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1 // SPDX-License-Identifier: GPL-2.0
2 
3 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
4 #include <linux/memblock.h>
5 #endif
6 #include <linux/console.h>
7 #include <linux/cpu.h>
8 #include <linux/kexec.h>
9 #include <linux/slab.h>
10 #include <linux/panic_notifier.h>
11 
12 #include <xen/xen.h>
13 #include <xen/features.h>
14 #include <xen/interface/sched.h>
15 #include <xen/interface/version.h>
16 #include <xen/page.h>
17 
18 #include <asm/xen/hypercall.h>
19 #include <asm/xen/hypervisor.h>
20 #include <asm/cpu.h>
21 #include <asm/e820/api.h>
22 #include <asm/setup.h>
23 
24 #include "xen-ops.h"
25 #include "smp.h"
26 #include "pmu.h"
27 
28 EXPORT_SYMBOL_GPL(hypercall_page);
29 
30 /*
31  * Pointer to the xen_vcpu_info structure or
32  * &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
33  * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
34  * but if the hypervisor supports VCPUOP_register_vcpu_info then it can point
35  * to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to
36  * acknowledge pending events.
37  * Also more subtly it is used by the patched version of irq enable/disable
38  * e.g. xen_irq_enable_direct and xen_iret in PV mode.
39  *
40  * The desire to be able to do those mask/unmask operations as a single
41  * instruction by using the per-cpu offset held in %gs is the real reason
42  * vcpu info is in a per-cpu pointer and the original reason for this
43  * hypercall.
44  *
45  */
46 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
47 
48 /*
49  * Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info
50  * hypercall. This can be used both in PV and PVHVM mode. The structure
51  * overrides the default per_cpu(xen_vcpu, cpu) value.
52  */
53 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
54 
55 /* Linux <-> Xen vCPU id mapping */
56 DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
57 EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
58 
59 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
60 EXPORT_SYMBOL(machine_to_phys_mapping);
61 unsigned long  machine_to_phys_nr;
62 EXPORT_SYMBOL(machine_to_phys_nr);
63 
64 struct start_info *xen_start_info;
65 EXPORT_SYMBOL_GPL(xen_start_info);
66 
67 struct shared_info xen_dummy_shared_info;
68 
69 __read_mostly int xen_have_vector_callback;
70 EXPORT_SYMBOL_GPL(xen_have_vector_callback);
71 
72 /*
73  * NB: These need to live in .data or alike because they're used by
74  * xen_prepare_pvh() which runs before clearing the bss.
75  */
76 enum xen_domain_type __ro_after_init xen_domain_type = XEN_NATIVE;
77 EXPORT_SYMBOL_GPL(xen_domain_type);
78 uint32_t __ro_after_init xen_start_flags;
79 EXPORT_SYMBOL(xen_start_flags);
80 
81 /*
82  * Point at some empty memory to start with. We map the real shared_info
83  * page as soon as fixmap is up and running.
84  */
85 struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info;
86 
87 /*
88  * Flag to determine whether vcpu info placement is available on all
89  * VCPUs.  We assume it is to start with, and then set it to zero on
90  * the first failure.  This is because it can succeed on some VCPUs
91  * and not others, since it can involve hypervisor memory allocation,
92  * or because the guest failed to guarantee all the appropriate
93  * constraints on all VCPUs (ie buffer can't cross a page boundary).
94  *
95  * Note that any particular CPU may be using a placed vcpu structure,
96  * but we can only optimise if the all are.
97  *
98  * 0: not available, 1: available
99  */
100 int xen_have_vcpu_info_placement = 1;
101 
xen_cpu_up_online(unsigned int cpu)102 static int xen_cpu_up_online(unsigned int cpu)
103 {
104 	xen_init_lock_cpu(cpu);
105 	return 0;
106 }
107 
xen_cpuhp_setup(int (* cpu_up_prepare_cb)(unsigned int),int (* cpu_dead_cb)(unsigned int))108 int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
109 		    int (*cpu_dead_cb)(unsigned int))
110 {
111 	int rc;
112 
113 	rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
114 				       "x86/xen/guest:prepare",
115 				       cpu_up_prepare_cb, cpu_dead_cb);
116 	if (rc >= 0) {
117 		rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
118 					       "x86/xen/guest:online",
119 					       xen_cpu_up_online, NULL);
120 		if (rc < 0)
121 			cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
122 	}
123 
124 	return rc >= 0 ? 0 : rc;
125 }
126 
xen_vcpu_setup_restore(int cpu)127 static int xen_vcpu_setup_restore(int cpu)
128 {
129 	int rc = 0;
130 
131 	/* Any per_cpu(xen_vcpu) is stale, so reset it */
132 	xen_vcpu_info_reset(cpu);
133 
134 	/*
135 	 * For PVH and PVHVM, setup online VCPUs only. The rest will
136 	 * be handled by hotplug.
137 	 */
138 	if (xen_pv_domain() ||
139 	    (xen_hvm_domain() && cpu_online(cpu))) {
140 		rc = xen_vcpu_setup(cpu);
141 	}
142 
143 	return rc;
144 }
145 
146 /*
147  * On restore, set the vcpu placement up again.
148  * If it fails, then we're in a bad state, since
149  * we can't back out from using it...
150  */
xen_vcpu_restore(void)151 void xen_vcpu_restore(void)
152 {
153 	int cpu, rc;
154 
155 	for_each_possible_cpu(cpu) {
156 		bool other_cpu = (cpu != smp_processor_id());
157 		bool is_up;
158 
159 		if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
160 			continue;
161 
162 		/* Only Xen 4.5 and higher support this. */
163 		is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
164 					   xen_vcpu_nr(cpu), NULL) > 0;
165 
166 		if (other_cpu && is_up &&
167 		    HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
168 			BUG();
169 
170 		if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
171 			xen_setup_runstate_info(cpu);
172 
173 		rc = xen_vcpu_setup_restore(cpu);
174 		if (rc)
175 			pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
176 					"System will hang.\n", cpu, rc);
177 		/*
178 		 * In case xen_vcpu_setup_restore() fails, do not bring up the
179 		 * VCPU. This helps us avoid the resulting OOPS when the VCPU
180 		 * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
181 		 * Note that this does not improve the situation much -- now the
182 		 * VM hangs instead of OOPSing -- with the VCPUs that did not
183 		 * fail, spinning in stop_machine(), waiting for the failed
184 		 * VCPUs to come up.
185 		 */
186 		if (other_cpu && is_up && (rc == 0) &&
187 		    HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
188 			BUG();
189 	}
190 }
191 
xen_vcpu_info_reset(int cpu)192 void xen_vcpu_info_reset(int cpu)
193 {
194 	if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
195 		per_cpu(xen_vcpu, cpu) =
196 			&HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
197 	} else {
198 		/* Set to NULL so that if somebody accesses it we get an OOPS */
199 		per_cpu(xen_vcpu, cpu) = NULL;
200 	}
201 }
202 
xen_vcpu_setup(int cpu)203 int xen_vcpu_setup(int cpu)
204 {
205 	struct vcpu_register_vcpu_info info;
206 	int err;
207 	struct vcpu_info *vcpup;
208 
209 	BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
210 
211 	/*
212 	 * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
213 	 * and at restore (xen_vcpu_restore). Also called for hotplugged
214 	 * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
215 	 * However, the hypercall can only be done once (see below) so if a VCPU
216 	 * is offlined and comes back online then let's not redo the hypercall.
217 	 *
218 	 * For PV it is called during restore (xen_vcpu_restore) and bootup
219 	 * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
220 	 * use this function.
221 	 */
222 	if (xen_hvm_domain()) {
223 		if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
224 			return 0;
225 	}
226 
227 	if (xen_have_vcpu_info_placement) {
228 		vcpup = &per_cpu(xen_vcpu_info, cpu);
229 		info.mfn = arbitrary_virt_to_mfn(vcpup);
230 		info.offset = offset_in_page(vcpup);
231 
232 		/*
233 		 * Check to see if the hypervisor will put the vcpu_info
234 		 * structure where we want it, which allows direct access via
235 		 * a percpu-variable.
236 		 * N.B. This hypercall can _only_ be called once per CPU.
237 		 * Subsequent calls will error out with -EINVAL. This is due to
238 		 * the fact that hypervisor has no unregister variant and this
239 		 * hypercall does not allow to over-write info.mfn and
240 		 * info.offset.
241 		 */
242 		err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
243 					 xen_vcpu_nr(cpu), &info);
244 
245 		if (err) {
246 			pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
247 				     cpu, err);
248 			xen_have_vcpu_info_placement = 0;
249 		} else {
250 			/*
251 			 * This cpu is using the registered vcpu info, even if
252 			 * later ones fail to.
253 			 */
254 			per_cpu(xen_vcpu, cpu) = vcpup;
255 		}
256 	}
257 
258 	if (!xen_have_vcpu_info_placement)
259 		xen_vcpu_info_reset(cpu);
260 
261 	return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
262 }
263 
xen_banner(void)264 void __init xen_banner(void)
265 {
266 	unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
267 	struct xen_extraversion extra;
268 
269 	HYPERVISOR_xen_version(XENVER_extraversion, &extra);
270 
271 	pr_info("Booting kernel on %s\n", pv_info.name);
272 	pr_info("Xen version: %u.%u%s%s\n",
273 		version >> 16, version & 0xffff, extra.extraversion,
274 		xen_feature(XENFEAT_mmu_pt_update_preserve_ad)
275 		? " (preserve-AD)" : "");
276 }
277 
278 /* Check if running on Xen version (major, minor) or later */
xen_running_on_version_or_later(unsigned int major,unsigned int minor)279 bool xen_running_on_version_or_later(unsigned int major, unsigned int minor)
280 {
281 	unsigned int version;
282 
283 	if (!xen_domain())
284 		return false;
285 
286 	version = HYPERVISOR_xen_version(XENVER_version, NULL);
287 	if ((((version >> 16) == major) && ((version & 0xffff) >= minor)) ||
288 		((version >> 16) > major))
289 		return true;
290 	return false;
291 }
292 
xen_add_preferred_consoles(void)293 void __init xen_add_preferred_consoles(void)
294 {
295 	add_preferred_console("xenboot", 0, NULL);
296 	if (!boot_params.screen_info.orig_video_isVGA)
297 		add_preferred_console("tty", 0, NULL);
298 	add_preferred_console("hvc", 0, NULL);
299 	if (boot_params.screen_info.orig_video_isVGA)
300 		add_preferred_console("tty", 0, NULL);
301 }
302 
xen_reboot(int reason)303 void xen_reboot(int reason)
304 {
305 	struct sched_shutdown r = { .reason = reason };
306 	int cpu;
307 
308 	for_each_online_cpu(cpu)
309 		xen_pmu_finish(cpu);
310 
311 	if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
312 		BUG();
313 }
314 
315 static int reboot_reason = SHUTDOWN_reboot;
316 static bool xen_legacy_crash;
xen_emergency_restart(void)317 void xen_emergency_restart(void)
318 {
319 	xen_reboot(reboot_reason);
320 }
321 
322 static int
xen_panic_event(struct notifier_block * this,unsigned long event,void * ptr)323 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
324 {
325 	if (!kexec_crash_loaded()) {
326 		if (xen_legacy_crash)
327 			xen_reboot(SHUTDOWN_crash);
328 
329 		reboot_reason = SHUTDOWN_crash;
330 
331 		/*
332 		 * If panic_timeout==0 then we are supposed to wait forever.
333 		 * However, to preserve original dom0 behavior we have to drop
334 		 * into hypervisor. (domU behavior is controlled by its
335 		 * config file)
336 		 */
337 		if (panic_timeout == 0)
338 			panic_timeout = -1;
339 	}
340 	return NOTIFY_DONE;
341 }
342 
parse_xen_legacy_crash(char * arg)343 static int __init parse_xen_legacy_crash(char *arg)
344 {
345 	xen_legacy_crash = true;
346 	return 0;
347 }
348 early_param("xen_legacy_crash", parse_xen_legacy_crash);
349 
350 static struct notifier_block xen_panic_block = {
351 	.notifier_call = xen_panic_event,
352 	.priority = INT_MIN
353 };
354 
xen_panic_handler_init(void)355 int xen_panic_handler_init(void)
356 {
357 	atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
358 	return 0;
359 }
360 
xen_pin_vcpu(int cpu)361 void xen_pin_vcpu(int cpu)
362 {
363 	static bool disable_pinning;
364 	struct sched_pin_override pin_override;
365 	int ret;
366 
367 	if (disable_pinning)
368 		return;
369 
370 	pin_override.pcpu = cpu;
371 	ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
372 
373 	/* Ignore errors when removing override. */
374 	if (cpu < 0)
375 		return;
376 
377 	switch (ret) {
378 	case -ENOSYS:
379 		pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
380 			cpu);
381 		disable_pinning = true;
382 		break;
383 	case -EPERM:
384 		WARN(1, "Trying to pin vcpu without having privilege to do so\n");
385 		disable_pinning = true;
386 		break;
387 	case -EINVAL:
388 	case -EBUSY:
389 		pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
390 			cpu);
391 		break;
392 	case 0:
393 		break;
394 	default:
395 		WARN(1, "rc %d while trying to pin vcpu\n", ret);
396 		disable_pinning = true;
397 	}
398 }
399 
400 #ifdef CONFIG_HOTPLUG_CPU
xen_arch_register_cpu(int num)401 void xen_arch_register_cpu(int num)
402 {
403 	arch_register_cpu(num);
404 }
405 EXPORT_SYMBOL(xen_arch_register_cpu);
406 
xen_arch_unregister_cpu(int num)407 void xen_arch_unregister_cpu(int num)
408 {
409 	arch_unregister_cpu(num);
410 }
411 EXPORT_SYMBOL(xen_arch_unregister_cpu);
412 #endif
413