1 // SPDX-License-Identifier: GPL-2.0 2 3 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG 4 #include <linux/memblock.h> 5 #endif 6 #include <linux/cpu.h> 7 #include <linux/kexec.h> 8 #include <linux/slab.h> 9 10 #include <xen/xen.h> 11 #include <xen/features.h> 12 #include <xen/page.h> 13 14 #include <asm/xen/hypercall.h> 15 #include <asm/xen/hypervisor.h> 16 #include <asm/cpu.h> 17 #include <asm/e820/api.h> 18 19 #include "xen-ops.h" 20 #include "smp.h" 21 #include "pmu.h" 22 23 EXPORT_SYMBOL_GPL(hypercall_page); 24 25 /* 26 * Pointer to the xen_vcpu_info structure or 27 * &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info 28 * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info 29 * but if the hypervisor supports VCPUOP_register_vcpu_info then it can point 30 * to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to 31 * acknowledge pending events. 32 * Also more subtly it is used by the patched version of irq enable/disable 33 * e.g. xen_irq_enable_direct and xen_iret in PV mode. 34 * 35 * The desire to be able to do those mask/unmask operations as a single 36 * instruction by using the per-cpu offset held in %gs is the real reason 37 * vcpu info is in a per-cpu pointer and the original reason for this 38 * hypercall. 39 * 40 */ 41 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu); 42 43 /* 44 * Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info 45 * hypercall. This can be used both in PV and PVHVM mode. The structure 46 * overrides the default per_cpu(xen_vcpu, cpu) value. 47 */ 48 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info); 49 50 /* Linux <-> Xen vCPU id mapping */ 51 DEFINE_PER_CPU(uint32_t, xen_vcpu_id); 52 EXPORT_PER_CPU_SYMBOL(xen_vcpu_id); 53 54 enum xen_domain_type xen_domain_type = XEN_NATIVE; 55 EXPORT_SYMBOL_GPL(xen_domain_type); 56 57 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START; 58 EXPORT_SYMBOL(machine_to_phys_mapping); 59 unsigned long machine_to_phys_nr; 60 EXPORT_SYMBOL(machine_to_phys_nr); 61 62 struct start_info *xen_start_info; 63 EXPORT_SYMBOL_GPL(xen_start_info); 64 65 struct shared_info xen_dummy_shared_info; 66 67 __read_mostly int xen_have_vector_callback; 68 EXPORT_SYMBOL_GPL(xen_have_vector_callback); 69 70 /* 71 * NB: needs to live in .data because it's used by xen_prepare_pvh which runs 72 * before clearing the bss. 73 */ 74 uint32_t xen_start_flags __attribute__((section(".data"))) = 0; 75 EXPORT_SYMBOL(xen_start_flags); 76 77 /* 78 * Point at some empty memory to start with. We map the real shared_info 79 * page as soon as fixmap is up and running. 80 */ 81 struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info; 82 83 /* 84 * Flag to determine whether vcpu info placement is available on all 85 * VCPUs. We assume it is to start with, and then set it to zero on 86 * the first failure. This is because it can succeed on some VCPUs 87 * and not others, since it can involve hypervisor memory allocation, 88 * or because the guest failed to guarantee all the appropriate 89 * constraints on all VCPUs (ie buffer can't cross a page boundary). 90 * 91 * Note that any particular CPU may be using a placed vcpu structure, 92 * but we can only optimise if the all are. 93 * 94 * 0: not available, 1: available 95 */ 96 int xen_have_vcpu_info_placement = 1; 97 98 static int xen_cpu_up_online(unsigned int cpu) 99 { 100 xen_init_lock_cpu(cpu); 101 return 0; 102 } 103 104 int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int), 105 int (*cpu_dead_cb)(unsigned int)) 106 { 107 int rc; 108 109 rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE, 110 "x86/xen/guest:prepare", 111 cpu_up_prepare_cb, cpu_dead_cb); 112 if (rc >= 0) { 113 rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, 114 "x86/xen/guest:online", 115 xen_cpu_up_online, NULL); 116 if (rc < 0) 117 cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE); 118 } 119 120 return rc >= 0 ? 0 : rc; 121 } 122 123 static int xen_vcpu_setup_restore(int cpu) 124 { 125 int rc = 0; 126 127 /* Any per_cpu(xen_vcpu) is stale, so reset it */ 128 xen_vcpu_info_reset(cpu); 129 130 /* 131 * For PVH and PVHVM, setup online VCPUs only. The rest will 132 * be handled by hotplug. 133 */ 134 if (xen_pv_domain() || 135 (xen_hvm_domain() && cpu_online(cpu))) { 136 rc = xen_vcpu_setup(cpu); 137 } 138 139 return rc; 140 } 141 142 /* 143 * On restore, set the vcpu placement up again. 144 * If it fails, then we're in a bad state, since 145 * we can't back out from using it... 146 */ 147 void xen_vcpu_restore(void) 148 { 149 int cpu, rc; 150 151 for_each_possible_cpu(cpu) { 152 bool other_cpu = (cpu != smp_processor_id()); 153 bool is_up; 154 155 if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID) 156 continue; 157 158 /* Only Xen 4.5 and higher support this. */ 159 is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up, 160 xen_vcpu_nr(cpu), NULL) > 0; 161 162 if (other_cpu && is_up && 163 HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL)) 164 BUG(); 165 166 if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock)) 167 xen_setup_runstate_info(cpu); 168 169 rc = xen_vcpu_setup_restore(cpu); 170 if (rc) 171 pr_emerg_once("vcpu restore failed for cpu=%d err=%d. " 172 "System will hang.\n", cpu, rc); 173 /* 174 * In case xen_vcpu_setup_restore() fails, do not bring up the 175 * VCPU. This helps us avoid the resulting OOPS when the VCPU 176 * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.) 177 * Note that this does not improve the situation much -- now the 178 * VM hangs instead of OOPSing -- with the VCPUs that did not 179 * fail, spinning in stop_machine(), waiting for the failed 180 * VCPUs to come up. 181 */ 182 if (other_cpu && is_up && (rc == 0) && 183 HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL)) 184 BUG(); 185 } 186 } 187 188 void xen_vcpu_info_reset(int cpu) 189 { 190 if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) { 191 per_cpu(xen_vcpu, cpu) = 192 &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)]; 193 } else { 194 /* Set to NULL so that if somebody accesses it we get an OOPS */ 195 per_cpu(xen_vcpu, cpu) = NULL; 196 } 197 } 198 199 int xen_vcpu_setup(int cpu) 200 { 201 struct vcpu_register_vcpu_info info; 202 int err; 203 struct vcpu_info *vcpup; 204 205 BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); 206 207 /* 208 * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu) 209 * and at restore (xen_vcpu_restore). Also called for hotplugged 210 * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm). 211 * However, the hypercall can only be done once (see below) so if a VCPU 212 * is offlined and comes back online then let's not redo the hypercall. 213 * 214 * For PV it is called during restore (xen_vcpu_restore) and bootup 215 * (xen_setup_vcpu_info_placement). The hotplug mechanism does not 216 * use this function. 217 */ 218 if (xen_hvm_domain()) { 219 if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu)) 220 return 0; 221 } 222 223 if (xen_have_vcpu_info_placement) { 224 vcpup = &per_cpu(xen_vcpu_info, cpu); 225 info.mfn = arbitrary_virt_to_mfn(vcpup); 226 info.offset = offset_in_page(vcpup); 227 228 /* 229 * Check to see if the hypervisor will put the vcpu_info 230 * structure where we want it, which allows direct access via 231 * a percpu-variable. 232 * N.B. This hypercall can _only_ be called once per CPU. 233 * Subsequent calls will error out with -EINVAL. This is due to 234 * the fact that hypervisor has no unregister variant and this 235 * hypercall does not allow to over-write info.mfn and 236 * info.offset. 237 */ 238 err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, 239 xen_vcpu_nr(cpu), &info); 240 241 if (err) { 242 pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n", 243 cpu, err); 244 xen_have_vcpu_info_placement = 0; 245 } else { 246 /* 247 * This cpu is using the registered vcpu info, even if 248 * later ones fail to. 249 */ 250 per_cpu(xen_vcpu, cpu) = vcpup; 251 } 252 } 253 254 if (!xen_have_vcpu_info_placement) 255 xen_vcpu_info_reset(cpu); 256 257 return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0); 258 } 259 260 void xen_reboot(int reason) 261 { 262 struct sched_shutdown r = { .reason = reason }; 263 int cpu; 264 265 for_each_online_cpu(cpu) 266 xen_pmu_finish(cpu); 267 268 if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r)) 269 BUG(); 270 } 271 272 void xen_emergency_restart(void) 273 { 274 xen_reboot(SHUTDOWN_reboot); 275 } 276 277 static int 278 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr) 279 { 280 if (!kexec_crash_loaded()) 281 xen_reboot(SHUTDOWN_crash); 282 return NOTIFY_DONE; 283 } 284 285 static struct notifier_block xen_panic_block = { 286 .notifier_call = xen_panic_event, 287 .priority = INT_MIN 288 }; 289 290 int xen_panic_handler_init(void) 291 { 292 atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block); 293 return 0; 294 } 295 296 void xen_pin_vcpu(int cpu) 297 { 298 static bool disable_pinning; 299 struct sched_pin_override pin_override; 300 int ret; 301 302 if (disable_pinning) 303 return; 304 305 pin_override.pcpu = cpu; 306 ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override); 307 308 /* Ignore errors when removing override. */ 309 if (cpu < 0) 310 return; 311 312 switch (ret) { 313 case -ENOSYS: 314 pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n", 315 cpu); 316 disable_pinning = true; 317 break; 318 case -EPERM: 319 WARN(1, "Trying to pin vcpu without having privilege to do so\n"); 320 disable_pinning = true; 321 break; 322 case -EINVAL: 323 case -EBUSY: 324 pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n", 325 cpu); 326 break; 327 case 0: 328 break; 329 default: 330 WARN(1, "rc %d while trying to pin vcpu\n", ret); 331 disable_pinning = true; 332 } 333 } 334 335 #ifdef CONFIG_HOTPLUG_CPU 336 void xen_arch_register_cpu(int num) 337 { 338 arch_register_cpu(num); 339 } 340 EXPORT_SYMBOL(xen_arch_register_cpu); 341 342 void xen_arch_unregister_cpu(int num) 343 { 344 arch_unregister_cpu(num); 345 } 346 EXPORT_SYMBOL(xen_arch_unregister_cpu); 347 #endif 348