virt/kvm/arm/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/wait.h>
  22
  23 #include <asm/cputype.h>
  24 #include <asm/kvm_emulate.h>
  25 #include <asm/kvm_host.h>
  26
  27 #include <kvm/arm_psci.h>
  28
  29 /*
  30  * This is an implementation of the Power State Coordination Interface
  31  * as described in ARM document number ARM DEN 0022A.
  32  */
  33
  34 #define AFFINITY_MASK(level)    ~((0x1UL << ((level) * MPIDR_LEVEL_BITS)) - 1)
  35
  36 static u32 smccc_get_function(struct kvm_vcpu *vcpu)
  37 {
  38         return vcpu_get_reg(vcpu, 0);
  39 }
  40
  41 static unsigned long smccc_get_arg1(struct kvm_vcpu *vcpu)
  42 {
  43         return vcpu_get_reg(vcpu, 1);
  44 }
  45
  46 static unsigned long smccc_get_arg2(struct kvm_vcpu *vcpu)
  47 {
  48         return vcpu_get_reg(vcpu, 2);
  49 }
  50
  51 static unsigned long smccc_get_arg3(struct kvm_vcpu *vcpu)
  52 {
  53         return vcpu_get_reg(vcpu, 3);
  54 }
  55
  56 static void smccc_set_retval(struct kvm_vcpu *vcpu,
  57                              unsigned long a0,
  58                              unsigned long a1,
  59                              unsigned long a2,
  60                              unsigned long a3)
  61 {
  62         vcpu_set_reg(vcpu, 0, a0);
  63         vcpu_set_reg(vcpu, 1, a1);
  64         vcpu_set_reg(vcpu, 2, a2);
  65         vcpu_set_reg(vcpu, 3, a3);
  66 }
  67
  68 static unsigned long psci_affinity_mask(unsigned long affinity_level)
  69 {
  70         if (affinity_level <= 3)
  71                 return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
  72
  73         return 0;
  74 }
  75
  76 static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
  77 {
  78         /*
  79          * NOTE: For simplicity, we make VCPU suspend emulation to be
  80          * same-as WFI (Wait-for-interrupt) emulation.
  81          *
  82          * This means for KVM the wakeup events are interrupts and
  83          * this is consistent with intended use of StateID as described
  84          * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
  85          *
  86          * Further, we also treat power-down request to be same as
  87          * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
  88          * specification (ARM DEN 0022A). This means all suspend states
  89          * for KVM will preserve the register state.
  90          */
  91         kvm_vcpu_block(vcpu);
  92         kvm_clear_request(KVM_REQ_UNHALT, 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         kvm_make_request(KVM_REQ_SLEEP, vcpu);
 101         kvm_vcpu_kick(vcpu);
 102 }
 103
 104 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
 105 {
 106         struct kvm *kvm = source_vcpu->kvm;
 107         struct kvm_vcpu *vcpu = NULL;
 108         struct swait_queue_head *wq;
 109         unsigned long cpu_id;
 110         unsigned long context_id;
 111         phys_addr_t target_pc;
 112
 113         cpu_id = smccc_get_arg1(source_vcpu) & MPIDR_HWID_BITMASK;
 114         if (vcpu_mode_is_32bit(source_vcpu))
 115                 cpu_id &= ~((u32) 0);
 116
 117         vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
 118
 119         /*
 120          * Make sure the caller requested a valid CPU and that the CPU is
 121          * turned off.
 122          */
 123         if (!vcpu)
 124                 return PSCI_RET_INVALID_PARAMS;
 125         if (!vcpu->arch.power_off) {
 126                 if (kvm_psci_version(source_vcpu, kvm) != KVM_ARM_PSCI_0_1)
 127                         return PSCI_RET_ALREADY_ON;
 128                 else
 129                         return PSCI_RET_INVALID_PARAMS;
 130         }
 131
 132         target_pc = smccc_get_arg2(source_vcpu);
 133         context_id = smccc_get_arg3(source_vcpu);
 134
 135         kvm_reset_vcpu(vcpu);
 136
 137         /* Gracefully handle Thumb2 entry point */
 138         if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
 139                 target_pc &= ~((phys_addr_t) 1);
 140                 vcpu_set_thumb(vcpu);
 141         }
 142
 143         /* Propagate caller endianness */
 144         if (kvm_vcpu_is_be(source_vcpu))
 145                 kvm_vcpu_set_be(vcpu);
 146
 147         *vcpu_pc(vcpu) = target_pc;
 148         /*
 149          * NOTE: We always update r0 (or x0) because for PSCI v0.1
 150          * the general puspose registers are undefined upon CPU_ON.
 151          */
 152         smccc_set_retval(vcpu, context_id, 0, 0, 0);
 153         vcpu->arch.power_off = false;
 154         smp_mb();               /* Make sure the above is visible */
 155
 156         wq = kvm_arch_vcpu_wq(vcpu);
 157         swake_up(wq);
 158
 159         return PSCI_RET_SUCCESS;
 160 }
 161
 162 static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
 163 {
 164         int i, matching_cpus = 0;
 165         unsigned long mpidr;
 166         unsigned long target_affinity;
 167         unsigned long target_affinity_mask;
 168         unsigned long lowest_affinity_level;
 169         struct kvm *kvm = vcpu->kvm;
 170         struct kvm_vcpu *tmp;
 171
 172         target_affinity = smccc_get_arg1(vcpu);
 173         lowest_affinity_level = smccc_get_arg2(vcpu);
 174
 175         /* Determine target affinity mask */
 176         target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
 177         if (!target_affinity_mask)
 178                 return PSCI_RET_INVALID_PARAMS;
 179
 180         /* Ignore other bits of target affinity */
 181         target_affinity &= target_affinity_mask;
 182
 183         /*
 184          * If one or more VCPU matching target affinity are running
 185          * then ON else OFF
 186          */
 187         kvm_for_each_vcpu(i, tmp, kvm) {
 188                 mpidr = kvm_vcpu_get_mpidr_aff(tmp);
 189                 if ((mpidr & target_affinity_mask) == target_affinity) {
 190                         matching_cpus++;
 191                         if (!tmp->arch.power_off)
 192                                 return PSCI_0_2_AFFINITY_LEVEL_ON;
 193                 }
 194         }
 195
 196         if (!matching_cpus)
 197                 return PSCI_RET_INVALID_PARAMS;
 198
 199         return PSCI_0_2_AFFINITY_LEVEL_OFF;
 200 }
 201
 202 static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
 203 {
 204         int i;
 205         struct kvm_vcpu *tmp;
 206
 207         /*
 208          * The KVM ABI specifies that a system event exit may call KVM_RUN
 209          * again and may perform shutdown/reboot at a later time that when the
 210          * actual request is made.  Since we are implementing PSCI and a
 211          * caller of PSCI reboot and shutdown expects that the system shuts
 212          * down or reboots immediately, let's make sure that VCPUs are not run
 213          * after this call is handled and before the VCPUs have been
 214          * re-initialized.
 215          */
 216         kvm_for_each_vcpu(i, tmp, vcpu->kvm)
 217                 tmp->arch.power_off = true;
 218         kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
 219
 220         memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
 221         vcpu->run->system_event.type = type;
 222         vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
 223 }
 224
 225 static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
 226 {
 227         kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
 228 }
 229
 230 static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
 231 {
 232         kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
 233 }
 234
 235 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 236 {
 237         struct kvm *kvm = vcpu->kvm;
 238         u32 psci_fn = smccc_get_function(vcpu);
 239         unsigned long val;
 240         int ret = 1;
 241
 242         switch (psci_fn) {
 243         case PSCI_0_2_FN_PSCI_VERSION:
 244                 /*
 245                  * Bits[31:16] = Major Version = 0
 246                  * Bits[15:0] = Minor Version = 2
 247                  */
 248                 val = KVM_ARM_PSCI_0_2;
 249                 break;
 250         case PSCI_0_2_FN_CPU_SUSPEND:
 251         case PSCI_0_2_FN64_CPU_SUSPEND:
 252                 val = kvm_psci_vcpu_suspend(vcpu);
 253                 break;
 254         case PSCI_0_2_FN_CPU_OFF:
 255                 kvm_psci_vcpu_off(vcpu);
 256                 val = PSCI_RET_SUCCESS;
 257                 break;
 258         case PSCI_0_2_FN_CPU_ON:
 259         case PSCI_0_2_FN64_CPU_ON:
 260                 mutex_lock(&kvm->lock);
 261                 val = kvm_psci_vcpu_on(vcpu);
 262                 mutex_unlock(&kvm->lock);
 263                 break;
 264         case PSCI_0_2_FN_AFFINITY_INFO:
 265         case PSCI_0_2_FN64_AFFINITY_INFO:
 266                 val = kvm_psci_vcpu_affinity_info(vcpu);
 267                 break;
 268         case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
 269                 /*
 270                  * Trusted OS is MP hence does not require migration
 271                  * or
 272                  * Trusted OS is not present
 273                  */
 274                 val = PSCI_0_2_TOS_MP;
 275                 break;
 276         case PSCI_0_2_FN_SYSTEM_OFF:
 277                 kvm_psci_system_off(vcpu);
 278                 /*
 279                  * We should'nt be going back to guest VCPU after
 280                  * receiving SYSTEM_OFF request.
 281                  *
 282                  * If user space accidently/deliberately resumes
 283                  * guest VCPU after SYSTEM_OFF request then guest
 284                  * VCPU should see internal failure from PSCI return
 285                  * value. To achieve this, we preload r0 (or x0) with
 286                  * PSCI return value INTERNAL_FAILURE.
 287                  */
 288                 val = PSCI_RET_INTERNAL_FAILURE;
 289                 ret = 0;
 290                 break;
 291         case PSCI_0_2_FN_SYSTEM_RESET:
 292                 kvm_psci_system_reset(vcpu);
 293                 /*
 294                  * Same reason as SYSTEM_OFF for preloading r0 (or x0)
 295                  * with PSCI return value INTERNAL_FAILURE.
 296                  */
 297                 val = PSCI_RET_INTERNAL_FAILURE;
 298                 ret = 0;
 299                 break;
 300         default:
 301                 val = PSCI_RET_NOT_SUPPORTED;
 302                 break;
 303         }
 304
 305         smccc_set_retval(vcpu, val, 0, 0, 0);
 306         return ret;
 307 }
 308
 309 static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
 310 {
 311         u32 psci_fn = smccc_get_function(vcpu);
 312         u32 feature;
 313         unsigned long val;
 314         int ret = 1;
 315
 316         switch(psci_fn) {
 317         case PSCI_0_2_FN_PSCI_VERSION:
 318                 val = KVM_ARM_PSCI_1_0;
 319                 break;
 320         case PSCI_1_0_FN_PSCI_FEATURES:
 321                 feature = smccc_get_arg1(vcpu);
 322                 switch(feature) {
 323                 case PSCI_0_2_FN_PSCI_VERSION:
 324                 case PSCI_0_2_FN_CPU_SUSPEND:
 325                 case PSCI_0_2_FN64_CPU_SUSPEND:
 326                 case PSCI_0_2_FN_CPU_OFF:
 327                 case PSCI_0_2_FN_CPU_ON:
 328                 case PSCI_0_2_FN64_CPU_ON:
 329                 case PSCI_0_2_FN_AFFINITY_INFO:
 330                 case PSCI_0_2_FN64_AFFINITY_INFO:
 331                 case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
 332                 case PSCI_0_2_FN_SYSTEM_OFF:
 333                 case PSCI_0_2_FN_SYSTEM_RESET:
 334                 case PSCI_1_0_FN_PSCI_FEATURES:
 335                 case ARM_SMCCC_VERSION_FUNC_ID:
 336                         val = 0;
 337                         break;
 338                 default:
 339                         val = PSCI_RET_NOT_SUPPORTED;
 340                         break;
 341                 }
 342                 break;
 343         default:
 344                 return kvm_psci_0_2_call(vcpu);
 345         }
 346
 347         smccc_set_retval(vcpu, val, 0, 0, 0);
 348         return ret;
 349 }
 350
 351 static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
 352 {
 353         struct kvm *kvm = vcpu->kvm;
 354         u32 psci_fn = smccc_get_function(vcpu);
 355         unsigned long val;
 356
 357         switch (psci_fn) {
 358         case KVM_PSCI_FN_CPU_OFF:
 359                 kvm_psci_vcpu_off(vcpu);
 360                 val = PSCI_RET_SUCCESS;
 361                 break;
 362         case KVM_PSCI_FN_CPU_ON:
 363                 mutex_lock(&kvm->lock);
 364                 val = kvm_psci_vcpu_on(vcpu);
 365                 mutex_unlock(&kvm->lock);
 366                 break;
 367         default:
 368                 val = PSCI_RET_NOT_SUPPORTED;
 369                 break;
 370         }
 371
 372         smccc_set_retval(vcpu, val, 0, 0, 0);
 373         return 1;
 374 }
 375
 376 /**
 377  * kvm_psci_call - handle PSCI call if r0 value is in range
 378  * @vcpu: Pointer to the VCPU struct
 379  *
 380  * Handle PSCI calls from guests through traps from HVC instructions.
 381  * The calling convention is similar to SMC calls to the secure world
 382  * where the function number is placed in r0.
 383  *
 384  * This function returns: > 0 (success), 0 (success but exit to user
 385  * space), and < 0 (errors)
 386  *
 387  * Errors:
 388  * -EINVAL: Unrecognized PSCI function
 389  */
 390 static int kvm_psci_call(struct kvm_vcpu *vcpu)
 391 {
 392         switch (kvm_psci_version(vcpu, vcpu->kvm)) {
 393         case KVM_ARM_PSCI_1_0:
 394                 return kvm_psci_1_0_call(vcpu);
 395         case KVM_ARM_PSCI_0_2:
 396                 return kvm_psci_0_2_call(vcpu);
 397         case KVM_ARM_PSCI_0_1:
 398                 return kvm_psci_0_1_call(vcpu);
 399         default:
 400                 return -EINVAL;
 401         };
 402 }
 403
 404 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 405 {
 406         u32 func_id = smccc_get_function(vcpu);
 407         u32 val = PSCI_RET_NOT_SUPPORTED;
 408         u32 feature;
 409
 410         switch (func_id) {
 411         case ARM_SMCCC_VERSION_FUNC_ID:
 412                 val = ARM_SMCCC_VERSION_1_1;
 413                 break;
 414         case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
 415                 feature = smccc_get_arg1(vcpu);
 416                 switch(feature) {
 417                 case ARM_SMCCC_ARCH_WORKAROUND_1:
 418                         if (kvm_arm_harden_branch_predictor())
 419                                 val = 0;
 420                         break;
 421                 }
 422                 break;
 423         default:
 424                 return kvm_psci_call(vcpu);
 425         }
 426
 427         smccc_set_retval(vcpu, val, 0, 0, 0);
 428         return 1;
 429 }