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Linux/arch/x86/hyperv/hv_init.c

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  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/types.h>
 21 #include <asm/apic.h>
 22 #include <asm/desc.h>
 23 #include <asm/hypervisor.h>
 24 #include <asm/hyperv.h>
 25 #include <asm/mshyperv.h>
 26 #include <linux/version.h>
 27 #include <linux/vmalloc.h>
 28 #include <linux/mm.h>
 29 #include <linux/clockchips.h>
 30 #include <linux/hyperv.h>
 31 #include <linux/slab.h>
 32 #include <linux/cpuhotplug.h>
 33 
 34 #ifdef CONFIG_HYPERV_TSCPAGE
 35 
 36 static struct ms_hyperv_tsc_page *tsc_pg;
 37 
 38 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
 39 {
 40         return tsc_pg;
 41 }
 42 EXPORT_SYMBOL_GPL(hv_get_tsc_page);
 43 
 44 static u64 read_hv_clock_tsc(struct clocksource *arg)
 45 {
 46         u64 current_tick = hv_read_tsc_page(tsc_pg);
 47 
 48         if (current_tick == U64_MAX)
 49                 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 50 
 51         return current_tick;
 52 }
 53 
 54 static struct clocksource hyperv_cs_tsc = {
 55                 .name           = "hyperv_clocksource_tsc_page",
 56                 .rating         = 400,
 57                 .read           = read_hv_clock_tsc,
 58                 .mask           = CLOCKSOURCE_MASK(64),
 59                 .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 60 };
 61 #endif
 62 
 63 static u64 read_hv_clock_msr(struct clocksource *arg)
 64 {
 65         u64 current_tick;
 66         /*
 67          * Read the partition counter to get the current tick count. This count
 68          * is set to 0 when the partition is created and is incremented in
 69          * 100 nanosecond units.
 70          */
 71         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
 72         return current_tick;
 73 }
 74 
 75 static struct clocksource hyperv_cs_msr = {
 76         .name           = "hyperv_clocksource_msr",
 77         .rating         = 400,
 78         .read           = read_hv_clock_msr,
 79         .mask           = CLOCKSOURCE_MASK(64),
 80         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 81 };
 82 
 83 void *hv_hypercall_pg;
 84 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
 85 struct clocksource *hyperv_cs;
 86 EXPORT_SYMBOL_GPL(hyperv_cs);
 87 
 88 u32 *hv_vp_index;
 89 EXPORT_SYMBOL_GPL(hv_vp_index);
 90 
 91 u32 hv_max_vp_index;
 92 
 93 static int hv_cpu_init(unsigned int cpu)
 94 {
 95         u64 msr_vp_index;
 96 
 97         hv_get_vp_index(msr_vp_index);
 98 
 99         hv_vp_index[smp_processor_id()] = msr_vp_index;
100 
101         if (msr_vp_index > hv_max_vp_index)
102                 hv_max_vp_index = msr_vp_index;
103 
104         return 0;
105 }
106 
107 static void (*hv_reenlightenment_cb)(void);
108 
109 static void hv_reenlightenment_notify(struct work_struct *dummy)
110 {
111         struct hv_tsc_emulation_status emu_status;
112 
113         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
114 
115         /* Don't issue the callback if TSC accesses are not emulated */
116         if (hv_reenlightenment_cb && emu_status.inprogress)
117                 hv_reenlightenment_cb();
118 }
119 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
120 
121 void hyperv_stop_tsc_emulation(void)
122 {
123         u64 freq;
124         struct hv_tsc_emulation_status emu_status;
125 
126         rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
127         emu_status.inprogress = 0;
128         wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
129 
130         rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
131         tsc_khz = div64_u64(freq, 1000);
132 }
133 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
134 
135 static inline bool hv_reenlightenment_available(void)
136 {
137         /*
138          * Check for required features and priviliges to make TSC frequency
139          * change notifications work.
140          */
141         return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
142                 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
143                 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
144 }
145 
146 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
147 {
148         entering_ack_irq();
149 
150         inc_irq_stat(irq_hv_reenlightenment_count);
151 
152         schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
153 
154         exiting_irq();
155 }
156 
157 void set_hv_tscchange_cb(void (*cb)(void))
158 {
159         struct hv_reenlightenment_control re_ctrl = {
160                 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
161                 .enabled = 1,
162                 .target_vp = hv_vp_index[smp_processor_id()]
163         };
164         struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
165 
166         if (!hv_reenlightenment_available()) {
167                 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
168                 return;
169         }
170 
171         hv_reenlightenment_cb = cb;
172 
173         /* Make sure callback is registered before we write to MSRs */
174         wmb();
175 
176         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
177         wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
178 }
179 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
180 
181 void clear_hv_tscchange_cb(void)
182 {
183         struct hv_reenlightenment_control re_ctrl;
184 
185         if (!hv_reenlightenment_available())
186                 return;
187 
188         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
189         re_ctrl.enabled = 0;
190         wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
191 
192         hv_reenlightenment_cb = NULL;
193 }
194 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
195 
196 static int hv_cpu_die(unsigned int cpu)
197 {
198         struct hv_reenlightenment_control re_ctrl;
199         unsigned int new_cpu;
200 
201         if (hv_reenlightenment_cb == NULL)
202                 return 0;
203 
204         rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
205         if (re_ctrl.target_vp == hv_vp_index[cpu]) {
206                 /* Reassign to some other online CPU */
207                 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
208 
209                 re_ctrl.target_vp = hv_vp_index[new_cpu];
210                 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
211         }
212 
213         return 0;
214 }
215 
216 /*
217  * This function is to be invoked early in the boot sequence after the
218  * hypervisor has been detected.
219  *
220  * 1. Setup the hypercall page.
221  * 2. Register Hyper-V specific clocksource.
222  */
223 void hyperv_init(void)
224 {
225         u64 guest_id, required_msrs;
226         union hv_x64_msr_hypercall_contents hypercall_msr;
227 
228         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
229                 return;
230 
231         /* Absolutely required MSRs */
232         required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
233                 HV_X64_MSR_VP_INDEX_AVAILABLE;
234 
235         if ((ms_hyperv.features & required_msrs) != required_msrs)
236                 return;
237 
238         /* Allocate percpu VP index */
239         hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
240                                     GFP_KERNEL);
241         if (!hv_vp_index)
242                 return;
243 
244         if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
245                               hv_cpu_init, hv_cpu_die) < 0)
246                 goto free_vp_index;
247 
248         /*
249          * Setup the hypercall page and enable hypercalls.
250          * 1. Register the guest ID
251          * 2. Enable the hypercall and register the hypercall page
252          */
253         guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
254         wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
255 
256         hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
257         if (hv_hypercall_pg == NULL) {
258                 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
259                 goto free_vp_index;
260         }
261 
262         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
263         hypercall_msr.enable = 1;
264         hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
265         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
266 
267         hyper_alloc_mmu();
268 
269         /*
270          * Register Hyper-V specific clocksource.
271          */
272 #ifdef CONFIG_HYPERV_TSCPAGE
273         if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
274                 union hv_x64_msr_hypercall_contents tsc_msr;
275 
276                 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
277                 if (!tsc_pg)
278                         goto register_msr_cs;
279 
280                 hyperv_cs = &hyperv_cs_tsc;
281 
282                 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
283 
284                 tsc_msr.enable = 1;
285                 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
286 
287                 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
288 
289                 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
290 
291                 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
292                 return;
293         }
294 register_msr_cs:
295 #endif
296         /*
297          * For 32 bit guests just use the MSR based mechanism for reading
298          * the partition counter.
299          */
300 
301         hyperv_cs = &hyperv_cs_msr;
302         if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
303                 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
304 
305         return;
306 
307 free_vp_index:
308         kfree(hv_vp_index);
309         hv_vp_index = NULL;
310 }
311 
312 /*
313  * This routine is called before kexec/kdump, it does the required cleanup.
314  */
315 void hyperv_cleanup(void)
316 {
317         union hv_x64_msr_hypercall_contents hypercall_msr;
318 
319         /* Reset our OS id */
320         wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
321 
322         /* Reset the hypercall page */
323         hypercall_msr.as_uint64 = 0;
324         wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
325 
326         /* Reset the TSC page */
327         hypercall_msr.as_uint64 = 0;
328         wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
329 }
330 EXPORT_SYMBOL_GPL(hyperv_cleanup);
331 
332 void hyperv_report_panic(struct pt_regs *regs, long err)
333 {
334         static bool panic_reported;
335         u64 guest_id;
336 
337         /*
338          * We prefer to report panic on 'die' chain as we have proper
339          * registers to report, but if we miss it (e.g. on BUG()) we need
340          * to report it on 'panic'.
341          */
342         if (panic_reported)
343                 return;
344         panic_reported = true;
345 
346         rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
347 
348         wrmsrl(HV_X64_MSR_CRASH_P0, err);
349         wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
350         wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
351         wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
352         wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
353 
354         /*
355          * Let Hyper-V know there is crash data available
356          */
357         wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
358 }
359 EXPORT_SYMBOL_GPL(hyperv_report_panic);
360 
361 bool hv_is_hyperv_initialized(void)
362 {
363         union hv_x64_msr_hypercall_contents hypercall_msr;
364 
365         /*
366          * Ensure that we're really on Hyper-V, and not a KVM or Xen
367          * emulation of Hyper-V
368          */
369         if (x86_hyper_type != X86_HYPER_MS_HYPERV)
370                 return false;
371 
372         /*
373          * Verify that earlier initialization succeeded by checking
374          * that the hypercall page is setup
375          */
376         hypercall_msr.as_uint64 = 0;
377         rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
378 
379         return hypercall_msr.enable;
380 }
381 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
382 

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