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