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mm: abstract the vma_merge()/split_vma() pattern for mprotect() et al.
[linux.git] / arch / x86 / hyperv / hv_init.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * X86 specific Hyper-V initialization code.
4  *
5  * Copyright (C) 2016, Microsoft, Inc.
6  *
7  * Author : K. Y. Srinivasan <[email protected]>
8  */
9
10 #include <linux/efi.h>
11 #include <linux/types.h>
12 #include <linux/bitfield.h>
13 #include <linux/io.h>
14 #include <asm/apic.h>
15 #include <asm/desc.h>
16 #include <asm/sev.h>
17 #include <asm/ibt.h>
18 #include <asm/hypervisor.h>
19 #include <asm/hyperv-tlfs.h>
20 #include <asm/mshyperv.h>
21 #include <asm/idtentry.h>
22 #include <asm/set_memory.h>
23 #include <linux/kexec.h>
24 #include <linux/version.h>
25 #include <linux/vmalloc.h>
26 #include <linux/mm.h>
27 #include <linux/hyperv.h>
28 #include <linux/slab.h>
29 #include <linux/kernel.h>
30 #include <linux/cpuhotplug.h>
31 #include <linux/syscore_ops.h>
32 #include <clocksource/hyperv_timer.h>
33 #include <linux/highmem.h>
34
35 int hyperv_init_cpuhp;
36 u64 hv_current_partition_id = ~0ull;
37 EXPORT_SYMBOL_GPL(hv_current_partition_id);
38
39 void *hv_hypercall_pg;
40 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
41
42 union hv_ghcb * __percpu *hv_ghcb_pg;
43
44 /* Storage to save the hypercall page temporarily for hibernation */
45 static void *hv_hypercall_pg_saved;
46
47 struct hv_vp_assist_page **hv_vp_assist_page;
48 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
49
50 static int hyperv_init_ghcb(void)
51 {
52         u64 ghcb_gpa;
53         void *ghcb_va;
54         void **ghcb_base;
55
56         if (!ms_hyperv.paravisor_present || !hv_isolation_type_snp())
57                 return 0;
58
59         if (!hv_ghcb_pg)
60                 return -EINVAL;
61
62         /*
63          * GHCB page is allocated by paravisor. The address
64          * returned by MSR_AMD64_SEV_ES_GHCB is above shared
65          * memory boundary and map it here.
66          */
67         rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
68
69         /* Mask out vTOM bit. ioremap_cache() maps decrypted */
70         ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary;
71         ghcb_va = (void *)ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE);
72         if (!ghcb_va)
73                 return -ENOMEM;
74
75         ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
76         *ghcb_base = ghcb_va;
77
78         return 0;
79 }
80
81 static int hv_cpu_init(unsigned int cpu)
82 {
83         union hv_vp_assist_msr_contents msr = { 0 };
84         struct hv_vp_assist_page **hvp;
85         int ret;
86
87         ret = hv_common_cpu_init(cpu);
88         if (ret)
89                 return ret;
90
91         if (!hv_vp_assist_page)
92                 return 0;
93
94         hvp = &hv_vp_assist_page[cpu];
95         if (hv_root_partition) {
96                 /*
97                  * For root partition we get the hypervisor provided VP assist
98                  * page, instead of allocating a new page.
99                  */
100                 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
101                 *hvp = memremap(msr.pfn << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT,
102                                 PAGE_SIZE, MEMREMAP_WB);
103         } else {
104                 /*
105                  * The VP assist page is an "overlay" page (see Hyper-V TLFS's
106                  * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
107                  * out to make sure we always write the EOI MSR in
108                  * hv_apic_eoi_write() *after* the EOI optimization is disabled
109                  * in hv_cpu_die(), otherwise a CPU may not be stopped in the
110                  * case of CPU offlining and the VM will hang.
111                  */
112                 if (!*hvp) {
113                         *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
114
115                         /*
116                          * Hyper-V should never specify a VM that is a Confidential
117                          * VM and also running in the root partition. Root partition
118                          * is blocked to run in Confidential VM. So only decrypt assist
119                          * page in non-root partition here.
120                          */
121                         if (*hvp && !ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
122                                 WARN_ON_ONCE(set_memory_decrypted((unsigned long)(*hvp), 1));
123                                 memset(*hvp, 0, PAGE_SIZE);
124                         }
125                 }
126
127                 if (*hvp)
128                         msr.pfn = vmalloc_to_pfn(*hvp);
129
130         }
131         if (!WARN_ON(!(*hvp))) {
132                 msr.enable = 1;
133                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
134         }
135
136         return hyperv_init_ghcb();
137 }
138
139 static void (*hv_reenlightenment_cb)(void);
140
141 static void hv_reenlightenment_notify(struct work_struct *dummy)
142 {
143         struct hv_tsc_emulation_status emu_status;
144
145         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
146
147         /* Don't issue the callback if TSC accesses are not emulated */
148         if (hv_reenlightenment_cb && emu_status.inprogress)
149                 hv_reenlightenment_cb();
150 }
151 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
152
153 void hyperv_stop_tsc_emulation(void)
154 {
155         u64 freq;
156         struct hv_tsc_emulation_status emu_status;
157
158         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
159         emu_status.inprogress = 0;
160         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
161
162         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
163         tsc_khz = div64_u64(freq, 1000);
164 }
165 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
166
167 static inline bool hv_reenlightenment_available(void)
168 {
169         /*
170          * Check for required features and privileges to make TSC frequency
171          * change notifications work.
172          */
173         return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
174                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
175                 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
176 }
177
178 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
179 {
180         apic_eoi();
181         inc_irq_stat(irq_hv_reenlightenment_count);
182         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
183 }
184
185 void set_hv_tscchange_cb(void (*cb)(void))
186 {
187         struct hv_reenlightenment_control re_ctrl = {
188                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
189                 .enabled = 1,
190         };
191         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
192
193         if (!hv_reenlightenment_available()) {
194                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
195                 return;
196         }
197
198         if (!hv_vp_index)
199                 return;
200
201         hv_reenlightenment_cb = cb;
202
203         /* Make sure callback is registered before we write to MSRs */
204         wmb();
205
206         re_ctrl.target_vp = hv_vp_index[get_cpu()];
207
208         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
209         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
210
211         put_cpu();
212 }
213 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
214
215 void clear_hv_tscchange_cb(void)
216 {
217         struct hv_reenlightenment_control re_ctrl;
218
219         if (!hv_reenlightenment_available())
220                 return;
221
222         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
223         re_ctrl.enabled = 0;
224         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
225
226         hv_reenlightenment_cb = NULL;
227 }
228 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
229
230 static int hv_cpu_die(unsigned int cpu)
231 {
232         struct hv_reenlightenment_control re_ctrl;
233         unsigned int new_cpu;
234         void **ghcb_va;
235
236         if (hv_ghcb_pg) {
237                 ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
238                 if (*ghcb_va)
239                         iounmap(*ghcb_va);
240                 *ghcb_va = NULL;
241         }
242
243         hv_common_cpu_die(cpu);
244
245         if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
246                 union hv_vp_assist_msr_contents msr = { 0 };
247                 if (hv_root_partition) {
248                         /*
249                          * For root partition the VP assist page is mapped to
250                          * hypervisor provided page, and thus we unmap the
251                          * page here and nullify it, so that in future we have
252                          * correct page address mapped in hv_cpu_init.
253                          */
254                         memunmap(hv_vp_assist_page[cpu]);
255                         hv_vp_assist_page[cpu] = NULL;
256                         rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
257                         msr.enable = 0;
258                 }
259                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
260         }
261
262         if (hv_reenlightenment_cb == NULL)
263                 return 0;
264
265         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
266         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
267                 /*
268                  * Reassign reenlightenment notifications to some other online
269                  * CPU or just disable the feature if there are no online CPUs
270                  * left (happens on hibernation).
271                  */
272                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
273
274                 if (new_cpu < nr_cpu_ids)
275                         re_ctrl.target_vp = hv_vp_index[new_cpu];
276                 else
277                         re_ctrl.enabled = 0;
278
279                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
280         }
281
282         return 0;
283 }
284
285 static int __init hv_pci_init(void)
286 {
287         int gen2vm = efi_enabled(EFI_BOOT);
288
289         /*
290          * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
291          * The purpose is to suppress the harmless warning:
292          * "PCI: Fatal: No config space access function found"
293          */
294         if (gen2vm)
295                 return 0;
296
297         /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
298         return 1;
299 }
300
301 static int hv_suspend(void)
302 {
303         union hv_x64_msr_hypercall_contents hypercall_msr;
304         int ret;
305
306         if (hv_root_partition)
307                 return -EPERM;
308
309         /*
310          * Reset the hypercall page as it is going to be invalidated
311          * across hibernation. Setting hv_hypercall_pg to NULL ensures
312          * that any subsequent hypercall operation fails safely instead of
313          * crashing due to an access of an invalid page. The hypercall page
314          * pointer is restored on resume.
315          */
316         hv_hypercall_pg_saved = hv_hypercall_pg;
317         hv_hypercall_pg = NULL;
318
319         /* Disable the hypercall page in the hypervisor */
320         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
321         hypercall_msr.enable = 0;
322         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
323
324         ret = hv_cpu_die(0);
325         return ret;
326 }
327
328 static void hv_resume(void)
329 {
330         union hv_x64_msr_hypercall_contents hypercall_msr;
331         int ret;
332
333         ret = hv_cpu_init(0);
334         WARN_ON(ret);
335
336         /* Re-enable the hypercall page */
337         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
338         hypercall_msr.enable = 1;
339         hypercall_msr.guest_physical_address =
340                 vmalloc_to_pfn(hv_hypercall_pg_saved);
341         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
342
343         hv_hypercall_pg = hv_hypercall_pg_saved;
344         hv_hypercall_pg_saved = NULL;
345
346         /*
347          * Reenlightenment notifications are disabled by hv_cpu_die(0),
348          * reenable them here if hv_reenlightenment_cb was previously set.
349          */
350         if (hv_reenlightenment_cb)
351                 set_hv_tscchange_cb(hv_reenlightenment_cb);
352 }
353
354 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
355 static struct syscore_ops hv_syscore_ops = {
356         .suspend        = hv_suspend,
357         .resume         = hv_resume,
358 };
359
360 static void (* __initdata old_setup_percpu_clockev)(void);
361
362 static void __init hv_stimer_setup_percpu_clockev(void)
363 {
364         /*
365          * Ignore any errors in setting up stimer clockevents
366          * as we can run with the LAPIC timer as a fallback.
367          */
368         (void)hv_stimer_alloc(false);
369
370         /*
371          * Still register the LAPIC timer, because the direct-mode STIMER is
372          * not supported by old versions of Hyper-V. This also allows users
373          * to switch to LAPIC timer via /sys, if they want to.
374          */
375         if (old_setup_percpu_clockev)
376                 old_setup_percpu_clockev();
377 }
378
379 static void __init hv_get_partition_id(void)
380 {
381         struct hv_get_partition_id *output_page;
382         u64 status;
383         unsigned long flags;
384
385         local_irq_save(flags);
386         output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
387         status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
388         if (!hv_result_success(status)) {
389                 /* No point in proceeding if this failed */
390                 pr_err("Failed to get partition ID: %lld\n", status);
391                 BUG();
392         }
393         hv_current_partition_id = output_page->partition_id;
394         local_irq_restore(flags);
395 }
396
397 static u8 __init get_vtl(void)
398 {
399         u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
400         struct hv_get_vp_registers_input *input;
401         struct hv_get_vp_registers_output *output;
402         unsigned long flags;
403         u64 ret;
404
405         local_irq_save(flags);
406         input = *this_cpu_ptr(hyperv_pcpu_input_arg);
407         output = (struct hv_get_vp_registers_output *)input;
408
409         memset(input, 0, struct_size(input, element, 1));
410         input->header.partitionid = HV_PARTITION_ID_SELF;
411         input->header.vpindex = HV_VP_INDEX_SELF;
412         input->header.inputvtl = 0;
413         input->element[0].name0 = HV_X64_REGISTER_VSM_VP_STATUS;
414
415         ret = hv_do_hypercall(control, input, output);
416         if (hv_result_success(ret)) {
417                 ret = output->as64.low & HV_X64_VTL_MASK;
418         } else {
419                 pr_err("Failed to get VTL(%lld) and set VTL to zero by default.\n", ret);
420                 ret = 0;
421         }
422
423         local_irq_restore(flags);
424         return ret;
425 }
426
427 /*
428  * This function is to be invoked early in the boot sequence after the
429  * hypervisor has been detected.
430  *
431  * 1. Setup the hypercall page.
432  * 2. Register Hyper-V specific clocksource.
433  * 3. Setup Hyper-V specific APIC entry points.
434  */
435 void __init hyperv_init(void)
436 {
437         u64 guest_id;
438         union hv_x64_msr_hypercall_contents hypercall_msr;
439         int cpuhp;
440
441         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
442                 return;
443
444         if (hv_common_init())
445                 return;
446
447         /*
448          * The VP assist page is useless to a TDX guest: the only use we
449          * would have for it is lazy EOI, which can not be used with TDX.
450          */
451         if (hv_isolation_type_tdx())
452                 hv_vp_assist_page = NULL;
453         else
454                 hv_vp_assist_page = kcalloc(num_possible_cpus(),
455                                             sizeof(*hv_vp_assist_page),
456                                             GFP_KERNEL);
457         if (!hv_vp_assist_page) {
458                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
459
460                 if (!hv_isolation_type_tdx())
461                         goto common_free;
462         }
463
464         if (ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
465                 /* Negotiate GHCB Version. */
466                 if (!hv_ghcb_negotiate_protocol())
467                         hv_ghcb_terminate(SEV_TERM_SET_GEN,
468                                           GHCB_SEV_ES_PROT_UNSUPPORTED);
469
470                 hv_ghcb_pg = alloc_percpu(union hv_ghcb *);
471                 if (!hv_ghcb_pg)
472                         goto free_vp_assist_page;
473         }
474
475         cpuhp = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "x86/hyperv_init:online",
476                                   hv_cpu_init, hv_cpu_die);
477         if (cpuhp < 0)
478                 goto free_ghcb_page;
479
480         /*
481          * Setup the hypercall page and enable hypercalls.
482          * 1. Register the guest ID
483          * 2. Enable the hypercall and register the hypercall page
484          *
485          * A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg:
486          * when the hypercall input is a page, such a VM must pass a decrypted
487          * page to Hyper-V, e.g. hv_post_message() uses the per-CPU page
488          * hyperv_pcpu_input_arg, which is decrypted if no paravisor is present.
489          *
490          * A TDX VM with the paravisor uses hv_hypercall_pg for most hypercalls,
491          * which are handled by the paravisor and the VM must use an encrypted
492          * input page: in such a VM, the hyperv_pcpu_input_arg is encrypted and
493          * used in the hypercalls, e.g. see hv_mark_gpa_visibility() and
494          * hv_arch_irq_unmask(). Such a VM uses TDX GHCI for two hypercalls:
495          * 1. HVCALL_SIGNAL_EVENT: see vmbus_set_event() and _hv_do_fast_hypercall8().
496          * 2. HVCALL_POST_MESSAGE: the input page must be a decrypted page, i.e.
497          * hv_post_message() in such a VM can't use the encrypted hyperv_pcpu_input_arg;
498          * instead, hv_post_message() uses the post_msg_page, which is decrypted
499          * in such a VM and is only used in such a VM.
500          */
501         guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
502         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
503
504         /* With the paravisor, the VM must also write the ID via GHCB/GHCI */
505         hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);
506
507         /* A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg */
508         if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
509                 goto skip_hypercall_pg_init;
510
511         hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
512                         VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
513                         VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
514                         __builtin_return_address(0));
515         if (hv_hypercall_pg == NULL)
516                 goto clean_guest_os_id;
517
518         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
519         hypercall_msr.enable = 1;
520
521         if (hv_root_partition) {
522                 struct page *pg;
523                 void *src;
524
525                 /*
526                  * For the root partition, the hypervisor will set up its
527                  * hypercall page. The hypervisor guarantees it will not show
528                  * up in the root's address space. The root can't change the
529                  * location of the hypercall page.
530                  *
531                  * Order is important here. We must enable the hypercall page
532                  * so it is populated with code, then copy the code to an
533                  * executable page.
534                  */
535                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
536
537                 pg = vmalloc_to_page(hv_hypercall_pg);
538                 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
539                                 MEMREMAP_WB);
540                 BUG_ON(!src);
541                 memcpy_to_page(pg, 0, src, HV_HYP_PAGE_SIZE);
542                 memunmap(src);
543
544                 hv_remap_tsc_clocksource();
545         } else {
546                 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
547                 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
548         }
549
550 skip_hypercall_pg_init:
551         /*
552          * Some versions of Hyper-V that provide IBT in guest VMs have a bug
553          * in that there's no ENDBR64 instruction at the entry to the
554          * hypercall page. Because hypercalls are invoked via an indirect call
555          * to the hypercall page, all hypercall attempts fail when IBT is
556          * enabled, and Linux panics. For such buggy versions, disable IBT.
557          *
558          * Fixed versions of Hyper-V always provide ENDBR64 on the hypercall
559          * page, so if future Linux kernel versions enable IBT for 32-bit
560          * builds, additional hypercall page hackery will be required here
561          * to provide an ENDBR32.
562          */
563 #ifdef CONFIG_X86_KERNEL_IBT
564         if (cpu_feature_enabled(X86_FEATURE_IBT) &&
565             *(u32 *)hv_hypercall_pg != gen_endbr()) {
566                 setup_clear_cpu_cap(X86_FEATURE_IBT);
567                 pr_warn("Hyper-V: Disabling IBT because of Hyper-V bug\n");
568         }
569 #endif
570
571         /*
572          * hyperv_init() is called before LAPIC is initialized: see
573          * apic_intr_mode_init() -> x86_platform.apic_post_init() and
574          * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
575          * depends on LAPIC, so hv_stimer_alloc() should be called from
576          * x86_init.timers.setup_percpu_clockev.
577          */
578         old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
579         x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;
580
581         hv_apic_init();
582
583         x86_init.pci.arch_init = hv_pci_init;
584
585         register_syscore_ops(&hv_syscore_ops);
586
587         hyperv_init_cpuhp = cpuhp;
588
589         if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
590                 hv_get_partition_id();
591
592         BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
593
594 #ifdef CONFIG_PCI_MSI
595         /*
596          * If we're running as root, we want to create our own PCI MSI domain.
597          * We can't set this in hv_pci_init because that would be too late.
598          */
599         if (hv_root_partition)
600                 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
601 #endif
602
603         /* Query the VMs extended capability once, so that it can be cached. */
604         hv_query_ext_cap(0);
605
606         /* Find the VTL */
607         if (!ms_hyperv.paravisor_present && hv_isolation_type_snp())
608                 ms_hyperv.vtl = get_vtl();
609
610         return;
611
612 clean_guest_os_id:
613         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
614         hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
615         cpuhp_remove_state(cpuhp);
616 free_ghcb_page:
617         free_percpu(hv_ghcb_pg);
618 free_vp_assist_page:
619         kfree(hv_vp_assist_page);
620         hv_vp_assist_page = NULL;
621 common_free:
622         hv_common_free();
623 }
624
625 /*
626  * This routine is called before kexec/kdump, it does the required cleanup.
627  */
628 void hyperv_cleanup(void)
629 {
630         union hv_x64_msr_hypercall_contents hypercall_msr;
631         union hv_reference_tsc_msr tsc_msr;
632
633         /* Reset our OS id */
634         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
635         hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
636
637         /*
638          * Reset hypercall page reference before reset the page,
639          * let hypercall operations fail safely rather than
640          * panic the kernel for using invalid hypercall page
641          */
642         hv_hypercall_pg = NULL;
643
644         /* Reset the hypercall page */
645         hypercall_msr.as_uint64 = hv_get_register(HV_X64_MSR_HYPERCALL);
646         hypercall_msr.enable = 0;
647         hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
648
649         /* Reset the TSC page */
650         tsc_msr.as_uint64 = hv_get_register(HV_X64_MSR_REFERENCE_TSC);
651         tsc_msr.enable = 0;
652         hv_set_register(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
653 }
654
655 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
656 {
657         static bool panic_reported;
658         u64 guest_id;
659
660         if (in_die && !panic_on_oops)
661                 return;
662
663         /*
664          * We prefer to report panic on 'die' chain as we have proper
665          * registers to report, but if we miss it (e.g. on BUG()) we need
666          * to report it on 'panic'.
667          */
668         if (panic_reported)
669                 return;
670         panic_reported = true;
671
672         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
673
674         wrmsrl(HV_X64_MSR_CRASH_P0, err);
675         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
676         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
677         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
678         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
679
680         /*
681          * Let Hyper-V know there is crash data available
682          */
683         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
684 }
685 EXPORT_SYMBOL_GPL(hyperv_report_panic);
686
687 bool hv_is_hyperv_initialized(void)
688 {
689         union hv_x64_msr_hypercall_contents hypercall_msr;
690
691         /*
692          * Ensure that we're really on Hyper-V, and not a KVM or Xen
693          * emulation of Hyper-V
694          */
695         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
696                 return false;
697
698         /* A TDX VM with no paravisor uses TDX GHCI call rather than hv_hypercall_pg */
699         if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
700                 return true;
701         /*
702          * Verify that earlier initialization succeeded by checking
703          * that the hypercall page is setup
704          */
705         hypercall_msr.as_uint64 = 0;
706         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
707
708         return hypercall_msr.enable;
709 }
710 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
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