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