x86/hyperv: Prevent potential NULL pointer dereference
[muen/linux.git] / arch / x86 / hyperv / hv_init.c
1 /*
2  * X86 specific Hyper-V initialization code.
3  *
4  * Copyright (C) 2016, Microsoft, Inc.
5  *
6  * Author : K. Y. Srinivasan <kys@microsoft.com>
7  *
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms of the GNU General Public License version 2 as published
10  * by the Free Software Foundation.
11  *
12  * This program is distributed in the hope that it will be useful, but
13  * WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
15  * NON INFRINGEMENT.  See the GNU General Public License for more
16  * details.
17  *
18  */
19
20 #include <linux/efi.h>
21 #include <linux/types.h>
22 #include <asm/apic.h>
23 #include <asm/desc.h>
24 #include <asm/hypervisor.h>
25 #include <asm/hyperv-tlfs.h>
26 #include <asm/mshyperv.h>
27 #include <linux/version.h>
28 #include <linux/vmalloc.h>
29 #include <linux/mm.h>
30 #include <linux/clockchips.h>
31 #include <linux/hyperv.h>
32 #include <linux/slab.h>
33 #include <linux/cpuhotplug.h>
34
35 #ifdef CONFIG_HYPERV_TSCPAGE
36
37 static struct ms_hyperv_tsc_page *tsc_pg;
38
39 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
40 {
41         return tsc_pg;
42 }
43 EXPORT_SYMBOL_GPL(hv_get_tsc_page);
44
45 static u64 read_hv_clock_tsc(struct clocksource *arg)
46 {
47         u64 current_tick = hv_read_tsc_page(tsc_pg);
48
49         if (current_tick == U64_MAX)
50                 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
51
52         return current_tick;
53 }
54
55 static struct clocksource hyperv_cs_tsc = {
56                 .name           = "hyperv_clocksource_tsc_page",
57                 .rating         = 400,
58                 .read           = read_hv_clock_tsc,
59                 .mask           = CLOCKSOURCE_MASK(64),
60                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
61 };
62 #endif
63
64 static u64 read_hv_clock_msr(struct clocksource *arg)
65 {
66         u64 current_tick;
67         /*
68          * Read the partition counter to get the current tick count. This count
69          * is set to 0 when the partition is created and is incremented in
70          * 100 nanosecond units.
71          */
72         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
73         return current_tick;
74 }
75
76 static struct clocksource hyperv_cs_msr = {
77         .name           = "hyperv_clocksource_msr",
78         .rating         = 400,
79         .read           = read_hv_clock_msr,
80         .mask           = CLOCKSOURCE_MASK(64),
81         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
82 };
83
84 void *hv_hypercall_pg;
85 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
86 struct clocksource *hyperv_cs;
87 EXPORT_SYMBOL_GPL(hyperv_cs);
88
89 u32 *hv_vp_index;
90 EXPORT_SYMBOL_GPL(hv_vp_index);
91
92 struct hv_vp_assist_page **hv_vp_assist_page;
93 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
94
95 void  __percpu **hyperv_pcpu_input_arg;
96 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
97
98 u32 hv_max_vp_index;
99 EXPORT_SYMBOL_GPL(hv_max_vp_index);
100
101 static int hv_cpu_init(unsigned int cpu)
102 {
103         u64 msr_vp_index;
104         struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
105         void **input_arg;
106         struct page *pg;
107
108         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
109         pg = alloc_page(GFP_KERNEL);
110         if (unlikely(!pg))
111                 return -ENOMEM;
112         *input_arg = page_address(pg);
113
114         hv_get_vp_index(msr_vp_index);
115
116         hv_vp_index[smp_processor_id()] = msr_vp_index;
117
118         if (msr_vp_index > hv_max_vp_index)
119                 hv_max_vp_index = msr_vp_index;
120
121         if (!hv_vp_assist_page)
122                 return 0;
123
124         if (!*hvp)
125                 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
126
127         if (*hvp) {
128                 u64 val;
129
130                 val = vmalloc_to_pfn(*hvp);
131                 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
132                         HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
133
134                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
135         }
136
137         return 0;
138 }
139
140 static void (*hv_reenlightenment_cb)(void);
141
142 static void hv_reenlightenment_notify(struct work_struct *dummy)
143 {
144         struct hv_tsc_emulation_status emu_status;
145
146         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
147
148         /* Don't issue the callback if TSC accesses are not emulated */
149         if (hv_reenlightenment_cb && emu_status.inprogress)
150                 hv_reenlightenment_cb();
151 }
152 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
153
154 void hyperv_stop_tsc_emulation(void)
155 {
156         u64 freq;
157         struct hv_tsc_emulation_status emu_status;
158
159         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
160         emu_status.inprogress = 0;
161         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
162
163         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
164         tsc_khz = div64_u64(freq, 1000);
165 }
166 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
167
168 static inline bool hv_reenlightenment_available(void)
169 {
170         /*
171          * Check for required features and priviliges to make TSC frequency
172          * change notifications work.
173          */
174         return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
175                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
176                 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
177 }
178
179 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
180 {
181         entering_ack_irq();
182
183         inc_irq_stat(irq_hv_reenlightenment_count);
184
185         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
186
187         exiting_irq();
188 }
189
190 void set_hv_tscchange_cb(void (*cb)(void))
191 {
192         struct hv_reenlightenment_control re_ctrl = {
193                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
194                 .enabled = 1,
195                 .target_vp = hv_vp_index[smp_processor_id()]
196         };
197         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
198
199         if (!hv_reenlightenment_available()) {
200                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
201                 return;
202         }
203
204         hv_reenlightenment_cb = cb;
205
206         /* Make sure callback is registered before we write to MSRs */
207         wmb();
208
209         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
210         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
211 }
212 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
213
214 void clear_hv_tscchange_cb(void)
215 {
216         struct hv_reenlightenment_control re_ctrl;
217
218         if (!hv_reenlightenment_available())
219                 return;
220
221         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
222         re_ctrl.enabled = 0;
223         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
224
225         hv_reenlightenment_cb = NULL;
226 }
227 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
228
229 static int hv_cpu_die(unsigned int cpu)
230 {
231         struct hv_reenlightenment_control re_ctrl;
232         unsigned int new_cpu;
233         unsigned long flags;
234         void **input_arg;
235         void *input_pg = NULL;
236
237         local_irq_save(flags);
238         input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
239         input_pg = *input_arg;
240         *input_arg = NULL;
241         local_irq_restore(flags);
242         free_page((unsigned long)input_pg);
243
244         if (hv_vp_assist_page && hv_vp_assist_page[cpu])
245                 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
246
247         if (hv_reenlightenment_cb == NULL)
248                 return 0;
249
250         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
251         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
252                 /* Reassign to some other online CPU */
253                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
254
255                 re_ctrl.target_vp = hv_vp_index[new_cpu];
256                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
257         }
258
259         return 0;
260 }
261
262 static int __init hv_pci_init(void)
263 {
264         int gen2vm = efi_enabled(EFI_BOOT);
265
266         /*
267          * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
268          * The purpose is to suppress the harmless warning:
269          * "PCI: Fatal: No config space access function found"
270          */
271         if (gen2vm)
272                 return 0;
273
274         /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
275         return 1;
276 }
277
278 /*
279  * This function is to be invoked early in the boot sequence after the
280  * hypervisor has been detected.
281  *
282  * 1. Setup the hypercall page.
283  * 2. Register Hyper-V specific clocksource.
284  * 3. Setup Hyper-V specific APIC entry points.
285  */
286 void __init hyperv_init(void)
287 {
288         u64 guest_id, required_msrs;
289         union hv_x64_msr_hypercall_contents hypercall_msr;
290         int cpuhp, i;
291
292         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
293                 return;
294
295         /* Absolutely required MSRs */
296         required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
297                 HV_X64_MSR_VP_INDEX_AVAILABLE;
298
299         if ((ms_hyperv.features & required_msrs) != required_msrs)
300                 return;
301
302         /*
303          * Allocate the per-CPU state for the hypercall input arg.
304          * If this allocation fails, we will not be able to setup
305          * (per-CPU) hypercall input page and thus this failure is
306          * fatal on Hyper-V.
307          */
308         hyperv_pcpu_input_arg = alloc_percpu(void  *);
309
310         BUG_ON(hyperv_pcpu_input_arg == NULL);
311
312         /* Allocate percpu VP index */
313         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
314                                     GFP_KERNEL);
315         if (!hv_vp_index)
316                 return;
317
318         for (i = 0; i < num_possible_cpus(); i++)
319                 hv_vp_index[i] = VP_INVAL;
320
321         hv_vp_assist_page = kcalloc(num_possible_cpus(),
322                                     sizeof(*hv_vp_assist_page), GFP_KERNEL);
323         if (!hv_vp_assist_page) {
324                 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
325                 goto free_vp_index;
326         }
327
328         cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
329                                   hv_cpu_init, hv_cpu_die);
330         if (cpuhp < 0)
331                 goto free_vp_assist_page;
332
333         /*
334          * Setup the hypercall page and enable hypercalls.
335          * 1. Register the guest ID
336          * 2. Enable the hypercall and register the hypercall page
337          */
338         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
339         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
340
341         hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
342         if (hv_hypercall_pg == NULL) {
343                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
344                 goto remove_cpuhp_state;
345         }
346
347         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
348         hypercall_msr.enable = 1;
349         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
350         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
351
352         hv_apic_init();
353
354         x86_init.pci.arch_init = hv_pci_init;
355
356         /*
357          * Register Hyper-V specific clocksource.
358          */
359 #ifdef CONFIG_HYPERV_TSCPAGE
360         if (ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE) {
361                 union hv_x64_msr_hypercall_contents tsc_msr;
362
363                 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
364                 if (!tsc_pg)
365                         goto register_msr_cs;
366
367                 hyperv_cs = &hyperv_cs_tsc;
368
369                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
370
371                 tsc_msr.enable = 1;
372                 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
373
374                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
375
376                 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
377
378                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
379                 return;
380         }
381 register_msr_cs:
382 #endif
383         /*
384          * For 32 bit guests just use the MSR based mechanism for reading
385          * the partition counter.
386          */
387
388         hyperv_cs = &hyperv_cs_msr;
389         if (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)
390                 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
391
392         return;
393
394 remove_cpuhp_state:
395         cpuhp_remove_state(cpuhp);
396 free_vp_assist_page:
397         kfree(hv_vp_assist_page);
398         hv_vp_assist_page = NULL;
399 free_vp_index:
400         kfree(hv_vp_index);
401         hv_vp_index = NULL;
402 }
403
404 /*
405  * This routine is called before kexec/kdump, it does the required cleanup.
406  */
407 void hyperv_cleanup(void)
408 {
409         union hv_x64_msr_hypercall_contents hypercall_msr;
410
411         /* Reset our OS id */
412         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
413
414         /*
415          * Reset hypercall page reference before reset the page,
416          * let hypercall operations fail safely rather than
417          * panic the kernel for using invalid hypercall page
418          */
419         hv_hypercall_pg = NULL;
420
421         /* Reset the hypercall page */
422         hypercall_msr.as_uint64 = 0;
423         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
424
425         /* Reset the TSC page */
426         hypercall_msr.as_uint64 = 0;
427         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
428 }
429 EXPORT_SYMBOL_GPL(hyperv_cleanup);
430
431 void hyperv_report_panic(struct pt_regs *regs, long err)
432 {
433         static bool panic_reported;
434         u64 guest_id;
435
436         /*
437          * We prefer to report panic on 'die' chain as we have proper
438          * registers to report, but if we miss it (e.g. on BUG()) we need
439          * to report it on 'panic'.
440          */
441         if (panic_reported)
442                 return;
443         panic_reported = true;
444
445         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
446
447         wrmsrl(HV_X64_MSR_CRASH_P0, err);
448         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
449         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
450         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
451         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
452
453         /*
454          * Let Hyper-V know there is crash data available
455          */
456         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
457 }
458 EXPORT_SYMBOL_GPL(hyperv_report_panic);
459
460 /**
461  * hyperv_report_panic_msg - report panic message to Hyper-V
462  * @pa: physical address of the panic page containing the message
463  * @size: size of the message in the page
464  */
465 void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
466 {
467         /*
468          * P3 to contain the physical address of the panic page & P4 to
469          * contain the size of the panic data in that page. Rest of the
470          * registers are no-op when the NOTIFY_MSG flag is set.
471          */
472         wrmsrl(HV_X64_MSR_CRASH_P0, 0);
473         wrmsrl(HV_X64_MSR_CRASH_P1, 0);
474         wrmsrl(HV_X64_MSR_CRASH_P2, 0);
475         wrmsrl(HV_X64_MSR_CRASH_P3, pa);
476         wrmsrl(HV_X64_MSR_CRASH_P4, size);
477
478         /*
479          * Let Hyper-V know there is crash data available along with
480          * the panic message.
481          */
482         wrmsrl(HV_X64_MSR_CRASH_CTL,
483                (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
484 }
485 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
486
487 bool hv_is_hyperv_initialized(void)
488 {
489         union hv_x64_msr_hypercall_contents hypercall_msr;
490
491         /*
492          * Ensure that we're really on Hyper-V, and not a KVM or Xen
493          * emulation of Hyper-V
494          */
495         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
496                 return false;
497
498         /*
499          * Verify that earlier initialization succeeded by checking
500          * that the hypercall page is setup
501          */
502         hypercall_msr.as_uint64 = 0;
503         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
504
505         return hypercall_msr.enable;
506 }
507 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);