1 /****************************************************************************** 2 * pcpu.c 3 * Management physical cpu in dom0, get pcpu info and provide sys interface 4 * 5 * Copyright (c) 2012 Intel Corporation 6 * Author: Liu, Jinsong <jinsong.liu@intel.com> 7 * Author: Jiang, Yunhong <yunhong.jiang@intel.com> 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License version 2 11 * as published by the Free Software Foundation; or, when distributed 12 * separately from the Linux kernel or incorporated into other 13 * software packages, subject to the following license: 14 * 15 * Permission is hereby granted, free of charge, to any person obtaining a copy 16 * of this source file (the "Software"), to deal in the Software without 17 * restriction, including without limitation the rights to use, copy, modify, 18 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 19 * and to permit persons to whom the Software is furnished to do so, subject to 20 * the following conditions: 21 * 22 * The above copyright notice and this permission notice shall be included in 23 * all copies or substantial portions of the Software. 24 * 25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 31 * IN THE SOFTWARE. 32 */ 33 34 #define pr_fmt(fmt) "xen_cpu: " fmt 35 36 #include <linux/interrupt.h> 37 #include <linux/spinlock.h> 38 #include <linux/cpu.h> 39 #include <linux/stat.h> 40 #include <linux/capability.h> 41 42 #include <xen/xen.h> 43 #include <xen/acpi.h> 44 #include <xen/xenbus.h> 45 #include <xen/events.h> 46 #include <xen/interface/platform.h> 47 #include <asm/xen/hypervisor.h> 48 #include <asm/xen/hypercall.h> 49 50 #ifdef CONFIG_ACPI 51 #include <acpi/processor.h> 52 #endif 53 54 /* 55 * @cpu_id: Xen physical cpu logic number 56 * @flags: Xen physical cpu status flag 57 * - XEN_PCPU_FLAGS_ONLINE: cpu is online 58 * - XEN_PCPU_FLAGS_INVALID: cpu is not present 59 */ 60 struct pcpu { 61 struct list_head list; 62 struct device dev; 63 uint32_t cpu_id; 64 uint32_t acpi_id; 65 uint32_t flags; 66 }; 67 68 static struct bus_type xen_pcpu_subsys = { 69 .name = "xen_cpu", 70 .dev_name = "xen_cpu", 71 }; 72 73 static DEFINE_MUTEX(xen_pcpu_lock); 74 75 static LIST_HEAD(xen_pcpus); 76 77 static int xen_pcpu_down(uint32_t cpu_id) 78 { 79 struct xen_platform_op op = { 80 .cmd = XENPF_cpu_offline, 81 .interface_version = XENPF_INTERFACE_VERSION, 82 .u.cpu_ol.cpuid = cpu_id, 83 }; 84 85 return HYPERVISOR_platform_op(&op); 86 } 87 88 static int xen_pcpu_up(uint32_t cpu_id) 89 { 90 struct xen_platform_op op = { 91 .cmd = XENPF_cpu_online, 92 .interface_version = XENPF_INTERFACE_VERSION, 93 .u.cpu_ol.cpuid = cpu_id, 94 }; 95 96 return HYPERVISOR_platform_op(&op); 97 } 98 99 static ssize_t online_show(struct device *dev, 100 struct device_attribute *attr, 101 char *buf) 102 { 103 struct pcpu *cpu = container_of(dev, struct pcpu, dev); 104 105 return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE)); 106 } 107 108 static ssize_t __ref online_store(struct device *dev, 109 struct device_attribute *attr, 110 const char *buf, size_t count) 111 { 112 struct pcpu *pcpu = container_of(dev, struct pcpu, dev); 113 unsigned long long val; 114 ssize_t ret; 115 116 if (!capable(CAP_SYS_ADMIN)) 117 return -EPERM; 118 119 if (kstrtoull(buf, 0, &val) < 0) 120 return -EINVAL; 121 122 switch (val) { 123 case 0: 124 ret = xen_pcpu_down(pcpu->cpu_id); 125 break; 126 case 1: 127 ret = xen_pcpu_up(pcpu->cpu_id); 128 break; 129 default: 130 ret = -EINVAL; 131 } 132 133 if (ret >= 0) 134 ret = count; 135 return ret; 136 } 137 static DEVICE_ATTR_RW(online); 138 139 static struct attribute *pcpu_dev_attrs[] = { 140 &dev_attr_online.attr, 141 NULL 142 }; 143 144 static umode_t pcpu_dev_is_visible(struct kobject *kobj, 145 struct attribute *attr, int idx) 146 { 147 struct device *dev = kobj_to_dev(kobj); 148 /* 149 * Xen never offline cpu0 due to several restrictions 150 * and assumptions. This basically doesn't add a sys control 151 * to user, one cannot attempt to offline BSP. 152 */ 153 return dev->id ? attr->mode : 0; 154 } 155 156 static const struct attribute_group pcpu_dev_group = { 157 .attrs = pcpu_dev_attrs, 158 .is_visible = pcpu_dev_is_visible, 159 }; 160 161 static const struct attribute_group *pcpu_dev_groups[] = { 162 &pcpu_dev_group, 163 NULL 164 }; 165 166 static bool xen_pcpu_online(uint32_t flags) 167 { 168 return !!(flags & XEN_PCPU_FLAGS_ONLINE); 169 } 170 171 static void pcpu_online_status(struct xenpf_pcpuinfo *info, 172 struct pcpu *pcpu) 173 { 174 if (xen_pcpu_online(info->flags) && 175 !xen_pcpu_online(pcpu->flags)) { 176 /* the pcpu is onlined */ 177 pcpu->flags |= XEN_PCPU_FLAGS_ONLINE; 178 kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE); 179 } else if (!xen_pcpu_online(info->flags) && 180 xen_pcpu_online(pcpu->flags)) { 181 /* The pcpu is offlined */ 182 pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE; 183 kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE); 184 } 185 } 186 187 static struct pcpu *get_pcpu(uint32_t cpu_id) 188 { 189 struct pcpu *pcpu; 190 191 list_for_each_entry(pcpu, &xen_pcpus, list) { 192 if (pcpu->cpu_id == cpu_id) 193 return pcpu; 194 } 195 196 return NULL; 197 } 198 199 static void pcpu_release(struct device *dev) 200 { 201 struct pcpu *pcpu = container_of(dev, struct pcpu, dev); 202 203 list_del(&pcpu->list); 204 kfree(pcpu); 205 } 206 207 static void unregister_and_remove_pcpu(struct pcpu *pcpu) 208 { 209 struct device *dev; 210 211 if (!pcpu) 212 return; 213 214 dev = &pcpu->dev; 215 /* pcpu remove would be implicitly done */ 216 device_unregister(dev); 217 } 218 219 static int register_pcpu(struct pcpu *pcpu) 220 { 221 struct device *dev; 222 int err = -EINVAL; 223 224 if (!pcpu) 225 return err; 226 227 dev = &pcpu->dev; 228 dev->bus = &xen_pcpu_subsys; 229 dev->id = pcpu->cpu_id; 230 dev->release = pcpu_release; 231 dev->groups = pcpu_dev_groups; 232 233 err = device_register(dev); 234 if (err) { 235 put_device(dev); 236 return err; 237 } 238 239 return 0; 240 } 241 242 static struct pcpu *create_and_register_pcpu(struct xenpf_pcpuinfo *info) 243 { 244 struct pcpu *pcpu; 245 int err; 246 247 if (info->flags & XEN_PCPU_FLAGS_INVALID) 248 return ERR_PTR(-ENODEV); 249 250 pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL); 251 if (!pcpu) 252 return ERR_PTR(-ENOMEM); 253 254 INIT_LIST_HEAD(&pcpu->list); 255 pcpu->cpu_id = info->xen_cpuid; 256 pcpu->acpi_id = info->acpi_id; 257 pcpu->flags = info->flags; 258 259 /* Need hold on xen_pcpu_lock before pcpu list manipulations */ 260 list_add_tail(&pcpu->list, &xen_pcpus); 261 262 err = register_pcpu(pcpu); 263 if (err) { 264 pr_warn("Failed to register pcpu%u\n", info->xen_cpuid); 265 return ERR_PTR(-ENOENT); 266 } 267 268 return pcpu; 269 } 270 271 /* 272 * Caller should hold the xen_pcpu_lock 273 */ 274 static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu) 275 { 276 int ret; 277 struct pcpu *pcpu = NULL; 278 struct xenpf_pcpuinfo *info; 279 struct xen_platform_op op = { 280 .cmd = XENPF_get_cpuinfo, 281 .interface_version = XENPF_INTERFACE_VERSION, 282 .u.pcpu_info.xen_cpuid = cpu, 283 }; 284 285 ret = HYPERVISOR_platform_op(&op); 286 if (ret) 287 return ret; 288 289 info = &op.u.pcpu_info; 290 if (max_cpu) 291 *max_cpu = info->max_present; 292 293 pcpu = get_pcpu(cpu); 294 295 /* 296 * Only those at cpu present map has its sys interface. 297 */ 298 if (info->flags & XEN_PCPU_FLAGS_INVALID) { 299 unregister_and_remove_pcpu(pcpu); 300 return 0; 301 } 302 303 if (!pcpu) { 304 pcpu = create_and_register_pcpu(info); 305 if (IS_ERR_OR_NULL(pcpu)) 306 return -ENODEV; 307 } else 308 pcpu_online_status(info, pcpu); 309 310 return 0; 311 } 312 313 /* 314 * Sync dom0's pcpu information with xen hypervisor's 315 */ 316 static int xen_sync_pcpus(void) 317 { 318 /* 319 * Boot cpu always have cpu_id 0 in xen 320 */ 321 uint32_t cpu = 0, max_cpu = 0; 322 int err = 0; 323 struct pcpu *pcpu, *tmp; 324 325 mutex_lock(&xen_pcpu_lock); 326 327 while (!err && (cpu <= max_cpu)) { 328 err = sync_pcpu(cpu, &max_cpu); 329 cpu++; 330 } 331 332 if (err) 333 list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list) 334 unregister_and_remove_pcpu(pcpu); 335 336 mutex_unlock(&xen_pcpu_lock); 337 338 return err; 339 } 340 341 static void xen_pcpu_work_fn(struct work_struct *work) 342 { 343 xen_sync_pcpus(); 344 } 345 static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn); 346 347 static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id) 348 { 349 schedule_work(&xen_pcpu_work); 350 return IRQ_HANDLED; 351 } 352 353 static int __init xen_pcpu_init(void) 354 { 355 int irq, ret; 356 357 if (!xen_initial_domain()) 358 return -ENODEV; 359 360 irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0, 361 xen_pcpu_interrupt, 0, 362 "xen-pcpu", NULL); 363 if (irq < 0) { 364 pr_warn("Failed to bind pcpu virq\n"); 365 return irq; 366 } 367 368 ret = subsys_system_register(&xen_pcpu_subsys, NULL); 369 if (ret) { 370 pr_warn("Failed to register pcpu subsys\n"); 371 goto err1; 372 } 373 374 ret = xen_sync_pcpus(); 375 if (ret) { 376 pr_warn("Failed to sync pcpu info\n"); 377 goto err2; 378 } 379 380 return 0; 381 382 err2: 383 bus_unregister(&xen_pcpu_subsys); 384 err1: 385 unbind_from_irqhandler(irq, NULL); 386 return ret; 387 } 388 arch_initcall(xen_pcpu_init); 389 390 #ifdef CONFIG_ACPI 391 bool __init xen_processor_present(uint32_t acpi_id) 392 { 393 const struct pcpu *pcpu; 394 bool online = false; 395 396 mutex_lock(&xen_pcpu_lock); 397 list_for_each_entry(pcpu, &xen_pcpus, list) 398 if (pcpu->acpi_id == acpi_id) { 399 online = pcpu->flags & XEN_PCPU_FLAGS_ONLINE; 400 break; 401 } 402 mutex_unlock(&xen_pcpu_lock); 403 404 return online; 405 } 406 407 void xen_sanitize_proc_cap_bits(uint32_t *cap) 408 { 409 struct xen_platform_op op = { 410 .cmd = XENPF_set_processor_pminfo, 411 .u.set_pminfo.id = -1, 412 .u.set_pminfo.type = XEN_PM_PDC, 413 }; 414 u32 buf[3] = { ACPI_PDC_REVISION_ID, 1, *cap }; 415 int ret; 416 417 set_xen_guest_handle(op.u.set_pminfo.pdc, buf); 418 ret = HYPERVISOR_platform_op(&op); 419 if (ret) 420 pr_err("sanitize of _PDC buffer bits from Xen failed: %d\n", 421 ret); 422 else 423 *cap = buf[2]; 424 } 425 #endif 426