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 51 /* 52 * @cpu_id: Xen physical cpu logic number 53 * @flags: Xen physical cpu status flag 54 * - XEN_PCPU_FLAGS_ONLINE: cpu is online 55 * - XEN_PCPU_FLAGS_INVALID: cpu is not present 56 */ 57 struct pcpu { 58 struct list_head list; 59 struct device dev; 60 uint32_t cpu_id; 61 uint32_t acpi_id; 62 uint32_t flags; 63 }; 64 65 static struct bus_type xen_pcpu_subsys = { 66 .name = "xen_cpu", 67 .dev_name = "xen_cpu", 68 }; 69 70 static DEFINE_MUTEX(xen_pcpu_lock); 71 72 static LIST_HEAD(xen_pcpus); 73 74 static int xen_pcpu_down(uint32_t cpu_id) 75 { 76 struct xen_platform_op op = { 77 .cmd = XENPF_cpu_offline, 78 .interface_version = XENPF_INTERFACE_VERSION, 79 .u.cpu_ol.cpuid = cpu_id, 80 }; 81 82 return HYPERVISOR_platform_op(&op); 83 } 84 85 static int xen_pcpu_up(uint32_t cpu_id) 86 { 87 struct xen_platform_op op = { 88 .cmd = XENPF_cpu_online, 89 .interface_version = XENPF_INTERFACE_VERSION, 90 .u.cpu_ol.cpuid = cpu_id, 91 }; 92 93 return HYPERVISOR_platform_op(&op); 94 } 95 96 static ssize_t online_show(struct device *dev, 97 struct device_attribute *attr, 98 char *buf) 99 { 100 struct pcpu *cpu = container_of(dev, struct pcpu, dev); 101 102 return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE)); 103 } 104 105 static ssize_t __ref online_store(struct device *dev, 106 struct device_attribute *attr, 107 const char *buf, size_t count) 108 { 109 struct pcpu *pcpu = container_of(dev, struct pcpu, dev); 110 unsigned long long val; 111 ssize_t ret; 112 113 if (!capable(CAP_SYS_ADMIN)) 114 return -EPERM; 115 116 if (kstrtoull(buf, 0, &val) < 0) 117 return -EINVAL; 118 119 switch (val) { 120 case 0: 121 ret = xen_pcpu_down(pcpu->cpu_id); 122 break; 123 case 1: 124 ret = xen_pcpu_up(pcpu->cpu_id); 125 break; 126 default: 127 ret = -EINVAL; 128 } 129 130 if (ret >= 0) 131 ret = count; 132 return ret; 133 } 134 static DEVICE_ATTR_RW(online); 135 136 static struct attribute *pcpu_dev_attrs[] = { 137 &dev_attr_online.attr, 138 NULL 139 }; 140 141 static umode_t pcpu_dev_is_visible(struct kobject *kobj, 142 struct attribute *attr, int idx) 143 { 144 struct device *dev = kobj_to_dev(kobj); 145 /* 146 * Xen never offline cpu0 due to several restrictions 147 * and assumptions. This basically doesn't add a sys control 148 * to user, one cannot attempt to offline BSP. 149 */ 150 return dev->id ? attr->mode : 0; 151 } 152 153 static const struct attribute_group pcpu_dev_group = { 154 .attrs = pcpu_dev_attrs, 155 .is_visible = pcpu_dev_is_visible, 156 }; 157 158 static const struct attribute_group *pcpu_dev_groups[] = { 159 &pcpu_dev_group, 160 NULL 161 }; 162 163 static bool xen_pcpu_online(uint32_t flags) 164 { 165 return !!(flags & XEN_PCPU_FLAGS_ONLINE); 166 } 167 168 static void pcpu_online_status(struct xenpf_pcpuinfo *info, 169 struct pcpu *pcpu) 170 { 171 if (xen_pcpu_online(info->flags) && 172 !xen_pcpu_online(pcpu->flags)) { 173 /* the pcpu is onlined */ 174 pcpu->flags |= XEN_PCPU_FLAGS_ONLINE; 175 kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE); 176 } else if (!xen_pcpu_online(info->flags) && 177 xen_pcpu_online(pcpu->flags)) { 178 /* The pcpu is offlined */ 179 pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE; 180 kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE); 181 } 182 } 183 184 static struct pcpu *get_pcpu(uint32_t cpu_id) 185 { 186 struct pcpu *pcpu; 187 188 list_for_each_entry(pcpu, &xen_pcpus, list) { 189 if (pcpu->cpu_id == cpu_id) 190 return pcpu; 191 } 192 193 return NULL; 194 } 195 196 static void pcpu_release(struct device *dev) 197 { 198 struct pcpu *pcpu = container_of(dev, struct pcpu, dev); 199 200 list_del(&pcpu->list); 201 kfree(pcpu); 202 } 203 204 static void unregister_and_remove_pcpu(struct pcpu *pcpu) 205 { 206 struct device *dev; 207 208 if (!pcpu) 209 return; 210 211 dev = &pcpu->dev; 212 /* pcpu remove would be implicitly done */ 213 device_unregister(dev); 214 } 215 216 static int register_pcpu(struct pcpu *pcpu) 217 { 218 struct device *dev; 219 int err = -EINVAL; 220 221 if (!pcpu) 222 return err; 223 224 dev = &pcpu->dev; 225 dev->bus = &xen_pcpu_subsys; 226 dev->id = pcpu->cpu_id; 227 dev->release = pcpu_release; 228 dev->groups = pcpu_dev_groups; 229 230 err = device_register(dev); 231 if (err) { 232 put_device(dev); 233 return err; 234 } 235 236 return 0; 237 } 238 239 static struct pcpu *create_and_register_pcpu(struct xenpf_pcpuinfo *info) 240 { 241 struct pcpu *pcpu; 242 int err; 243 244 if (info->flags & XEN_PCPU_FLAGS_INVALID) 245 return ERR_PTR(-ENODEV); 246 247 pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL); 248 if (!pcpu) 249 return ERR_PTR(-ENOMEM); 250 251 INIT_LIST_HEAD(&pcpu->list); 252 pcpu->cpu_id = info->xen_cpuid; 253 pcpu->acpi_id = info->acpi_id; 254 pcpu->flags = info->flags; 255 256 /* Need hold on xen_pcpu_lock before pcpu list manipulations */ 257 list_add_tail(&pcpu->list, &xen_pcpus); 258 259 err = register_pcpu(pcpu); 260 if (err) { 261 pr_warn("Failed to register pcpu%u\n", info->xen_cpuid); 262 return ERR_PTR(-ENOENT); 263 } 264 265 return pcpu; 266 } 267 268 /* 269 * Caller should hold the xen_pcpu_lock 270 */ 271 static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu) 272 { 273 int ret; 274 struct pcpu *pcpu = NULL; 275 struct xenpf_pcpuinfo *info; 276 struct xen_platform_op op = { 277 .cmd = XENPF_get_cpuinfo, 278 .interface_version = XENPF_INTERFACE_VERSION, 279 .u.pcpu_info.xen_cpuid = cpu, 280 }; 281 282 ret = HYPERVISOR_platform_op(&op); 283 if (ret) 284 return ret; 285 286 info = &op.u.pcpu_info; 287 if (max_cpu) 288 *max_cpu = info->max_present; 289 290 pcpu = get_pcpu(cpu); 291 292 /* 293 * Only those at cpu present map has its sys interface. 294 */ 295 if (info->flags & XEN_PCPU_FLAGS_INVALID) { 296 unregister_and_remove_pcpu(pcpu); 297 return 0; 298 } 299 300 if (!pcpu) { 301 pcpu = create_and_register_pcpu(info); 302 if (IS_ERR_OR_NULL(pcpu)) 303 return -ENODEV; 304 } else 305 pcpu_online_status(info, pcpu); 306 307 return 0; 308 } 309 310 /* 311 * Sync dom0's pcpu information with xen hypervisor's 312 */ 313 static int xen_sync_pcpus(void) 314 { 315 /* 316 * Boot cpu always have cpu_id 0 in xen 317 */ 318 uint32_t cpu = 0, max_cpu = 0; 319 int err = 0; 320 struct pcpu *pcpu, *tmp; 321 322 mutex_lock(&xen_pcpu_lock); 323 324 while (!err && (cpu <= max_cpu)) { 325 err = sync_pcpu(cpu, &max_cpu); 326 cpu++; 327 } 328 329 if (err) 330 list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list) 331 unregister_and_remove_pcpu(pcpu); 332 333 mutex_unlock(&xen_pcpu_lock); 334 335 return err; 336 } 337 338 static void xen_pcpu_work_fn(struct work_struct *work) 339 { 340 xen_sync_pcpus(); 341 } 342 static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn); 343 344 static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id) 345 { 346 schedule_work(&xen_pcpu_work); 347 return IRQ_HANDLED; 348 } 349 350 static int __init xen_pcpu_init(void) 351 { 352 int irq, ret; 353 354 if (!xen_initial_domain()) 355 return -ENODEV; 356 357 irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0, 358 xen_pcpu_interrupt, 0, 359 "xen-pcpu", NULL); 360 if (irq < 0) { 361 pr_warn("Failed to bind pcpu virq\n"); 362 return irq; 363 } 364 365 ret = subsys_system_register(&xen_pcpu_subsys, NULL); 366 if (ret) { 367 pr_warn("Failed to register pcpu subsys\n"); 368 goto err1; 369 } 370 371 ret = xen_sync_pcpus(); 372 if (ret) { 373 pr_warn("Failed to sync pcpu info\n"); 374 goto err2; 375 } 376 377 return 0; 378 379 err2: 380 bus_unregister(&xen_pcpu_subsys); 381 err1: 382 unbind_from_irqhandler(irq, NULL); 383 return ret; 384 } 385 arch_initcall(xen_pcpu_init); 386 387 #ifdef CONFIG_ACPI 388 bool __init xen_processor_present(uint32_t acpi_id) 389 { 390 const struct pcpu *pcpu; 391 bool online = false; 392 393 mutex_lock(&xen_pcpu_lock); 394 list_for_each_entry(pcpu, &xen_pcpus, list) 395 if (pcpu->acpi_id == acpi_id) { 396 online = pcpu->flags & XEN_PCPU_FLAGS_ONLINE; 397 break; 398 } 399 mutex_unlock(&xen_pcpu_lock); 400 401 return online; 402 } 403 #endif 404