arch/x86/xen/enlighten.c

   1 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
   2 #include <linux/bootmem.h>
   3 #endif
   4 #include <linux/cpu.h>
   5 #include <linux/kexec.h>
   6 #include <linux/slab.h>
   7
   8 #include <xen/features.h>
   9 #include <xen/page.h>
  10
  11 #include <asm/xen/hypercall.h>
  12 #include <asm/xen/hypervisor.h>
  13 #include <asm/cpu.h>
  14 #include <asm/e820/api.h>
  15
  16 #include "xen-ops.h"
  17 #include "smp.h"
  18 #include "pmu.h"
  19
  20 EXPORT_SYMBOL_GPL(hypercall_page);
  21
  22 /*
  23  * Pointer to the xen_vcpu_info structure or
  24  * &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
  25  * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
  26  * but if the hypervisor supports VCPUOP_register_vcpu_info then it can point
  27  * to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to
  28  * acknowledge pending events.
  29  * Also more subtly it is used by the patched version of irq enable/disable
  30  * e.g. xen_irq_enable_direct and xen_iret in PV mode.
  31  *
  32  * The desire to be able to do those mask/unmask operations as a single
  33  * instruction by using the per-cpu offset held in %gs is the real reason
  34  * vcpu info is in a per-cpu pointer and the original reason for this
  35  * hypercall.
  36  *
  37  */
  38 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
  39
  40 /*
  41  * Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info
  42  * hypercall. This can be used both in PV and PVHVM mode. The structure
  43  * overrides the default per_cpu(xen_vcpu, cpu) value.
  44  */
  45 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
  46
  47 /* Linux <-> Xen vCPU id mapping */
  48 DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
  49 EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
  50
  51 enum xen_domain_type xen_domain_type = XEN_NATIVE;
  52 EXPORT_SYMBOL_GPL(xen_domain_type);
  53
  54 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
  55 EXPORT_SYMBOL(machine_to_phys_mapping);
  56 unsigned long  machine_to_phys_nr;
  57 EXPORT_SYMBOL(machine_to_phys_nr);
  58
  59 struct start_info *xen_start_info;
  60 EXPORT_SYMBOL_GPL(xen_start_info);
  61
  62 struct shared_info xen_dummy_shared_info;
  63
  64 __read_mostly int xen_have_vector_callback;
  65 EXPORT_SYMBOL_GPL(xen_have_vector_callback);
  66
  67 /*
  68  * Point at some empty memory to start with. We map the real shared_info
  69  * page as soon as fixmap is up and running.
  70  */
  71 struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info;
  72
  73 /*
  74  * Flag to determine whether vcpu info placement is available on all
  75  * VCPUs.  We assume it is to start with, and then set it to zero on
  76  * the first failure.  This is because it can succeed on some VCPUs
  77  * and not others, since it can involve hypervisor memory allocation,
  78  * or because the guest failed to guarantee all the appropriate
  79  * constraints on all VCPUs (ie buffer can't cross a page boundary).
  80  *
  81  * Note that any particular CPU may be using a placed vcpu structure,
  82  * but we can only optimise if the all are.
  83  *
  84  * 0: not available, 1: available
  85  */
  86 int xen_have_vcpu_info_placement = 1;
  87
  88 static int xen_cpu_up_online(unsigned int cpu)
  89 {
  90         xen_init_lock_cpu(cpu);
  91         return 0;
  92 }
  93
  94 int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
  95                     int (*cpu_dead_cb)(unsigned int))
  96 {
  97         int rc;
  98
  99         rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
 100                                        "x86/xen/guest:prepare",
 101                                        cpu_up_prepare_cb, cpu_dead_cb);
 102         if (rc >= 0) {
 103                 rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 104                                                "x86/xen/guest:online",
 105                                                xen_cpu_up_online, NULL);
 106                 if (rc < 0)
 107                         cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
 108         }
 109
 110         return rc >= 0 ? 0 : rc;
 111 }
 112
 113 static int xen_vcpu_setup_restore(int cpu)
 114 {
 115         int rc = 0;
 116
 117         /* Any per_cpu(xen_vcpu) is stale, so reset it */
 118         xen_vcpu_info_reset(cpu);
 119
 120         /*
 121          * For PVH and PVHVM, setup online VCPUs only. The rest will
 122          * be handled by hotplug.
 123          */
 124         if (xen_pv_domain() ||
 125             (xen_hvm_domain() && cpu_online(cpu))) {
 126                 rc = xen_vcpu_setup(cpu);
 127         }
 128
 129         return rc;
 130 }
 131
 132 /*
 133  * On restore, set the vcpu placement up again.
 134  * If it fails, then we're in a bad state, since
 135  * we can't back out from using it...
 136  */
 137 void xen_vcpu_restore(void)
 138 {
 139         int cpu, rc;
 140
 141         for_each_possible_cpu(cpu) {
 142                 bool other_cpu = (cpu != smp_processor_id());
 143                 bool is_up;
 144
 145                 if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
 146                         continue;
 147
 148                 /* Only Xen 4.5 and higher support this. */
 149                 is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
 150                                            xen_vcpu_nr(cpu), NULL) > 0;
 151
 152                 if (other_cpu && is_up &&
 153                     HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
 154                         BUG();
 155
 156                 if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
 157                         xen_setup_runstate_info(cpu);
 158
 159                 rc = xen_vcpu_setup_restore(cpu);
 160                 if (rc)
 161                         pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
 162                                         "System will hang.\n", cpu, rc);
 163                 /*
 164                  * In case xen_vcpu_setup_restore() fails, do not bring up the
 165                  * VCPU. This helps us avoid the resulting OOPS when the VCPU
 166                  * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
 167                  * Note that this does not improve the situation much -- now the
 168                  * VM hangs instead of OOPSing -- with the VCPUs that did not
 169                  * fail, spinning in stop_machine(), waiting for the failed
 170                  * VCPUs to come up.
 171                  */
 172                 if (other_cpu && is_up && (rc == 0) &&
 173                     HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
 174                         BUG();
 175         }
 176 }
 177
 178 void xen_vcpu_info_reset(int cpu)
 179 {
 180         if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
 181                 per_cpu(xen_vcpu, cpu) =
 182                         &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
 183         } else {
 184                 /* Set to NULL so that if somebody accesses it we get an OOPS */
 185                 per_cpu(xen_vcpu, cpu) = NULL;
 186         }
 187 }
 188
 189 int xen_vcpu_setup(int cpu)
 190 {
 191         struct vcpu_register_vcpu_info info;
 192         int err;
 193         struct vcpu_info *vcpup;
 194
 195         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
 196
 197         /*
 198          * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
 199          * and at restore (xen_vcpu_restore). Also called for hotplugged
 200          * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
 201          * However, the hypercall can only be done once (see below) so if a VCPU
 202          * is offlined and comes back online then let's not redo the hypercall.
 203          *
 204          * For PV it is called during restore (xen_vcpu_restore) and bootup
 205          * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
 206          * use this function.
 207          */
 208         if (xen_hvm_domain()) {
 209                 if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
 210                         return 0;
 211         }
 212
 213         if (xen_have_vcpu_info_placement) {
 214                 vcpup = &per_cpu(xen_vcpu_info, cpu);
 215                 info.mfn = arbitrary_virt_to_mfn(vcpup);
 216                 info.offset = offset_in_page(vcpup);
 217
 218                 /*
 219                  * Check to see if the hypervisor will put the vcpu_info
 220                  * structure where we want it, which allows direct access via
 221                  * a percpu-variable.
 222                  * N.B. This hypercall can _only_ be called once per CPU.
 223                  * Subsequent calls will error out with -EINVAL. This is due to
 224                  * the fact that hypervisor has no unregister variant and this
 225                  * hypercall does not allow to over-write info.mfn and
 226                  * info.offset.
 227                  */
 228                 err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
 229                                          xen_vcpu_nr(cpu), &info);
 230
 231                 if (err) {
 232                         pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
 233                                      cpu, err);
 234                         xen_have_vcpu_info_placement = 0;
 235                 } else {
 236                         /*
 237                          * This cpu is using the registered vcpu info, even if
 238                          * later ones fail to.
 239                          */
 240                         per_cpu(xen_vcpu, cpu) = vcpup;
 241                 }
 242         }
 243
 244         if (!xen_have_vcpu_info_placement)
 245                 xen_vcpu_info_reset(cpu);
 246
 247         return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
 248 }
 249
 250 void xen_reboot(int reason)
 251 {
 252         struct sched_shutdown r = { .reason = reason };
 253         int cpu;
 254
 255         for_each_online_cpu(cpu)
 256                 xen_pmu_finish(cpu);
 257
 258         if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
 259                 BUG();
 260 }
 261
 262 static int reboot_reason = SHUTDOWN_reboot;
 263 static bool xen_legacy_crash;
 264 void xen_emergency_restart(void)
 265 {
 266         xen_reboot(reboot_reason);
 267 }
 268
 269 static int
 270 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
 271 {
 272         if (!kexec_crash_loaded()) {
 273                 if (xen_legacy_crash)
 274                         xen_reboot(SHUTDOWN_crash);
 275
 276                 reboot_reason = SHUTDOWN_crash;
 277
 278                 /*
 279                  * If panic_timeout==0 then we are supposed to wait forever.
 280                  * However, to preserve original dom0 behavior we have to drop
 281                  * into hypervisor. (domU behavior is controlled by its
 282                  * config file)
 283                  */
 284                 if (panic_timeout == 0)
 285                         panic_timeout = -1;
 286         }
 287         return NOTIFY_DONE;
 288 }
 289
 290 static int __init parse_xen_legacy_crash(char *arg)
 291 {
 292         xen_legacy_crash = true;
 293         return 0;
 294 }
 295 early_param("xen_legacy_crash", parse_xen_legacy_crash);
 296
 297 static struct notifier_block xen_panic_block = {
 298         .notifier_call = xen_panic_event,
 299         .priority = INT_MIN
 300 };
 301
 302 int xen_panic_handler_init(void)
 303 {
 304         atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
 305         return 0;
 306 }
 307
 308 void xen_pin_vcpu(int cpu)
 309 {
 310         static bool disable_pinning;
 311         struct sched_pin_override pin_override;
 312         int ret;
 313
 314         if (disable_pinning)
 315                 return;
 316
 317         pin_override.pcpu = cpu;
 318         ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
 319
 320         /* Ignore errors when removing override. */
 321         if (cpu < 0)
 322                 return;
 323
 324         switch (ret) {
 325         case -ENOSYS:
 326                 pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
 327                         cpu);
 328                 disable_pinning = true;
 329                 break;
 330         case -EPERM:
 331                 WARN(1, "Trying to pin vcpu without having privilege to do so\n");
 332                 disable_pinning = true;
 333                 break;
 334         case -EINVAL:
 335         case -EBUSY:
 336                 pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
 337                         cpu);
 338                 break;
 339         case 0:
 340                 break;
 341         default:
 342                 WARN(1, "rc %d while trying to pin vcpu\n", ret);
 343                 disable_pinning = true;
 344         }
 345 }
 346
 347 #ifdef CONFIG_HOTPLUG_CPU
 348 void xen_arch_register_cpu(int num)
 349 {
 350         arch_register_cpu(num);
 351 }
 352 EXPORT_SYMBOL(xen_arch_register_cpu);
 353
 354 void xen_arch_unregister_cpu(int num)
 355 {
 356         arch_unregister_cpu(num);
 357 }
 358 EXPORT_SYMBOL(xen_arch_unregister_cpu);
 359 #endif