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
   7 #include <xen/features.h>
   8 #include <xen/page.h>
   9 #include <xen/interface/memory.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  * NB: needs to live in .data because it's used by xen_prepare_pvh which runs
  69  * before clearing the bss.
  70  */
  71 uint32_t xen_start_flags __attribute__((section(".data"))) = 0;
  72 EXPORT_SYMBOL(xen_start_flags);
  73
  74 /*
  75  * Point at some empty memory to start with. We map the real shared_info
  76  * page as soon as fixmap is up and running.
  77  */
  78 struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info;
  79
  80 /*
  81  * Flag to determine whether vcpu info placement is available on all
  82  * VCPUs.  We assume it is to start with, and then set it to zero on
  83  * the first failure.  This is because it can succeed on some VCPUs
  84  * and not others, since it can involve hypervisor memory allocation,
  85  * or because the guest failed to guarantee all the appropriate
  86  * constraints on all VCPUs (ie buffer can't cross a page boundary).
  87  *
  88  * Note that any particular CPU may be using a placed vcpu structure,
  89  * but we can only optimise if the all are.
  90  *
  91  * 0: not available, 1: available
  92  */
  93 int xen_have_vcpu_info_placement = 1;
  94
  95 static int xen_cpu_up_online(unsigned int cpu)
  96 {
  97         xen_init_lock_cpu(cpu);
  98         return 0;
  99 }
 100
 101 int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
 102                     int (*cpu_dead_cb)(unsigned int))
 103 {
 104         int rc;
 105
 106         rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
 107                                        "x86/xen/guest:prepare",
 108                                        cpu_up_prepare_cb, cpu_dead_cb);
 109         if (rc >= 0) {
 110                 rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 111                                                "x86/xen/guest:online",
 112                                                xen_cpu_up_online, NULL);
 113                 if (rc < 0)
 114                         cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
 115         }
 116
 117         return rc >= 0 ? 0 : rc;
 118 }
 119
 120 static int xen_vcpu_setup_restore(int cpu)
 121 {
 122         int rc = 0;
 123
 124         /* Any per_cpu(xen_vcpu) is stale, so reset it */
 125         xen_vcpu_info_reset(cpu);
 126
 127         /*
 128          * For PVH and PVHVM, setup online VCPUs only. The rest will
 129          * be handled by hotplug.
 130          */
 131         if (xen_pv_domain() ||
 132             (xen_hvm_domain() && cpu_online(cpu))) {
 133                 rc = xen_vcpu_setup(cpu);
 134         }
 135
 136         return rc;
 137 }
 138
 139 /*
 140  * On restore, set the vcpu placement up again.
 141  * If it fails, then we're in a bad state, since
 142  * we can't back out from using it...
 143  */
 144 void xen_vcpu_restore(void)
 145 {
 146         int cpu, rc;
 147
 148         for_each_possible_cpu(cpu) {
 149                 bool other_cpu = (cpu != smp_processor_id());
 150                 bool is_up;
 151
 152                 if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
 153                         continue;
 154
 155                 /* Only Xen 4.5 and higher support this. */
 156                 is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
 157                                            xen_vcpu_nr(cpu), NULL) > 0;
 158
 159                 if (other_cpu && is_up &&
 160                     HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
 161                         BUG();
 162
 163                 if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
 164                         xen_setup_runstate_info(cpu);
 165
 166                 rc = xen_vcpu_setup_restore(cpu);
 167                 if (rc)
 168                         pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
 169                                         "System will hang.\n", cpu, rc);
 170                 /*
 171                  * In case xen_vcpu_setup_restore() fails, do not bring up the
 172                  * VCPU. This helps us avoid the resulting OOPS when the VCPU
 173                  * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
 174                  * Note that this does not improve the situation much -- now the
 175                  * VM hangs instead of OOPSing -- with the VCPUs that did not
 176                  * fail, spinning in stop_machine(), waiting for the failed
 177                  * VCPUs to come up.
 178                  */
 179                 if (other_cpu && is_up && (rc == 0) &&
 180                     HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
 181                         BUG();
 182         }
 183 }
 184
 185 void xen_vcpu_info_reset(int cpu)
 186 {
 187         if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
 188                 per_cpu(xen_vcpu, cpu) =
 189                         &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
 190         } else {
 191                 /* Set to NULL so that if somebody accesses it we get an OOPS */
 192                 per_cpu(xen_vcpu, cpu) = NULL;
 193         }
 194 }
 195
 196 int xen_vcpu_setup(int cpu)
 197 {
 198         struct vcpu_register_vcpu_info info;
 199         int err;
 200         struct vcpu_info *vcpup;
 201
 202         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
 203
 204         /*
 205          * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
 206          * and at restore (xen_vcpu_restore). Also called for hotplugged
 207          * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
 208          * However, the hypercall can only be done once (see below) so if a VCPU
 209          * is offlined and comes back online then let's not redo the hypercall.
 210          *
 211          * For PV it is called during restore (xen_vcpu_restore) and bootup
 212          * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
 213          * use this function.
 214          */
 215         if (xen_hvm_domain()) {
 216                 if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
 217                         return 0;
 218         }
 219
 220         if (xen_have_vcpu_info_placement) {
 221                 vcpup = &per_cpu(xen_vcpu_info, cpu);
 222                 info.mfn = arbitrary_virt_to_mfn(vcpup);
 223                 info.offset = offset_in_page(vcpup);
 224
 225                 /*
 226                  * Check to see if the hypervisor will put the vcpu_info
 227                  * structure where we want it, which allows direct access via
 228                  * a percpu-variable.
 229                  * N.B. This hypercall can _only_ be called once per CPU.
 230                  * Subsequent calls will error out with -EINVAL. This is due to
 231                  * the fact that hypervisor has no unregister variant and this
 232                  * hypercall does not allow to over-write info.mfn and
 233                  * info.offset.
 234                  */
 235                 err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
 236                                          xen_vcpu_nr(cpu), &info);
 237
 238                 if (err) {
 239                         pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
 240                                      cpu, err);
 241                         xen_have_vcpu_info_placement = 0;
 242                 } else {
 243                         /*
 244                          * This cpu is using the registered vcpu info, even if
 245                          * later ones fail to.
 246                          */
 247                         per_cpu(xen_vcpu, cpu) = vcpup;
 248                 }
 249         }
 250
 251         if (!xen_have_vcpu_info_placement)
 252                 xen_vcpu_info_reset(cpu);
 253
 254         return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
 255 }
 256
 257 void xen_reboot(int reason)
 258 {
 259         struct sched_shutdown r = { .reason = reason };
 260         int cpu;
 261
 262         for_each_online_cpu(cpu)
 263                 xen_pmu_finish(cpu);
 264
 265         if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
 266                 BUG();
 267 }
 268
 269 void xen_emergency_restart(void)
 270 {
 271         xen_reboot(SHUTDOWN_reboot);
 272 }
 273
 274 static int
 275 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
 276 {
 277         if (!kexec_crash_loaded())
 278                 xen_reboot(SHUTDOWN_crash);
 279         return NOTIFY_DONE;
 280 }
 281
 282 static struct notifier_block xen_panic_block = {
 283         .notifier_call = xen_panic_event,
 284         .priority = INT_MIN
 285 };
 286
 287 int xen_panic_handler_init(void)
 288 {
 289         atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
 290         return 0;
 291 }
 292
 293 void xen_pin_vcpu(int cpu)
 294 {
 295         static bool disable_pinning;
 296         struct sched_pin_override pin_override;
 297         int ret;
 298
 299         if (disable_pinning)
 300                 return;
 301
 302         pin_override.pcpu = cpu;
 303         ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
 304
 305         /* Ignore errors when removing override. */
 306         if (cpu < 0)
 307                 return;
 308
 309         switch (ret) {
 310         case -ENOSYS:
 311                 pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
 312                         cpu);
 313                 disable_pinning = true;
 314                 break;
 315         case -EPERM:
 316                 WARN(1, "Trying to pin vcpu without having privilege to do so\n");
 317                 disable_pinning = true;
 318                 break;
 319         case -EINVAL:
 320         case -EBUSY:
 321                 pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
 322                         cpu);
 323                 break;
 324         case 0:
 325                 break;
 326         default:
 327                 WARN(1, "rc %d while trying to pin vcpu\n", ret);
 328                 disable_pinning = true;
 329         }
 330 }
 331
 332 #ifdef CONFIG_HOTPLUG_CPU
 333 void xen_arch_register_cpu(int num)
 334 {
 335         arch_register_cpu(num);
 336 }
 337 EXPORT_SYMBOL(xen_arch_register_cpu);
 338
 339 void xen_arch_unregister_cpu(int num)
 340 {
 341         arch_unregister_cpu(num);
 342 }
 343 EXPORT_SYMBOL(xen_arch_unregister_cpu);
 344 #endif
 345
 346 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
 347 void __init arch_xen_balloon_init(struct resource *hostmem_resource)
 348 {
 349         struct xen_memory_map memmap;
 350         int rc;
 351         unsigned int i, last_guest_ram;
 352         phys_addr_t max_addr = PFN_PHYS(max_pfn);
 353         struct e820_table *xen_e820_table;
 354         const struct e820_entry *entry;
 355         struct resource *res;
 356
 357         if (!xen_initial_domain())
 358                 return;
 359
 360         xen_e820_table = kmalloc(sizeof(*xen_e820_table), GFP_KERNEL);
 361         if (!xen_e820_table)
 362                 return;
 363
 364         memmap.nr_entries = ARRAY_SIZE(xen_e820_table->entries);
 365         set_xen_guest_handle(memmap.buffer, xen_e820_table->entries);
 366         rc = HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap);
 367         if (rc) {
 368                 pr_warn("%s: Can't read host e820 (%d)\n", __func__, rc);
 369                 goto out;
 370         }
 371
 372         last_guest_ram = 0;
 373         for (i = 0; i < memmap.nr_entries; i++) {
 374                 if (xen_e820_table->entries[i].addr >= max_addr)
 375                         break;
 376                 if (xen_e820_table->entries[i].type == E820_TYPE_RAM)
 377                         last_guest_ram = i;
 378         }
 379
 380         entry = &xen_e820_table->entries[last_guest_ram];
 381         if (max_addr >= entry->addr + entry->size)
 382                 goto out; /* No unallocated host RAM. */
 383
 384         hostmem_resource->start = max_addr;
 385         hostmem_resource->end = entry->addr + entry->size;
 386
 387         /*
 388          * Mark non-RAM regions between the end of dom0 RAM and end of host RAM
 389          * as unavailable. The rest of that region can be used for hotplug-based
 390          * ballooning.
 391          */
 392         for (; i < memmap.nr_entries; i++) {
 393                 entry = &xen_e820_table->entries[i];
 394
 395                 if (entry->type == E820_TYPE_RAM)
 396                         continue;
 397
 398                 if (entry->addr >= hostmem_resource->end)
 399                         break;
 400
 401                 res = kzalloc(sizeof(*res), GFP_KERNEL);
 402                 if (!res)
 403                         goto out;
 404
 405                 res->name = "Unavailable host RAM";
 406                 res->start = entry->addr;
 407                 res->end = (entry->addr + entry->size < hostmem_resource->end) ?
 408                             entry->addr + entry->size : hostmem_resource->end;
 409                 rc = insert_resource(hostmem_resource, res);
 410                 if (rc) {
 411                         pr_warn("%s: Can't insert [%llx - %llx) (%d)\n",
 412                                 __func__, res->start, res->end, rc);
 413                         kfree(res);
 414                         goto  out;
 415                 }
 416         }
 417
 418  out:
 419         kfree(xen_e820_table);
 420 }
 421 #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */