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 int xen_vcpu_setup_restore(int cpu) 110 { 111 int rc = 0; 112 113 /* Any per_cpu(xen_vcpu) is stale, so reset it */ 114 xen_vcpu_info_reset(cpu); 115 116 /* 117 * For PVH and PVHVM, setup online VCPUs only. The rest will 118 * be handled by hotplug. 119 */ 120 if (xen_pv_domain() || 121 (xen_hvm_domain() && cpu_online(cpu))) { 122 rc = xen_vcpu_setup(cpu); 123 } 124 125 return rc; 126 } 127 128 /* 129 * On restore, set the vcpu placement up again. 130 * If it fails, then we're in a bad state, since 131 * we can't back out from using it... 132 */ 133 void xen_vcpu_restore(void) 134 { 135 int cpu, rc; 136 137 for_each_possible_cpu(cpu) { 138 bool other_cpu = (cpu != smp_processor_id()); 139 bool is_up; 140 141 if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID) 142 continue; 143 144 /* Only Xen 4.5 and higher support this. */ 145 is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up, 146 xen_vcpu_nr(cpu), NULL) > 0; 147 148 if (other_cpu && is_up && 149 HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL)) 150 BUG(); 151 152 if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock)) 153 xen_setup_runstate_info(cpu); 154 155 rc = xen_vcpu_setup_restore(cpu); 156 if (rc) 157 pr_emerg_once("vcpu restore failed for cpu=%d err=%d. " 158 "System will hang.\n", cpu, rc); 159 /* 160 * In case xen_vcpu_setup_restore() fails, do not bring up the 161 * VCPU. This helps us avoid the resulting OOPS when the VCPU 162 * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.) 163 * Note that this does not improve the situation much -- now the 164 * VM hangs instead of OOPSing -- with the VCPUs that did not 165 * fail, spinning in stop_machine(), waiting for the failed 166 * VCPUs to come up. 167 */ 168 if (other_cpu && is_up && (rc == 0) && 169 HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL)) 170 BUG(); 171 } 172 } 173 174 void xen_vcpu_info_reset(int cpu) 175 { 176 if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) { 177 per_cpu(xen_vcpu, cpu) = 178 &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)]; 179 } else { 180 /* Set to NULL so that if somebody accesses it we get an OOPS */ 181 per_cpu(xen_vcpu, cpu) = NULL; 182 } 183 } 184 185 int xen_vcpu_setup(int cpu) 186 { 187 struct vcpu_register_vcpu_info info; 188 int err; 189 struct vcpu_info *vcpup; 190 191 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 192 193 /* 194 * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu) 195 * and at restore (xen_vcpu_restore). Also called for hotplugged 196 * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm). 197 * However, the hypercall can only be done once (see below) so if a VCPU 198 * is offlined and comes back online then let's not redo the hypercall. 199 * 200 * For PV it is called during restore (xen_vcpu_restore) and bootup 201 * (xen_setup_vcpu_info_placement). The hotplug mechanism does not 202 * use this function. 203 */ 204 if (xen_hvm_domain()) { 205 if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu)) 206 return 0; 207 } 208 209 if (xen_have_vcpu_info_placement) { 210 vcpup = &per_cpu(xen_vcpu_info, cpu); 211 info.mfn = arbitrary_virt_to_mfn(vcpup); 212 info.offset = offset_in_page(vcpup); 213 214 /* 215 * Check to see if the hypervisor will put the vcpu_info 216 * structure where we want it, which allows direct access via 217 * a percpu-variable. 218 * N.B. This hypercall can _only_ be called once per CPU. 219 * Subsequent calls will error out with -EINVAL. This is due to 220 * the fact that hypervisor has no unregister variant and this 221 * hypercall does not allow to over-write info.mfn and 222 * info.offset. 223 */ 224 err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, 225 xen_vcpu_nr(cpu), &info); 226 227 if (err) { 228 pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n", 229 cpu, err); 230 xen_have_vcpu_info_placement = 0; 231 } else { 232 /* 233 * This cpu is using the registered vcpu info, even if 234 * later ones fail to. 235 */ 236 per_cpu(xen_vcpu, cpu) = vcpup; 237 } 238 } 239 240 if (!xen_have_vcpu_info_placement) 241 xen_vcpu_info_reset(cpu); 242 243 return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0); 244 } 245 246 void xen_reboot(int reason) 247 { 248 struct sched_shutdown r = { .reason = reason }; 249 int cpu; 250 251 for_each_online_cpu(cpu) 252 xen_pmu_finish(cpu); 253 254 if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r)) 255 BUG(); 256 } 257 258 void xen_emergency_restart(void) 259 { 260 xen_reboot(SHUTDOWN_reboot); 261 } 262 263 static int 264 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr) 265 { 266 if (!kexec_crash_loaded()) 267 xen_reboot(SHUTDOWN_crash); 268 return NOTIFY_DONE; 269 } 270 271 static struct notifier_block xen_panic_block = { 272 .notifier_call = xen_panic_event, 273 .priority = INT_MIN 274 }; 275 276 int xen_panic_handler_init(void) 277 { 278 atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block); 279 return 0; 280 } 281 282 void xen_pin_vcpu(int cpu) 283 { 284 static bool disable_pinning; 285 struct sched_pin_override pin_override; 286 int ret; 287 288 if (disable_pinning) 289 return; 290 291 pin_override.pcpu = cpu; 292 ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override); 293 294 /* Ignore errors when removing override. */ 295 if (cpu < 0) 296 return; 297 298 switch (ret) { 299 case -ENOSYS: 300 pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n", 301 cpu); 302 disable_pinning = true; 303 break; 304 case -EPERM: 305 WARN(1, "Trying to pin vcpu without having privilege to do so\n"); 306 disable_pinning = true; 307 break; 308 case -EINVAL: 309 case -EBUSY: 310 pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n", 311 cpu); 312 break; 313 case 0: 314 break; 315 default: 316 WARN(1, "rc %d while trying to pin vcpu\n", ret); 317 disable_pinning = true; 318 } 319 } 320 321 #ifdef CONFIG_HOTPLUG_CPU 322 void xen_arch_register_cpu(int num) 323 { 324 arch_register_cpu(num); 325 } 326 EXPORT_SYMBOL(xen_arch_register_cpu); 327 328 void xen_arch_unregister_cpu(int num) 329 { 330 arch_unregister_cpu(num); 331 } 332 EXPORT_SYMBOL(xen_arch_unregister_cpu); 333 #endif 334