xf) {
510 val = read_pci_config(0, 24, 0, 0x68);
511 if ((val & ((1 << 17) | (1 << 18))) == ((1 << 17) | (1 << 18)))
512 set_cpu_cap(c, X86_FEATURE_EXTD_APICID);
517 static void __cpuinit init_amd(struct cpuinfo_x86 *c)
520 unsigned long long value;
524 * Disable TLB flush filter by setting HWCR.FFDIS on K8
525 * bit 6 of msr C001_0015
527 * Errata 63 for SH-B3 steppings
528 * Errata 122 for all steppings (F+ have it disabled by default)
531 rdmsrl(MSR_K7_HWCR, value);
533 wrmsrl(MSR_K7_HWCR, value);
540 * Bit 31 in normal CPUID used for nonstandard 3DNow ID;
541 * 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway
543 clear_cpu_cap(c, 0*32+31);
546 /* On C+ stepping K8 rep microcode works well for copy/memset */
550 level = cpuid_eax(1);
551 if ((level >= 0x0f48 && level < 0x0f50) || level >= 0x0f58)
552 set_cpu_cap(c, X86_FEATURE_REP_GOOD);
555 * Some BIOSes incorrectly force this feature, but only K8
556 * revision D (model = 0x14) and later actually support it.
557 * (AMD Erratum #110, docId: 25759).
559 if (c->x86_model < 0x14 && cpu_has(c, X86_FEATURE_LAHF_LM)) {
560 clear_cpu_cap(c, X86_FEATURE_LAHF_LM);
561 if (!rdmsrl_amd_safe(0xc001100d, &value)) {
562 value &= ~(1ULL << 32);
563 wrmsrl_amd_safe(0xc001100d, value);
569 set_cpu_cap(c, X86_FEATURE_REP_GOOD);
571 /* get apicid instead of initial apic id from cpuid */
572 c->apicid = hard_smp_processor_id();
576 * FIXME: We should handle the K5 here. Set up the write
577 * range and also turn on MSR 83 bits 4 and 31 (write alloc,
588 case 6: /* An Athlon/Duron */
593 /* K6s reports MCEs but don't actually have all the MSRs */
595 clear_cpu_cap(c, X86_FEATURE_MCE);
598 /* Enable workaround for FXSAVE leak */
600 set_cpu_cap(c, X86_FEATURE_FXSAVE_LEAK);
602 if (!c->x86_model_id[0]) {
605 /* Should distinguish Models here, but this is only
606 a fallback anyways. */
607 strcpy(c->x86_model_id, "Hammer");
612 /* re-enable TopologyExtensions if switched off by BIOS */
613 if ((c->x86 == 0x15) &&
614 (c->x86_model >= 0x10) && (c->x86_model <= 0x1f) &&
615 !cpu_has(c, X86_FEATURE_TOPOEXT)) {
617 if (!rdmsrl_safe(0xc0011005, &value)) {
619 wrmsrl_safe(0xc0011005, value);
620 rdmsrl(0xc0011005, value);
621 if (value & (1ULL << 54)) {
622 set_cpu_cap(c, X86_FEATURE_TOPOEXT);
623 printk(KERN_INFO FW_INFO "CPU: Re-enabling "
624 "disabled Topology Extensions Support\n");
630 * The way access filter has a performance penalty on some workloads.
631 * Disable it on the affected CPUs.
633 if ((c->x86 == 0x15) &&
634 (c->x86_model >= 0x02) && (c->x86_model < 0x20)) {
636 if (!rdmsrl_safe(0xc0011021, &value) && !(value & 0x1E)) {
638 wrmsrl_safe(0xc0011021, value);
642 cpu_detect_cache_sizes(c);
644 /* Multi core CPU? */
645 if (c->extended_cpuid_level >= 0x80000008) {
654 init_amd_cacheinfo(c);
657 set_cpu_cap(c, X86_FEATURE_K8);
660 /* MFENCE stops RDTSC speculation */
661 set_cpu_cap(c, X86_FEATURE_MFENCE_RDTSC);
665 if (c->x86 == 0x10) {
666 /* do this for boot cpu */
667 if (c == &boot_cpu_data)
668 check_enable_amd_mmconf_dmi();
670 fam10h_check_enable_mmcfg();
673 if (c == &boot_cpu_data && c->x86 >= 0xf) {
674 unsigned long long tseg;
677 * Split up direct mapping around the TSEG SMM area.
678 * Don't do it for gbpages because there seems very little
679 * benefit in doing so.
681 if (!rdmsrl_safe(MSR_K8_TSEG_ADDR, &tseg)) {
682 unsigned long pfn = tseg >> PAGE_SHIFT;
684 printk(KERN_DEBUG "tseg: %010llx\n", tseg);
685 if (pfn_range_is_mapped(pfn, pfn + 1))
686 set_memory_4k((unsigned long)__va(tseg), 1);
692 * Family 0x12 and above processors have APIC timer
693 * running in deep C states.
696 set_cpu_cap(c, X86_FEATURE_ARAT);
698 if (c->x86 == 0x10) {
700 * Disable GART TLB Walk Errors on Fam10h. We do this here
701 * because this is always needed when GART is enabled, even in a
702 * kernel which has no MCE support built in.
703 * BIOS should disable GartTlbWlk Errors themself. If
704 * it doesn't do it here as suggested by the BKDG.
706 * Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=33012
711 err = rdmsrl_safe(MSR_AMD64_MCx_MASK(4), &mask);
714 wrmsrl_safe(MSR_AMD64_MCx_MASK(4), mask);
718 * On family 10h BIOS may not have properly enabled WC+ support,
719 * causing it to be converted to CD memtype. This may result in
720 * performance degradation for certain nested-paging guests.
721 * Prevent this conversion by clearing bit 24 in
724 * NOTE: we want to use the _safe accessors so as not to #GP kvm
725 * guests on older kvm hosts.
728 rdmsrl_safe(MSR_AMD64_BU_CFG2, &value);
729 value &= ~(1ULL << 24);
730 wrmsrl_safe(MSR_AMD64_BU_CFG2, value);
733 rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy);
737 static unsigned int __cpuinit amd_size_cache(struct cpuinfo_x86 *c,
740 /* AMD errata T13 (order #21922) */
743 if (c->x86_model == 3 && c->x86_mask == 0)
745 /* Tbird rev A1/A2 */
746 if (c->x86_model == 4 &&
747 (c->x86_mask == 0 || c->x86_mask == 1))
754 static void __cpuinit cpu_set_tlb_flushall_shift(struct cpuinfo_x86 *c)
756 tlb_flushall_shift = 5;
759 tlb_flushall_shift = 4;
762 static void __cpuinit cpu_detect_tlb_amd(struct cpuinfo_x86 *c)
764 u32 ebx, eax, ecx, edx;
770 if (c->extended_cpuid_level < 0x80000006)
773 cpuid(0x80000006, &eax, &ebx, &ecx, &edx);
775 tlb_lld_4k[ENTRIES] = (ebx >> 16) & mask;
776 tlb_lli_4k[ENTRIES] = ebx & mask;
779 * K8 doesn't have 2M/4M entries in the L2 TLB so read out the L1 TLB
780 * characteristics from the CPUID function 0x80000005 instead.
783 cpuid(0x80000005, &eax, &ebx, &ecx, &edx);
787 /* Handle DTLB 2M and 4M sizes, fall back to L1 if L2 is disabled */
788 if (!((eax >> 16) & mask)) {
791 cpuid(0x80000005, &a, &b, &c, &d);
792 tlb_lld_2m[ENTRIES] = (a >> 16) & 0xff;
794 tlb_lld_2m[ENTRIES] = (eax >> 16) & mask;
797 /* a 4M entry uses two 2M entries */
798 tlb_lld_4m[ENTRIES] = tlb_lld_2m[ENTRIES] >> 1;
800 /* Handle ITLB 2M and 4M sizes, fall back to L1 if L2 is disabled */
803 if (c->x86 == 0x15 && c->x86_model <= 0x1f) {
804 tlb_lli_2m[ENTRIES] = 1024;
806 cpuid(0x80000005, &eax, &ebx, &ecx, &edx);
807 tlb_lli_2m[ENTRIES] = eax & 0xff;
810 tlb_lli_2m[ENTRIES] = eax & mask;
812 tlb_lli_4m[ENTRIES] = tlb_lli_2m[ENTRIES] >> 1;
814 cpu_set_tlb_flushall_shift(c);
817 static const struct cpu_dev __cpuinitconst amd_cpu_dev = {
819 .c_ident = { "AuthenticAMD" },
822 { .vendor = X86_VENDOR_AMD, .family = 4, .model_names =
833 .c_size_cache = amd_size_cache,
835 .c_early_init = early_init_amd,
836 .c_detect_tlb = cpu_detect_tlb_amd,
837 .c_bsp_init = bsp_init_amd,
839 .c_x86_vendor = X86_VENDOR_AMD,
842 cpu_dev_register(amd_cpu_dev);
845 * AMD errata checking
847 * Errata are defined as arrays of ints using the AMD_LEGACY_ERRATUM() or
848 * AMD_OSVW_ERRATUM() macros. The latter is intended for newer errata that
849 * have an OSVW id assigned, which it takes as first argument. Both take a
850 * variable number of family-specific model-stepping ranges created by
851 * AMD_MODEL_RANGE(). Each erratum also has to be declared as extern const
852 * int[] in arch/x86/include/asm/processor.h.
856 * const int amd_erratum_319[] =
857 * AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x10, 0x2, 0x1, 0x4, 0x2),
858 * AMD_MODEL_RANGE(0x10, 0x8, 0x0, 0x8, 0x0),
859 * AMD_MODEL_RANGE(0x10, 0x9, 0x0, 0x9, 0x0));
862 const int amd_erratum_400[] =
863 AMD_OSVW_ERRATUM(1, AMD_MODEL_RANGE(0xf, 0x41, 0x2, 0xff, 0xf),
864 AMD_MODEL_RANGE(0x10, 0x2, 0x1, 0xff, 0xf));
865 EXPORT_SYMBOL_GPL(amd_erratum_400);
867 const int amd_erratum_383[] =
868 AMD_OSVW_ERRATUM(3, AMD_MODEL_RANGE(0x10, 0, 0, 0xff, 0xf));
869 EXPORT_SYMBOL_GPL(amd_erratum_383);
871 bool cpu_has_amd_erratum(const int *erratum)
873 struct cpuinfo_x86 *cpu = __this_cpu_ptr(&cpu_info);
874 int osvw_id = *erratum++;
879 * If called early enough that current_cpu_data hasn't been initialized
880 * yet, fall back to boot_cpu_data.
883 cpu = &boot_cpu_data;
885 if (cpu->x86_vendor != X86_VENDOR_AMD)
888 if (osvw_id >= 0 && osvw_id < 65536 &&
889 cpu_has(cpu, X86_FEATURE_OSVW)) {
892 rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, osvw_len);
893 if (osvw_id < osvw_len) {
896 rdmsrl(MSR_AMD64_OSVW_STATUS + (osvw_id >> 6),
898 return osvw_bits & (1ULL << (osvw_id & 0x3f));
902 /* OSVW unavailable or ID unknown, match family-model-stepping range */
903 ms = (cpu->x86_model << 4) | cpu->x86_mask;
904 while ((range = *erratum++))
905 if ((cpu->x86 == AMD_MODEL_RANGE_FAMILY(range)) &&
906 (ms >= AMD_MODEL_RANGE_START(range)) &&
907 (ms <= AMD_MODEL_RANGE_END(range)))
913 EXPORT_SYMBOL_GPL(cpu_has_amd_erratum);