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