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Linux/drivers/xen/xen-acpi-cpuhotplug.c

  1 /*
  2  * Copyright (C) 2012 Intel Corporation
  3  *    Author: Liu Jinsong <jinsong.liu@intel.com>
  4  *    Author: Jiang Yunhong <yunhong.jiang@intel.com>
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or (at
  9  * your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful, but
 12  * WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 14  * NON INFRINGEMENT.  See the GNU General Public License for more
 15  * details.
 16  */
 17 
 18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 19 
 20 #include <linux/kernel.h>
 21 #include <linux/module.h>
 22 #include <linux/init.h>
 23 #include <linux/types.h>
 24 #include <linux/cpu.h>
 25 #include <linux/acpi.h>
 26 #include <linux/uaccess.h>
 27 #include <acpi/processor.h>
 28 #include <xen/acpi.h>
 29 #include <xen/interface/platform.h>
 30 #include <asm/xen/hypercall.h>
 31 
 32 #define PREFIX "ACPI:xen_cpu_hotplug:"
 33 
 34 #define INSTALL_NOTIFY_HANDLER          0
 35 #define UNINSTALL_NOTIFY_HANDLER        1
 36 
 37 static acpi_status xen_acpi_cpu_hotadd(struct acpi_processor *pr);
 38 
 39 /* --------------------------------------------------------------------------
 40                                 Driver Interface
 41 -------------------------------------------------------------------------- */
 42 
 43 static int xen_acpi_processor_enable(struct acpi_device *device)
 44 {
 45         acpi_status status = 0;
 46         unsigned long long value;
 47         union acpi_object object = { 0 };
 48         struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
 49         struct acpi_processor *pr = acpi_driver_data(device);
 50 
 51         if (!strcmp(acpi_device_hid(device), ACPI_PROCESSOR_OBJECT_HID)) {
 52                 /* Declared with "Processor" statement; match ProcessorID */
 53                 status = acpi_evaluate_object(pr->handle, NULL, NULL, &buffer);
 54                 if (ACPI_FAILURE(status)) {
 55                         pr_err(PREFIX "Evaluating processor object\n");
 56                         return -ENODEV;
 57                 }
 58 
 59                 pr->acpi_id = object.processor.proc_id;
 60         } else {
 61                 /* Declared with "Device" statement; match _UID */
 62                 status = acpi_evaluate_integer(pr->handle, METHOD_NAME__UID,
 63                                                 NULL, &value);
 64                 if (ACPI_FAILURE(status)) {
 65                         pr_err(PREFIX "Evaluating processor _UID\n");
 66                         return -ENODEV;
 67                 }
 68 
 69                 pr->acpi_id = value;
 70         }
 71 
 72         pr->id = xen_pcpu_id(pr->acpi_id);
 73 
 74         if (invalid_logical_cpuid(pr->id))
 75                 /* This cpu is not presented at hypervisor, try to hotadd it */
 76                 if (ACPI_FAILURE(xen_acpi_cpu_hotadd(pr))) {
 77                         pr_err(PREFIX "Hotadd CPU (acpi_id = %d) failed.\n",
 78                                         pr->acpi_id);
 79                         return -ENODEV;
 80                 }
 81 
 82         return 0;
 83 }
 84 
 85 static int xen_acpi_processor_add(struct acpi_device *device)
 86 {
 87         int ret;
 88         struct acpi_processor *pr;
 89 
 90         if (!device)
 91                 return -EINVAL;
 92 
 93         pr = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
 94         if (!pr)
 95                 return -ENOMEM;
 96 
 97         pr->handle = device->handle;
 98         strcpy(acpi_device_name(device), ACPI_PROCESSOR_DEVICE_NAME);
 99         strcpy(acpi_device_class(device), ACPI_PROCESSOR_CLASS);
100         device->driver_data = pr;
101 
102         ret = xen_acpi_processor_enable(device);
103         if (ret)
104                 pr_err(PREFIX "Error when enabling Xen processor\n");
105 
106         return ret;
107 }
108 
109 static int xen_acpi_processor_remove(struct acpi_device *device)
110 {
111         struct acpi_processor *pr;
112 
113         if (!device)
114                 return -EINVAL;
115 
116         pr = acpi_driver_data(device);
117         if (!pr)
118                 return -EINVAL;
119 
120         kfree(pr);
121         return 0;
122 }
123 
124 /*--------------------------------------------------------------
125                 Acpi processor hotplug support
126 --------------------------------------------------------------*/
127 
128 static int is_processor_present(acpi_handle handle)
129 {
130         acpi_status status;
131         unsigned long long sta = 0;
132 
133 
134         status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
135 
136         if (ACPI_SUCCESS(status) && (sta & ACPI_STA_DEVICE_PRESENT))
137                 return 1;
138 
139         /*
140          * _STA is mandatory for a processor that supports hot plug
141          */
142         if (status == AE_NOT_FOUND)
143                 pr_info(PREFIX "Processor does not support hot plug\n");
144         else
145                 pr_info(PREFIX "Processor Device is not present");
146         return 0;
147 }
148 
149 static int xen_apic_id(acpi_handle handle)
150 {
151         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
152         union acpi_object *obj;
153         struct acpi_madt_local_apic *lapic;
154         int apic_id;
155 
156         if (ACPI_FAILURE(acpi_evaluate_object(handle, "_MAT", NULL, &buffer)))
157                 return -EINVAL;
158 
159         if (!buffer.length || !buffer.pointer)
160                 return -EINVAL;
161 
162         obj = buffer.pointer;
163         if (obj->type != ACPI_TYPE_BUFFER ||
164             obj->buffer.length < sizeof(*lapic)) {
165                 kfree(buffer.pointer);
166                 return -EINVAL;
167         }
168 
169         lapic = (struct acpi_madt_local_apic *)obj->buffer.pointer;
170 
171         if (lapic->header.type != ACPI_MADT_TYPE_LOCAL_APIC ||
172             !(lapic->lapic_flags & ACPI_MADT_ENABLED)) {
173                 kfree(buffer.pointer);
174                 return -EINVAL;
175         }
176 
177         apic_id = (uint32_t)lapic->id;
178         kfree(buffer.pointer);
179         buffer.length = ACPI_ALLOCATE_BUFFER;
180         buffer.pointer = NULL;
181 
182         return apic_id;
183 }
184 
185 static int xen_hotadd_cpu(struct acpi_processor *pr)
186 {
187         int cpu_id, apic_id, pxm;
188         struct xen_platform_op op;
189 
190         apic_id = xen_apic_id(pr->handle);
191         if (apic_id < 0) {
192                 pr_err(PREFIX "Failed to get apic_id for acpi_id %d\n",
193                                 pr->acpi_id);
194                 return -ENODEV;
195         }
196 
197         pxm = xen_acpi_get_pxm(pr->handle);
198         if (pxm < 0) {
199                 pr_err(PREFIX "Failed to get _PXM for acpi_id %d\n",
200                                 pr->acpi_id);
201                 return pxm;
202         }
203 
204         op.cmd = XENPF_cpu_hotadd;
205         op.u.cpu_add.apic_id = apic_id;
206         op.u.cpu_add.acpi_id = pr->acpi_id;
207         op.u.cpu_add.pxm = pxm;
208 
209         cpu_id = HYPERVISOR_platform_op(&op);
210         if (cpu_id < 0)
211                 pr_err(PREFIX "Failed to hotadd CPU for acpi_id %d\n",
212                                 pr->acpi_id);
213 
214         return cpu_id;
215 }
216 
217 static acpi_status xen_acpi_cpu_hotadd(struct acpi_processor *pr)
218 {
219         if (!is_processor_present(pr->handle))
220                 return AE_ERROR;
221 
222         pr->id = xen_hotadd_cpu(pr);
223         if (invalid_logical_cpuid(pr->id))
224                 return AE_ERROR;
225 
226         /*
227          * Sync with Xen hypervisor, providing new /sys/.../xen_cpuX
228          * interface after cpu hotadded.
229          */
230         xen_pcpu_hotplug_sync();
231 
232         return AE_OK;
233 }
234 
235 static int acpi_processor_device_remove(struct acpi_device *device)
236 {
237         pr_debug(PREFIX "Xen does not support CPU hotremove\n");
238 
239         return -ENOSYS;
240 }
241 
242 static void acpi_processor_hotplug_notify(acpi_handle handle,
243                                           u32 event, void *data)
244 {
245         struct acpi_processor *pr;
246         struct acpi_device *device = NULL;
247         u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
248         int result;
249 
250         acpi_scan_lock_acquire();
251 
252         switch (event) {
253         case ACPI_NOTIFY_BUS_CHECK:
254         case ACPI_NOTIFY_DEVICE_CHECK:
255                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
256                         "Processor driver received %s event\n",
257                         (event == ACPI_NOTIFY_BUS_CHECK) ?
258                         "ACPI_NOTIFY_BUS_CHECK" : "ACPI_NOTIFY_DEVICE_CHECK"));
259 
260                 if (!is_processor_present(handle))
261                         break;
262 
263                 acpi_bus_get_device(handle, &device);
264                 if (acpi_device_enumerated(device))
265                         break;
266 
267                 result = acpi_bus_scan(handle);
268                 if (result) {
269                         pr_err(PREFIX "Unable to add the device\n");
270                         break;
271                 }
272                 device = NULL;
273                 acpi_bus_get_device(handle, &device);
274                 if (!acpi_device_enumerated(device)) {
275                         pr_err(PREFIX "Missing device object\n");
276                         break;
277                 }
278                 ost_code = ACPI_OST_SC_SUCCESS;
279                 break;
280 
281         case ACPI_NOTIFY_EJECT_REQUEST:
282                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
283                                   "received ACPI_NOTIFY_EJECT_REQUEST\n"));
284 
285                 if (acpi_bus_get_device(handle, &device)) {
286                         pr_err(PREFIX "Device don't exist, dropping EJECT\n");
287                         break;
288                 }
289                 pr = acpi_driver_data(device);
290                 if (!pr) {
291                         pr_err(PREFIX "Driver data is NULL, dropping EJECT\n");
292                         break;
293                 }
294 
295                 /*
296                  * TBD: implement acpi_processor_device_remove if Xen support
297                  * CPU hotremove in the future.
298                  */
299                 acpi_processor_device_remove(device);
300                 break;
301 
302         default:
303                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
304                                   "Unsupported event [0x%x]\n", event));
305 
306                 /* non-hotplug event; possibly handled by other handler */
307                 goto out;
308         }
309 
310         (void) acpi_evaluate_ost(handle, event, ost_code, NULL);
311 
312 out:
313         acpi_scan_lock_release();
314 }
315 
316 static acpi_status is_processor_device(acpi_handle handle)
317 {
318         struct acpi_device_info *info;
319         char *hid;
320         acpi_status status;
321 
322         status = acpi_get_object_info(handle, &info);
323         if (ACPI_FAILURE(status))
324                 return status;
325 
326         if (info->type == ACPI_TYPE_PROCESSOR) {
327                 kfree(info);
328                 return AE_OK;   /* found a processor object */
329         }
330 
331         if (!(info->valid & ACPI_VALID_HID)) {
332                 kfree(info);
333                 return AE_ERROR;
334         }
335 
336         hid = info->hardware_id.string;
337         if ((hid == NULL) || strcmp(hid, ACPI_PROCESSOR_DEVICE_HID)) {
338                 kfree(info);
339                 return AE_ERROR;
340         }
341 
342         kfree(info);
343         return AE_OK;   /* found a processor device object */
344 }
345 
346 static acpi_status
347 processor_walk_namespace_cb(acpi_handle handle,
348                             u32 lvl, void *context, void **rv)
349 {
350         acpi_status status;
351         int *action = context;
352 
353         status = is_processor_device(handle);
354         if (ACPI_FAILURE(status))
355                 return AE_OK;   /* not a processor; continue to walk */
356 
357         switch (*action) {
358         case INSTALL_NOTIFY_HANDLER:
359                 acpi_install_notify_handler(handle,
360                                             ACPI_SYSTEM_NOTIFY,
361                                             acpi_processor_hotplug_notify,
362                                             NULL);
363                 break;
364         case UNINSTALL_NOTIFY_HANDLER:
365                 acpi_remove_notify_handler(handle,
366                                            ACPI_SYSTEM_NOTIFY,
367                                            acpi_processor_hotplug_notify);
368                 break;
369         default:
370                 break;
371         }
372 
373         /* found a processor; skip walking underneath */
374         return AE_CTRL_DEPTH;
375 }
376 
377 static
378 void acpi_processor_install_hotplug_notify(void)
379 {
380         int action = INSTALL_NOTIFY_HANDLER;
381         acpi_walk_namespace(ACPI_TYPE_ANY,
382                             ACPI_ROOT_OBJECT,
383                             ACPI_UINT32_MAX,
384                             processor_walk_namespace_cb, NULL, &action, NULL);
385 }
386 
387 static
388 void acpi_processor_uninstall_hotplug_notify(void)
389 {
390         int action = UNINSTALL_NOTIFY_HANDLER;
391         acpi_walk_namespace(ACPI_TYPE_ANY,
392                             ACPI_ROOT_OBJECT,
393                             ACPI_UINT32_MAX,
394                             processor_walk_namespace_cb, NULL, &action, NULL);
395 }
396 
397 static const struct acpi_device_id processor_device_ids[] = {
398         {ACPI_PROCESSOR_OBJECT_HID, 0},
399         {ACPI_PROCESSOR_DEVICE_HID, 0},
400         {"", 0},
401 };
402 MODULE_DEVICE_TABLE(acpi, processor_device_ids);
403 
404 static struct acpi_driver xen_acpi_processor_driver = {
405         .name = "processor",
406         .class = ACPI_PROCESSOR_CLASS,
407         .ids = processor_device_ids,
408         .ops = {
409                 .add = xen_acpi_processor_add,
410                 .remove = xen_acpi_processor_remove,
411                 },
412 };
413 
414 static int __init xen_acpi_processor_init(void)
415 {
416         int result = 0;
417 
418         if (!xen_initial_domain())
419                 return -ENODEV;
420 
421         /* unregister the stub which only used to reserve driver space */
422         xen_stub_processor_exit();
423 
424         result = acpi_bus_register_driver(&xen_acpi_processor_driver);
425         if (result < 0) {
426                 xen_stub_processor_init();
427                 return result;
428         }
429 
430         acpi_processor_install_hotplug_notify();
431         return 0;
432 }
433 
434 static void __exit xen_acpi_processor_exit(void)
435 {
436         if (!xen_initial_domain())
437                 return;
438 
439         acpi_processor_uninstall_hotplug_notify();
440 
441         acpi_bus_unregister_driver(&xen_acpi_processor_driver);
442 
443         /*
444          * stub reserve space again to prevent any chance of native
445          * driver loading.
446          */
447         xen_stub_processor_init();
448         return;
449 }
450 
451 module_init(xen_acpi_processor_init);
452 module_exit(xen_acpi_processor_exit);
453 ACPI_MODULE_NAME("xen-acpi-cpuhotplug");
454 MODULE_AUTHOR("Liu Jinsong <jinsong.liu@intel.com>");
455 MODULE_DESCRIPTION("Xen Hotplug CPU Driver");
456 MODULE_LICENSE("GPL");
457 

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