arch/arm/kvm/psci.c

   1 /*
   2  * Copyright (C) 2012 - ARM Ltd
   3  * Author: Marc Zyngier <marc.zyngier@arm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <linux/arm-smccc.h>
  19 #include <linux/preempt.h>
  20 #include <linux/kvm_host.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/wait.h>
  23
  24 #include <asm/cputype.h>
  25 #include <asm/kvm_emulate.h>
  26 #include <asm/kvm_host.h>
  27
  28 #include <kvm/arm_psci.h>
  29
  30 /*
  31  * This is an implementation of the Power State Coordination Interface
  32  * as described in ARM document number ARM DEN 0022A.
  33  */
  34
  35 #define AFFINITY_MASK(level)    ~((0x1UL << ((level) * MPIDR_LEVEL_BITS)) - 1)
  36
  37 static u32 smccc_get_function(struct kvm_vcpu *vcpu)
  38 {
  39         return vcpu_get_reg(vcpu, 0);
  40 }
  41
  42 static unsigned long smccc_get_arg1(struct kvm_vcpu *vcpu)
  43 {
  44         return vcpu_get_reg(vcpu, 1);
  45 }
  46
  47 static unsigned long smccc_get_arg2(struct kvm_vcpu *vcpu)
  48 {
  49         return vcpu_get_reg(vcpu, 2);
  50 }
  51
  52 static unsigned long smccc_get_arg3(struct kvm_vcpu *vcpu)
  53 {
  54         return vcpu_get_reg(vcpu, 3);
  55 }
  56
  57 static void smccc_set_retval(struct kvm_vcpu *vcpu,
  58                              unsigned long a0,
  59                              unsigned long a1,
  60                              unsigned long a2,
  61                              unsigned long a3)
  62 {
  63         vcpu_set_reg(vcpu, 0, a0);
  64         vcpu_set_reg(vcpu, 1, a1);
  65         vcpu_set_reg(vcpu, 2, a2);
  66         vcpu_set_reg(vcpu, 3, a3);
  67 }
  68
  69 static unsigned long psci_affinity_mask(unsigned long affinity_level)
  70 {
  71         if (affinity_level <= 3)
  72                 return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
  73
  74         return 0;
  75 }
  76
  77 static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
  78 {
  79         /*
  80          * NOTE: For simplicity, we make VCPU suspend emulation to be
  81          * same-as WFI (Wait-for-interrupt) emulation.
  82          *
  83          * This means for KVM the wakeup events are interrupts and
  84          * this is consistent with intended use of StateID as described
  85          * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
  86          *
  87          * Further, we also treat power-down request to be same as
  88          * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
  89          * specification (ARM DEN 0022A). This means all suspend states
  90          * for KVM will preserve the register state.
  91          */
  92         kvm_vcpu_block(vcpu);
  93
  94         return PSCI_RET_SUCCESS;
  95 }
  96
  97 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
  98 {
  99         vcpu->arch.power_off = true;
 100 }
 101
 102 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
 103 {
 104         struct kvm *kvm = source_vcpu->kvm;
 105         struct kvm_vcpu *vcpu = NULL;
 106         struct swait_queue_head *wq;
 107         unsigned long cpu_id;
 108         unsigned long context_id;
 109         phys_addr_t target_pc;
 110
 111         cpu_id = smccc_get_arg1(source_vcpu) & MPIDR_HWID_BITMASK;
 112         if (vcpu_mode_is_32bit(source_vcpu))
 113                 cpu_id &= ~((u32) 0);
 114
 115         vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
 116
 117         /*
 118          * Make sure the caller requested a valid CPU and that the CPU is
 119          * turned off.
 120          */
 121         if (!vcpu)
 122                 return PSCI_RET_INVALID_PARAMS;
 123         if (!vcpu->arch.power_off) {
 124                 if (kvm_psci_version(source_vcpu, kvm) != KVM_ARM_PSCI_0_1)
 125                         return PSCI_RET_ALREADY_ON;
 126                 else
 127                         return PSCI_RET_INVALID_PARAMS;
 128         }
 129
 130         target_pc = smccc_get_arg2(source_vcpu);
 131         context_id = smccc_get_arg3(source_vcpu);
 132
 133         kvm_reset_vcpu(vcpu);
 134
 135         /* Gracefully handle Thumb2 entry point */
 136         if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
 137                 target_pc &= ~((phys_addr_t) 1);
 138                 vcpu_set_thumb(vcpu);
 139         }
 140
 141         /* Propagate caller endianness */
 142         if (kvm_vcpu_is_be(source_vcpu))
 143                 kvm_vcpu_set_be(vcpu);
 144
 145         *vcpu_pc(vcpu) = target_pc;
 146         /*
 147          * NOTE: We always update r0 (or x0) because for PSCI v0.1
 148          * the general puspose registers are undefined upon CPU_ON.
 149          */
 150         smccc_set_retval(vcpu, context_id, 0, 0, 0);
 151         vcpu->arch.power_off = false;
 152         smp_mb();               /* Make sure the above is visible */
 153
 154         wq = kvm_arch_vcpu_wq(vcpu);
 155         swake_up(wq);
 156
 157         return PSCI_RET_SUCCESS;
 158 }
 159
 160 static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
 161 {
 162         int i, matching_cpus = 0;
 163         unsigned long mpidr;
 164         unsigned long target_affinity;
 165         unsigned long target_affinity_mask;
 166         unsigned long lowest_affinity_level;
 167         struct kvm *kvm = vcpu->kvm;
 168         struct kvm_vcpu *tmp;
 169
 170         target_affinity = smccc_get_arg1(vcpu);
 171         lowest_affinity_level = smccc_get_arg2(vcpu);
 172
 173         /* Determine target affinity mask */
 174         target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
 175         if (!target_affinity_mask)
 176                 return PSCI_RET_INVALID_PARAMS;
 177
 178         /* Ignore other bits of target affinity */
 179         target_affinity &= target_affinity_mask;
 180
 181         /*
 182          * If one or more VCPU matching target affinity are running
 183          * then ON else OFF
 184          */
 185         kvm_for_each_vcpu(i, tmp, kvm) {
 186                 mpidr = kvm_vcpu_get_mpidr_aff(tmp);
 187                 if ((mpidr & target_affinity_mask) == target_affinity) {
 188                         matching_cpus++;
 189                         if (!tmp->arch.power_off)
 190                                 return PSCI_0_2_AFFINITY_LEVEL_ON;
 191                 }
 192         }
 193
 194         if (!matching_cpus)
 195                 return PSCI_RET_INVALID_PARAMS;
 196
 197         return PSCI_0_2_AFFINITY_LEVEL_OFF;
 198 }
 199
 200 static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
 201 {
 202         int i;
 203         struct kvm_vcpu *tmp;
 204
 205         /*
 206          * The KVM ABI specifies that a system event exit may call KVM_RUN
 207          * again and may perform shutdown/reboot at a later time that when the
 208          * actual request is made.  Since we are implementing PSCI and a
 209          * caller of PSCI reboot and shutdown expects that the system shuts
 210          * down or reboots immediately, let's make sure that VCPUs are not run
 211          * after this call is handled and before the VCPUs have been
 212          * re-initialized.
 213          */
 214         kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
 215                 tmp->arch.power_off = true;
 216                 kvm_vcpu_kick(tmp);
 217         }
 218
 219         memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
 220         vcpu->run->system_event.type = type;
 221         vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
 222 }
 223
 224 static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
 225 {
 226         kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
 227 }
 228
 229 static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
 230 {
 231         kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
 232 }
 233
 234 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 235 {
 236         struct kvm *kvm = vcpu->kvm;
 237         unsigned long psci_fn = smccc_get_function(vcpu);
 238         unsigned long val;
 239         int ret = 1;
 240
 241         switch (psci_fn) {
 242         case PSCI_0_2_FN_PSCI_VERSION:
 243                 /*
 244                  * Bits[31:16] = Major Version = 0
 245                  * Bits[15:0] = Minor Version = 2
 246                  */
 247                 val = KVM_ARM_PSCI_0_2;
 248                 break;
 249         case PSCI_0_2_FN_CPU_SUSPEND:
 250         case PSCI_0_2_FN64_CPU_SUSPEND:
 251                 val = kvm_psci_vcpu_suspend(vcpu);
 252                 break;
 253         case PSCI_0_2_FN_CPU_OFF:
 254                 kvm_psci_vcpu_off(vcpu);
 255                 val = PSCI_RET_SUCCESS;
 256                 break;
 257         case PSCI_0_2_FN_CPU_ON:
 258         case PSCI_0_2_FN64_CPU_ON:
 259                 mutex_lock(&kvm->lock);
 260                 val = kvm_psci_vcpu_on(vcpu);
 261                 mutex_unlock(&kvm->lock);
 262                 break;
 263         case PSCI_0_2_FN_AFFINITY_INFO:
 264         case PSCI_0_2_FN64_AFFINITY_INFO:
 265                 val = kvm_psci_vcpu_affinity_info(vcpu);
 266                 break;
 267         case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
 268                 /*
 269                  * Trusted OS is MP hence does not require migration
 270                  * or
 271                  * Trusted OS is not present
 272                  */
 273                 val = PSCI_0_2_TOS_MP;
 274                 break;
 275         case PSCI_0_2_FN_SYSTEM_OFF:
 276                 kvm_psci_system_off(vcpu);
 277                 /*
 278                  * We should'nt be going back to guest VCPU after
 279                  * receiving SYSTEM_OFF request.
 280                  *
 281                  * If user space accidently/deliberately resumes
 282                  * guest VCPU after SYSTEM_OFF request then guest
 283                  * VCPU should see internal failure from PSCI return
 284                  * value. To achieve this, we preload r0 (or x0) with
 285                  * PSCI return value INTERNAL_FAILURE.
 286                  */
 287                 val = PSCI_RET_INTERNAL_FAILURE;
 288                 ret = 0;
 289                 break;
 290         case PSCI_0_2_FN_SYSTEM_RESET:
 291                 kvm_psci_system_reset(vcpu);
 292                 /*
 293                  * Same reason as SYSTEM_OFF for preloading r0 (or x0)
 294                  * with PSCI return value INTERNAL_FAILURE.
 295                  */
 296                 val = PSCI_RET_INTERNAL_FAILURE;
 297                 ret = 0;
 298                 break;
 299         default:
 300                 val = PSCI_RET_NOT_SUPPORTED;
 301                 break;
 302         }
 303
 304         smccc_set_retval(vcpu, val, 0, 0, 0);
 305         return ret;
 306 }
 307
 308 static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
 309 {
 310         u32 psci_fn = smccc_get_function(vcpu);
 311         u32 feature;
 312         unsigned long val;
 313         int ret = 1;
 314
 315         switch(psci_fn) {
 316         case PSCI_0_2_FN_PSCI_VERSION:
 317                 val = KVM_ARM_PSCI_1_0;
 318                 break;
 319         case PSCI_1_0_FN_PSCI_FEATURES:
 320                 feature = smccc_get_arg1(vcpu);
 321                 switch(feature) {
 322                 case PSCI_0_2_FN_PSCI_VERSION:
 323                 case PSCI_0_2_FN_CPU_SUSPEND:
 324                 case PSCI_0_2_FN64_CPU_SUSPEND:
 325                 case PSCI_0_2_FN_CPU_OFF:
 326                 case PSCI_0_2_FN_CPU_ON:
 327                 case PSCI_0_2_FN64_CPU_ON:
 328                 case PSCI_0_2_FN_AFFINITY_INFO:
 329                 case PSCI_0_2_FN64_AFFINITY_INFO:
 330                 case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
 331                 case PSCI_0_2_FN_SYSTEM_OFF:
 332                 case PSCI_0_2_FN_SYSTEM_RESET:
 333                 case PSCI_1_0_FN_PSCI_FEATURES:
 334                 case ARM_SMCCC_VERSION_FUNC_ID:
 335                         val = 0;
 336                         break;
 337                 default:
 338                         val = PSCI_RET_NOT_SUPPORTED;
 339                         break;
 340                 }
 341                 break;
 342         default:
 343                 return kvm_psci_0_2_call(vcpu);
 344         }
 345
 346         smccc_set_retval(vcpu, val, 0, 0, 0);
 347         return ret;
 348 }
 349
 350 static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
 351 {
 352         struct kvm *kvm = vcpu->kvm;
 353         unsigned long psci_fn = smccc_get_function(vcpu);
 354         unsigned long val;
 355
 356         switch (psci_fn) {
 357         case KVM_PSCI_FN_CPU_OFF:
 358                 kvm_psci_vcpu_off(vcpu);
 359                 val = PSCI_RET_SUCCESS;
 360                 break;
 361         case KVM_PSCI_FN_CPU_ON:
 362                 mutex_lock(&kvm->lock);
 363                 val = kvm_psci_vcpu_on(vcpu);
 364                 mutex_unlock(&kvm->lock);
 365                 break;
 366         default:
 367                 val = PSCI_RET_NOT_SUPPORTED;
 368                 break;
 369         }
 370
 371         smccc_set_retval(vcpu, val, 0, 0, 0);
 372         return 1;
 373 }
 374
 375 /**
 376  * kvm_psci_call - handle PSCI call if r0 value is in range
 377  * @vcpu: Pointer to the VCPU struct
 378  *
 379  * Handle PSCI calls from guests through traps from HVC instructions.
 380  * The calling convention is similar to SMC calls to the secure world
 381  * where the function number is placed in r0.
 382  *
 383  * This function returns: > 0 (success), 0 (success but exit to user
 384  * space), and < 0 (errors)
 385  *
 386  * Errors:
 387  * -EINVAL: Unrecognized PSCI function
 388  */
 389 static int kvm_psci_call(struct kvm_vcpu *vcpu)
 390 {
 391         switch (kvm_psci_version(vcpu, vcpu->kvm)) {
 392         case KVM_ARM_PSCI_1_0:
 393                 return kvm_psci_1_0_call(vcpu);
 394         case KVM_ARM_PSCI_0_2:
 395                 return kvm_psci_0_2_call(vcpu);
 396         case KVM_ARM_PSCI_0_1:
 397                 return kvm_psci_0_1_call(vcpu);
 398         default:
 399                 return -EINVAL;
 400         };
 401 }
 402
 403 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 404 {
 405         u32 func_id = smccc_get_function(vcpu);
 406         u32 val = SMCCC_RET_NOT_SUPPORTED;
 407         u32 feature;
 408
 409         switch (func_id) {
 410         case ARM_SMCCC_VERSION_FUNC_ID:
 411                 val = ARM_SMCCC_VERSION_1_1;
 412                 break;
 413         case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
 414                 feature = smccc_get_arg1(vcpu);
 415                 switch(feature) {
 416                 case ARM_SMCCC_ARCH_WORKAROUND_1:
 417                         if (kvm_arm_harden_branch_predictor())
 418                                 val = SMCCC_RET_SUCCESS;
 419                         break;
 420                 case ARM_SMCCC_ARCH_WORKAROUND_2:
 421                         switch (kvm_arm_have_ssbd()) {
 422                         case KVM_SSBD_FORCE_DISABLE:
 423                         case KVM_SSBD_UNKNOWN:
 424                                 break;
 425                         case KVM_SSBD_KERNEL:
 426                                 val = SMCCC_RET_SUCCESS;
 427                                 break;
 428                         case KVM_SSBD_FORCE_ENABLE:
 429                         case KVM_SSBD_MITIGATED:
 430                                 val = SMCCC_RET_NOT_REQUIRED;
 431                                 break;
 432                         }
 433                         break;
 434                 }
 435                 break;
 436         default:
 437                 return kvm_psci_call(vcpu);
 438         }
 439
 440         smccc_set_retval(vcpu, val, 0, 0, 0);
 441         return 1;
 442 }
 443
 444 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
 445 {
 446         return 1;               /* PSCI version */
 447 }
 448
 449 int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
 450 {
 451         if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices))
 452                 return -EFAULT;
 453
 454         return 0;
 455 }
 456
 457 int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 458 {
 459         if (reg->id == KVM_REG_ARM_PSCI_VERSION) {
 460                 void __user *uaddr = (void __user *)(long)reg->addr;
 461                 u64 val;
 462
 463                 val = kvm_psci_version(vcpu, vcpu->kvm);
 464                 if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
 465                         return -EFAULT;
 466
 467                 return 0;
 468         }
 469
 470         return -EINVAL;
 471 }
 472
 473 int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 474 {
 475         if (reg->id == KVM_REG_ARM_PSCI_VERSION) {
 476                 void __user *uaddr = (void __user *)(long)reg->addr;
 477                 bool wants_02;
 478                 u64 val;
 479
 480                 if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
 481                         return -EFAULT;
 482
 483                 wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
 484
 485                 switch (val) {
 486                 case KVM_ARM_PSCI_0_1:
 487                         if (wants_02)
 488                                 return -EINVAL;
 489                         vcpu->kvm->arch.psci_version = val;
 490                         return 0;
 491                 case KVM_ARM_PSCI_0_2:
 492                 case KVM_ARM_PSCI_1_0:
 493                         if (!wants_02)
 494                                 return -EINVAL;
 495                         vcpu->kvm->arch.psci_version = val;
 496                         return 0;
 497                 }
 498         }
 499
 500         return -EINVAL;
 501 }