arch/x86/xen/enlighten.c

   1 #include <linux/cpu.h>
   2 #include <linux/kexec.h>
   3
   4 #include <xen/features.h>
   5 #include <xen/page.h>
   6
   7 #include <asm/xen/hypercall.h>
   8 #include <asm/xen/hypervisor.h>
   9 #include <asm/cpu.h>
  10 #include <asm/e820/api.h>
  11
  12 #include "xen-ops.h"
  13 #include "smp.h"
  14 #include "pmu.h"
  15
  16 EXPORT_SYMBOL_GPL(hypercall_page);
  17
  18 /*
  19  * Pointer to the xen_vcpu_info structure or
  20  * &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
  21  * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
  22  * but if the hypervisor supports VCPUOP_register_vcpu_info then it can point
  23  * to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to
  24  * acknowledge pending events.
  25  * Also more subtly it is used by the patched version of irq enable/disable
  26  * e.g. xen_irq_enable_direct and xen_iret in PV mode.
  27  *
  28  * The desire to be able to do those mask/unmask operations as a single
  29  * instruction by using the per-cpu offset held in %gs is the real reason
  30  * vcpu info is in a per-cpu pointer and the original reason for this
  31  * hypercall.
  32  *
  33  */
  34 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
  35
  36 /*
  37  * Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info
  38  * hypercall. This can be used both in PV and PVHVM mode. The structure
  39  * overrides the default per_cpu(xen_vcpu, cpu) value.
  40  */
  41 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
  42
  43 /* Linux <-> Xen vCPU id mapping */
  44 DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
  45 EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
  46
  47 enum xen_domain_type xen_domain_type = XEN_NATIVE;
  48 EXPORT_SYMBOL_GPL(xen_domain_type);
  49
  50 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
  51 EXPORT_SYMBOL(machine_to_phys_mapping);
  52 unsigned long  machine_to_phys_nr;
  53 EXPORT_SYMBOL(machine_to_phys_nr);
  54
  55 struct start_info *xen_start_info;
  56 EXPORT_SYMBOL_GPL(xen_start_info);
  57
  58 struct shared_info xen_dummy_shared_info;
  59
  60 __read_mostly int xen_have_vector_callback;
  61 EXPORT_SYMBOL_GPL(xen_have_vector_callback);
  62
  63 /*
  64  * Point at some empty memory to start with. We map the real shared_info
  65  * page as soon as fixmap is up and running.
  66  */
  67 struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info;
  68
  69 /*
  70  * Flag to determine whether vcpu info placement is available on all
  71  * VCPUs.  We assume it is to start with, and then set it to zero on
  72  * the first failure.  This is because it can succeed on some VCPUs
  73  * and not others, since it can involve hypervisor memory allocation,
  74  * or because the guest failed to guarantee all the appropriate
  75  * constraints on all VCPUs (ie buffer can't cross a page boundary).
  76  *
  77  * Note that any particular CPU may be using a placed vcpu structure,
  78  * but we can only optimise if the all are.
  79  *
  80  * 0: not available, 1: available
  81  */
  82 int xen_have_vcpu_info_placement = 1;
  83
  84 static int xen_cpu_up_online(unsigned int cpu)
  85 {
  86         xen_init_lock_cpu(cpu);
  87         return 0;
  88 }
  89
  90 int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
  91                     int (*cpu_dead_cb)(unsigned int))
  92 {
  93         int rc;
  94
  95         rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
  96                                        "x86/xen/hvm_guest:prepare",
  97                                        cpu_up_prepare_cb, cpu_dead_cb);
  98         if (rc >= 0) {
  99                 rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 100                                                "x86/xen/hvm_guest:online",
 101                                                xen_cpu_up_online, NULL);
 102                 if (rc < 0)
 103                         cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
 104         }
 105
 106         return rc >= 0 ? 0 : rc;
 107 }
 108
 109 static void clamp_max_cpus(void)
 110 {
 111 #ifdef CONFIG_SMP
 112         if (setup_max_cpus > MAX_VIRT_CPUS)
 113                 setup_max_cpus = MAX_VIRT_CPUS;
 114 #endif
 115 }
 116
 117 void xen_vcpu_setup(int cpu)
 118 {
 119         struct vcpu_register_vcpu_info info;
 120         int err;
 121         struct vcpu_info *vcpup;
 122
 123         BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
 124
 125         /*
 126          * This path is called twice on PVHVM - first during bootup via
 127          * smp_init -> xen_hvm_cpu_notify, and then if the VCPU is being
 128          * hotplugged: cpu_up -> xen_hvm_cpu_notify.
 129          * As we can only do the VCPUOP_register_vcpu_info once lets
 130          * not over-write its result.
 131          *
 132          * For PV it is called during restore (xen_vcpu_restore) and bootup
 133          * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
 134          * use this function.
 135          */
 136         if (xen_hvm_domain()) {
 137                 if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
 138                         return;
 139         }
 140         if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS)
 141                 per_cpu(xen_vcpu, cpu) =
 142                         &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
 143
 144         if (!xen_have_vcpu_info_placement) {
 145                 if (cpu >= MAX_VIRT_CPUS)
 146                         clamp_max_cpus();
 147                 return;
 148         }
 149
 150         vcpup = &per_cpu(xen_vcpu_info, cpu);
 151         info.mfn = arbitrary_virt_to_mfn(vcpup);
 152         info.offset = offset_in_page(vcpup);
 153
 154         /* Check to see if the hypervisor will put the vcpu_info
 155            structure where we want it, which allows direct access via
 156            a percpu-variable.
 157            N.B. This hypercall can _only_ be called once per CPU. Subsequent
 158            calls will error out with -EINVAL. This is due to the fact that
 159            hypervisor has no unregister variant and this hypercall does not
 160            allow to over-write info.mfn and info.offset.
 161          */
 162         err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cpu),
 163                                  &info);
 164
 165         if (err) {
 166                 printk(KERN_DEBUG "register_vcpu_info failed: err=%d\n", err);
 167                 xen_have_vcpu_info_placement = 0;
 168                 clamp_max_cpus();
 169         } else {
 170                 /* This cpu is using the registered vcpu info, even if
 171                    later ones fail to. */
 172                 per_cpu(xen_vcpu, cpu) = vcpup;
 173         }
 174 }
 175
 176 void xen_reboot(int reason)
 177 {
 178         struct sched_shutdown r = { .reason = reason };
 179         int cpu;
 180
 181         for_each_online_cpu(cpu)
 182                 xen_pmu_finish(cpu);
 183
 184         if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
 185                 BUG();
 186 }
 187
 188 void xen_emergency_restart(void)
 189 {
 190         xen_reboot(SHUTDOWN_reboot);
 191 }
 192
 193 static int
 194 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
 195 {
 196         if (!kexec_crash_loaded())
 197                 xen_reboot(SHUTDOWN_crash);
 198         return NOTIFY_DONE;
 199 }
 200
 201 static struct notifier_block xen_panic_block = {
 202         .notifier_call = xen_panic_event,
 203         .priority = INT_MIN
 204 };
 205
 206 int xen_panic_handler_init(void)
 207 {
 208         atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
 209         return 0;
 210 }
 211
 212 void xen_pin_vcpu(int cpu)
 213 {
 214         static bool disable_pinning;
 215         struct sched_pin_override pin_override;
 216         int ret;
 217
 218         if (disable_pinning)
 219                 return;
 220
 221         pin_override.pcpu = cpu;
 222         ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
 223
 224         /* Ignore errors when removing override. */
 225         if (cpu < 0)
 226                 return;
 227
 228         switch (ret) {
 229         case -ENOSYS:
 230                 pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
 231                         cpu);
 232                 disable_pinning = true;
 233                 break;
 234         case -EPERM:
 235                 WARN(1, "Trying to pin vcpu without having privilege to do so\n");
 236                 disable_pinning = true;
 237                 break;
 238         case -EINVAL:
 239         case -EBUSY:
 240                 pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
 241                         cpu);
 242                 break;
 243         case 0:
 244                 break;
 245         default:
 246                 WARN(1, "rc %d while trying to pin vcpu\n", ret);
 247                 disable_pinning = true;
 248         }
 249 }
 250
 251 #ifdef CONFIG_HOTPLUG_CPU
 252 void xen_arch_register_cpu(int num)
 253 {
 254         arch_register_cpu(num);
 255 }
 256 EXPORT_SYMBOL(xen_arch_register_cpu);
 257
 258 void xen_arch_unregister_cpu(int num)
 259 {
 260         arch_unregister_cpu(num);
 261 }
 262 EXPORT_SYMBOL(xen_arch_unregister_cpu);
 263 #endif