Merge tag 'for-linus-4.20a-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel...
[muen/linux.git] / arch / x86 / xen / enlighten.c
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 enum xen_domain_type xen_domain_type = XEN_NATIVE;
55 EXPORT_SYMBOL_GPL(xen_domain_type);
56
57 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
58 EXPORT_SYMBOL(machine_to_phys_mapping);
59 unsigned long  machine_to_phys_nr;
60 EXPORT_SYMBOL(machine_to_phys_nr);
61
62 struct start_info *xen_start_info;
63 EXPORT_SYMBOL_GPL(xen_start_info);
64
65 struct shared_info xen_dummy_shared_info;
66
67 __read_mostly int xen_have_vector_callback;
68 EXPORT_SYMBOL_GPL(xen_have_vector_callback);
69
70 /*
71  * NB: needs to live in .data because it's used by xen_prepare_pvh which runs
72  * before clearing the bss.
73  */
74 uint32_t xen_start_flags __attribute__((section(".data"))) = 0;
75 EXPORT_SYMBOL(xen_start_flags);
76
77 /*
78  * Point at some empty memory to start with. We map the real shared_info
79  * page as soon as fixmap is up and running.
80  */
81 struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info;
82
83 /*
84  * Flag to determine whether vcpu info placement is available on all
85  * VCPUs.  We assume it is to start with, and then set it to zero on
86  * the first failure.  This is because it can succeed on some VCPUs
87  * and not others, since it can involve hypervisor memory allocation,
88  * or because the guest failed to guarantee all the appropriate
89  * constraints on all VCPUs (ie buffer can't cross a page boundary).
90  *
91  * Note that any particular CPU may be using a placed vcpu structure,
92  * but we can only optimise if the all are.
93  *
94  * 0: not available, 1: available
95  */
96 int xen_have_vcpu_info_placement = 1;
97
98 static int xen_cpu_up_online(unsigned int cpu)
99 {
100         xen_init_lock_cpu(cpu);
101         return 0;
102 }
103
104 int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
105                     int (*cpu_dead_cb)(unsigned int))
106 {
107         int rc;
108
109         rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
110                                        "x86/xen/guest:prepare",
111                                        cpu_up_prepare_cb, cpu_dead_cb);
112         if (rc >= 0) {
113                 rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
114                                                "x86/xen/guest:online",
115                                                xen_cpu_up_online, NULL);
116                 if (rc < 0)
117                         cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
118         }
119
120         return rc >= 0 ? 0 : rc;
121 }
122
123 static int xen_vcpu_setup_restore(int cpu)
124 {
125         int rc = 0;
126
127         /* Any per_cpu(xen_vcpu) is stale, so reset it */
128         xen_vcpu_info_reset(cpu);
129
130         /*
131          * For PVH and PVHVM, setup online VCPUs only. The rest will
132          * be handled by hotplug.
133          */
134         if (xen_pv_domain() ||
135             (xen_hvm_domain() && cpu_online(cpu))) {
136                 rc = xen_vcpu_setup(cpu);
137         }
138
139         return rc;
140 }
141
142 /*
143  * On restore, set the vcpu placement up again.
144  * If it fails, then we're in a bad state, since
145  * we can't back out from using it...
146  */
147 void xen_vcpu_restore(void)
148 {
149         int cpu, rc;
150
151         for_each_possible_cpu(cpu) {
152                 bool other_cpu = (cpu != smp_processor_id());
153                 bool is_up;
154
155                 if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
156                         continue;
157
158                 /* Only Xen 4.5 and higher support this. */
159                 is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
160                                            xen_vcpu_nr(cpu), NULL) > 0;
161
162                 if (other_cpu && is_up &&
163                     HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
164                         BUG();
165
166                 if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
167                         xen_setup_runstate_info(cpu);
168
169                 rc = xen_vcpu_setup_restore(cpu);
170                 if (rc)
171                         pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
172                                         "System will hang.\n", cpu, rc);
173                 /*
174                  * In case xen_vcpu_setup_restore() fails, do not bring up the
175                  * VCPU. This helps us avoid the resulting OOPS when the VCPU
176                  * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
177                  * Note that this does not improve the situation much -- now the
178                  * VM hangs instead of OOPSing -- with the VCPUs that did not
179                  * fail, spinning in stop_machine(), waiting for the failed
180                  * VCPUs to come up.
181                  */
182                 if (other_cpu && is_up && (rc == 0) &&
183                     HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
184                         BUG();
185         }
186 }
187
188 void xen_vcpu_info_reset(int cpu)
189 {
190         if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
191                 per_cpu(xen_vcpu, cpu) =
192                         &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
193         } else {
194                 /* Set to NULL so that if somebody accesses it we get an OOPS */
195                 per_cpu(xen_vcpu, cpu) = NULL;
196         }
197 }
198
199 int xen_vcpu_setup(int cpu)
200 {
201         struct vcpu_register_vcpu_info info;
202         int err;
203         struct vcpu_info *vcpup;
204
205         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
206
207         /*
208          * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
209          * and at restore (xen_vcpu_restore). Also called for hotplugged
210          * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
211          * However, the hypercall can only be done once (see below) so if a VCPU
212          * is offlined and comes back online then let's not redo the hypercall.
213          *
214          * For PV it is called during restore (xen_vcpu_restore) and bootup
215          * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
216          * use this function.
217          */
218         if (xen_hvm_domain()) {
219                 if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
220                         return 0;
221         }
222
223         if (xen_have_vcpu_info_placement) {
224                 vcpup = &per_cpu(xen_vcpu_info, cpu);
225                 info.mfn = arbitrary_virt_to_mfn(vcpup);
226                 info.offset = offset_in_page(vcpup);
227
228                 /*
229                  * Check to see if the hypervisor will put the vcpu_info
230                  * structure where we want it, which allows direct access via
231                  * a percpu-variable.
232                  * N.B. This hypercall can _only_ be called once per CPU.
233                  * Subsequent calls will error out with -EINVAL. This is due to
234                  * the fact that hypervisor has no unregister variant and this
235                  * hypercall does not allow to over-write info.mfn and
236                  * info.offset.
237                  */
238                 err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
239                                          xen_vcpu_nr(cpu), &info);
240
241                 if (err) {
242                         pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
243                                      cpu, err);
244                         xen_have_vcpu_info_placement = 0;
245                 } else {
246                         /*
247                          * This cpu is using the registered vcpu info, even if
248                          * later ones fail to.
249                          */
250                         per_cpu(xen_vcpu, cpu) = vcpup;
251                 }
252         }
253
254         if (!xen_have_vcpu_info_placement)
255                 xen_vcpu_info_reset(cpu);
256
257         return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
258 }
259
260 void xen_reboot(int reason)
261 {
262         struct sched_shutdown r = { .reason = reason };
263         int cpu;
264
265         for_each_online_cpu(cpu)
266                 xen_pmu_finish(cpu);
267
268         if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
269                 BUG();
270 }
271
272 void xen_emergency_restart(void)
273 {
274         xen_reboot(SHUTDOWN_reboot);
275 }
276
277 static int
278 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
279 {
280         if (!kexec_crash_loaded())
281                 xen_reboot(SHUTDOWN_crash);
282         return NOTIFY_DONE;
283 }
284
285 static struct notifier_block xen_panic_block = {
286         .notifier_call = xen_panic_event,
287         .priority = INT_MIN
288 };
289
290 int xen_panic_handler_init(void)
291 {
292         atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
293         return 0;
294 }
295
296 void xen_pin_vcpu(int cpu)
297 {
298         static bool disable_pinning;
299         struct sched_pin_override pin_override;
300         int ret;
301
302         if (disable_pinning)
303                 return;
304
305         pin_override.pcpu = cpu;
306         ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
307
308         /* Ignore errors when removing override. */
309         if (cpu < 0)
310                 return;
311
312         switch (ret) {
313         case -ENOSYS:
314                 pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
315                         cpu);
316                 disable_pinning = true;
317                 break;
318         case -EPERM:
319                 WARN(1, "Trying to pin vcpu without having privilege to do so\n");
320                 disable_pinning = true;
321                 break;
322         case -EINVAL:
323         case -EBUSY:
324                 pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
325                         cpu);
326                 break;
327         case 0:
328                 break;
329         default:
330                 WARN(1, "rc %d while trying to pin vcpu\n", ret);
331                 disable_pinning = true;
332         }
333 }
334
335 #ifdef CONFIG_HOTPLUG_CPU
336 void xen_arch_register_cpu(int num)
337 {
338         arch_register_cpu(num);
339 }
340 EXPORT_SYMBOL(xen_arch_register_cpu);
341
342 void xen_arch_unregister_cpu(int num)
343 {
344         arch_unregister_cpu(num);
345 }
346 EXPORT_SYMBOL(xen_arch_unregister_cpu);
347 #endif