xref: /openbmc/linux/arch/x86/hyperv/hv_init.c (revision 68198dca)
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/hypervisor.h>
22 #include <asm/hyperv.h>
23 #include <asm/mshyperv.h>
24 #include <linux/version.h>
25 #include <linux/vmalloc.h>
26 #include <linux/mm.h>
27 #include <linux/clockchips.h>
28 #include <linux/hyperv.h>
29 #include <linux/slab.h>
30 #include <linux/cpuhotplug.h>
31 
32 #ifdef CONFIG_HYPERV_TSCPAGE
33 
34 static struct ms_hyperv_tsc_page *tsc_pg;
35 
36 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
37 {
38 	return tsc_pg;
39 }
40 
41 static u64 read_hv_clock_tsc(struct clocksource *arg)
42 {
43 	u64 current_tick = hv_read_tsc_page(tsc_pg);
44 
45 	if (current_tick == U64_MAX)
46 		rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
47 
48 	return current_tick;
49 }
50 
51 static struct clocksource hyperv_cs_tsc = {
52 		.name		= "hyperv_clocksource_tsc_page",
53 		.rating		= 400,
54 		.read		= read_hv_clock_tsc,
55 		.mask		= CLOCKSOURCE_MASK(64),
56 		.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
57 };
58 #endif
59 
60 static u64 read_hv_clock_msr(struct clocksource *arg)
61 {
62 	u64 current_tick;
63 	/*
64 	 * Read the partition counter to get the current tick count. This count
65 	 * is set to 0 when the partition is created and is incremented in
66 	 * 100 nanosecond units.
67 	 */
68 	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
69 	return current_tick;
70 }
71 
72 static struct clocksource hyperv_cs_msr = {
73 	.name		= "hyperv_clocksource_msr",
74 	.rating		= 400,
75 	.read		= read_hv_clock_msr,
76 	.mask		= CLOCKSOURCE_MASK(64),
77 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
78 };
79 
80 void *hv_hypercall_pg;
81 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
82 struct clocksource *hyperv_cs;
83 EXPORT_SYMBOL_GPL(hyperv_cs);
84 
85 u32 *hv_vp_index;
86 EXPORT_SYMBOL_GPL(hv_vp_index);
87 
88 u32 hv_max_vp_index;
89 
90 static int hv_cpu_init(unsigned int cpu)
91 {
92 	u64 msr_vp_index;
93 
94 	hv_get_vp_index(msr_vp_index);
95 
96 	hv_vp_index[smp_processor_id()] = msr_vp_index;
97 
98 	if (msr_vp_index > hv_max_vp_index)
99 		hv_max_vp_index = msr_vp_index;
100 
101 	return 0;
102 }
103 
104 /*
105  * This function is to be invoked early in the boot sequence after the
106  * hypervisor has been detected.
107  *
108  * 1. Setup the hypercall page.
109  * 2. Register Hyper-V specific clocksource.
110  */
111 void hyperv_init(void)
112 {
113 	u64 guest_id;
114 	union hv_x64_msr_hypercall_contents hypercall_msr;
115 
116 	if (x86_hyper_type != X86_HYPER_MS_HYPERV)
117 		return;
118 
119 	/* Allocate percpu VP index */
120 	hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
121 				    GFP_KERNEL);
122 	if (!hv_vp_index)
123 		return;
124 
125 	if (cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
126 			      hv_cpu_init, NULL) < 0)
127 		goto free_vp_index;
128 
129 	/*
130 	 * Setup the hypercall page and enable hypercalls.
131 	 * 1. Register the guest ID
132 	 * 2. Enable the hypercall and register the hypercall page
133 	 */
134 	guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
135 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
136 
137 	hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
138 	if (hv_hypercall_pg == NULL) {
139 		wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
140 		goto free_vp_index;
141 	}
142 
143 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
144 	hypercall_msr.enable = 1;
145 	hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
146 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
147 
148 	hyper_alloc_mmu();
149 
150 	/*
151 	 * Register Hyper-V specific clocksource.
152 	 */
153 #ifdef CONFIG_HYPERV_TSCPAGE
154 	if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
155 		union hv_x64_msr_hypercall_contents tsc_msr;
156 
157 		tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
158 		if (!tsc_pg)
159 			goto register_msr_cs;
160 
161 		hyperv_cs = &hyperv_cs_tsc;
162 
163 		rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
164 
165 		tsc_msr.enable = 1;
166 		tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
167 
168 		wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
169 
170 		hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
171 
172 		clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
173 		return;
174 	}
175 register_msr_cs:
176 #endif
177 	/*
178 	 * For 32 bit guests just use the MSR based mechanism for reading
179 	 * the partition counter.
180 	 */
181 
182 	hyperv_cs = &hyperv_cs_msr;
183 	if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
184 		clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
185 
186 	return;
187 
188 free_vp_index:
189 	kfree(hv_vp_index);
190 	hv_vp_index = NULL;
191 }
192 
193 /*
194  * This routine is called before kexec/kdump, it does the required cleanup.
195  */
196 void hyperv_cleanup(void)
197 {
198 	union hv_x64_msr_hypercall_contents hypercall_msr;
199 
200 	/* Reset our OS id */
201 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
202 
203 	/* Reset the hypercall page */
204 	hypercall_msr.as_uint64 = 0;
205 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
206 
207 	/* Reset the TSC page */
208 	hypercall_msr.as_uint64 = 0;
209 	wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
210 }
211 EXPORT_SYMBOL_GPL(hyperv_cleanup);
212 
213 void hyperv_report_panic(struct pt_regs *regs, long err)
214 {
215 	static bool panic_reported;
216 	u64 guest_id;
217 
218 	/*
219 	 * We prefer to report panic on 'die' chain as we have proper
220 	 * registers to report, but if we miss it (e.g. on BUG()) we need
221 	 * to report it on 'panic'.
222 	 */
223 	if (panic_reported)
224 		return;
225 	panic_reported = true;
226 
227 	rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
228 
229 	wrmsrl(HV_X64_MSR_CRASH_P0, err);
230 	wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
231 	wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
232 	wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
233 	wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
234 
235 	/*
236 	 * Let Hyper-V know there is crash data available
237 	 */
238 	wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
239 }
240 EXPORT_SYMBOL_GPL(hyperv_report_panic);
241 
242 bool hv_is_hypercall_page_setup(void)
243 {
244 	union hv_x64_msr_hypercall_contents hypercall_msr;
245 
246 	/* Check if the hypercall page is setup */
247 	hypercall_msr.as_uint64 = 0;
248 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
249 
250 	if (!hypercall_msr.enable)
251 		return false;
252 
253 	return true;
254 }
255 EXPORT_SYMBOL_GPL(hv_is_hypercall_page_setup);
256