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/preempt.h>
  19 #include <linux/kvm_host.h>
  20 #include <linux/wait.h>
  21
  22 #include <asm/cputype.h>
  23 #include <asm/kvm_emulate.h>
  24 #include <asm/kvm_psci.h>
  25
  26 /*
  27  * This is an implementation of the Power State Coordination Interface
  28  * as described in ARM document number ARM DEN 0022A.
  29  */
  30
  31 #define AFFINITY_MASK(level)    ~((0x1UL << ((level) * MPIDR_LEVEL_BITS)) - 1)
  32
  33 static unsigned long psci_affinity_mask(unsigned long affinity_level)
  34 {
  35         if (affinity_level <= 3)
  36                 return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
  37
  38         return 0;
  39 }
  40
  41 static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
  42 {
  43         /*
  44          * NOTE: For simplicity, we make VCPU suspend emulation to be
  45          * same-as WFI (Wait-for-interrupt) emulation.
  46          *
  47          * This means for KVM the wakeup events are interrupts and
  48          * this is consistent with intended use of StateID as described
  49          * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
  50          *
  51          * Further, we also treat power-down request to be same as
  52          * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
  53          * specification (ARM DEN 0022A). This means all suspend states
  54          * for KVM will preserve the register state.
  55          */
  56         kvm_vcpu_block(vcpu);
  57
  58         return PSCI_RET_SUCCESS;
  59 }
  60
  61 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
  62 {
  63         vcpu->arch.pause = true;
  64 }
  65
  66 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
  67 {
  68         struct kvm *kvm = source_vcpu->kvm;
  69         struct kvm_vcpu *vcpu = NULL, *tmp;
  70         wait_queue_head_t *wq;
  71         unsigned long cpu_id;
  72         unsigned long context_id;
  73         unsigned long mpidr;
  74         phys_addr_t target_pc;
  75         int i;
  76
  77         cpu_id = *vcpu_reg(source_vcpu, 1);
  78         if (vcpu_mode_is_32bit(source_vcpu))
  79                 cpu_id &= ~((u32) 0);
  80
  81         kvm_for_each_vcpu(i, tmp, kvm) {
  82                 mpidr = kvm_vcpu_get_mpidr(tmp);
  83                 if ((mpidr & MPIDR_HWID_BITMASK) == (cpu_id & MPIDR_HWID_BITMASK)) {
  84                         vcpu = tmp;
  85                         break;
  86                 }
  87         }
  88
  89         /*
  90          * Make sure the caller requested a valid CPU and that the CPU is
  91          * turned off.
  92          */
  93         if (!vcpu)
  94                 return PSCI_RET_INVALID_PARAMS;
  95         if (!vcpu->arch.pause) {
  96                 if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1)
  97                         return PSCI_RET_ALREADY_ON;
  98                 else
  99                         return PSCI_RET_INVALID_PARAMS;
 100         }
 101
 102         target_pc = *vcpu_reg(source_vcpu, 2);
 103         context_id = *vcpu_reg(source_vcpu, 3);
 104
 105         kvm_reset_vcpu(vcpu);
 106
 107         /* Gracefully handle Thumb2 entry point */
 108         if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
 109                 target_pc &= ~((phys_addr_t) 1);
 110                 vcpu_set_thumb(vcpu);
 111         }
 112
 113         /* Propagate caller endianness */
 114         if (kvm_vcpu_is_be(source_vcpu))
 115                 kvm_vcpu_set_be(vcpu);
 116
 117         *vcpu_pc(vcpu) = target_pc;
 118         /*
 119          * NOTE: We always update r0 (or x0) because for PSCI v0.1
 120          * the general puspose registers are undefined upon CPU_ON.
 121          */
 122         *vcpu_reg(vcpu, 0) = context_id;
 123         vcpu->arch.pause = false;
 124         smp_mb();               /* Make sure the above is visible */
 125
 126         wq = kvm_arch_vcpu_wq(vcpu);
 127         wake_up_interruptible(wq);
 128
 129         return PSCI_RET_SUCCESS;
 130 }
 131
 132 static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
 133 {
 134         int i;
 135         unsigned long mpidr;
 136         unsigned long target_affinity;
 137         unsigned long target_affinity_mask;
 138         unsigned long lowest_affinity_level;
 139         struct kvm *kvm = vcpu->kvm;
 140         struct kvm_vcpu *tmp;
 141
 142         target_affinity = *vcpu_reg(vcpu, 1);
 143         lowest_affinity_level = *vcpu_reg(vcpu, 2);
 144
 145         /* Determine target affinity mask */
 146         target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
 147         if (!target_affinity_mask)
 148                 return PSCI_RET_INVALID_PARAMS;
 149
 150         /* Ignore other bits of target affinity */
 151         target_affinity &= target_affinity_mask;
 152
 153         /*
 154          * If one or more VCPU matching target affinity are running
 155          * then ON else OFF
 156          */
 157         kvm_for_each_vcpu(i, tmp, kvm) {
 158                 mpidr = kvm_vcpu_get_mpidr(tmp);
 159                 if (((mpidr & target_affinity_mask) == target_affinity) &&
 160                     !tmp->arch.pause) {
 161                         return PSCI_0_2_AFFINITY_LEVEL_ON;
 162                 }
 163         }
 164
 165         return PSCI_0_2_AFFINITY_LEVEL_OFF;
 166 }
 167
 168 static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
 169 {
 170         int i;
 171         struct kvm_vcpu *tmp;
 172
 173         /*
 174          * The KVM ABI specifies that a system event exit may call KVM_RUN
 175          * again and may perform shutdown/reboot at a later time that when the
 176          * actual request is made.  Since we are implementing PSCI and a
 177          * caller of PSCI reboot and shutdown expects that the system shuts
 178          * down or reboots immediately, let's make sure that VCPUs are not run
 179          * after this call is handled and before the VCPUs have been
 180          * re-initialized.
 181          */
 182         kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
 183                 tmp->arch.pause = true;
 184                 kvm_vcpu_kick(tmp);
 185         }
 186
 187         memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
 188         vcpu->run->system_event.type = type;
 189         vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
 190 }
 191
 192 static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
 193 {
 194         kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
 195 }
 196
 197 static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
 198 {
 199         kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
 200 }
 201
 202 int kvm_psci_version(struct kvm_vcpu *vcpu)
 203 {
 204         if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
 205                 return KVM_ARM_PSCI_0_2;
 206
 207         return KVM_ARM_PSCI_0_1;
 208 }
 209
 210 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
 211 {
 212         int ret = 1;
 213         unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
 214         unsigned long val;
 215
 216         switch (psci_fn) {
 217         case PSCI_0_2_FN_PSCI_VERSION:
 218                 /*
 219                  * Bits[31:16] = Major Version = 0
 220                  * Bits[15:0] = Minor Version = 2
 221                  */
 222                 val = 2;
 223                 break;
 224         case PSCI_0_2_FN_CPU_SUSPEND:
 225         case PSCI_0_2_FN64_CPU_SUSPEND:
 226                 val = kvm_psci_vcpu_suspend(vcpu);
 227                 break;
 228         case PSCI_0_2_FN_CPU_OFF:
 229                 kvm_psci_vcpu_off(vcpu);
 230                 val = PSCI_RET_SUCCESS;
 231                 break;
 232         case PSCI_0_2_FN_CPU_ON:
 233         case PSCI_0_2_FN64_CPU_ON:
 234                 val = kvm_psci_vcpu_on(vcpu);
 235                 break;
 236         case PSCI_0_2_FN_AFFINITY_INFO:
 237         case PSCI_0_2_FN64_AFFINITY_INFO:
 238                 val = kvm_psci_vcpu_affinity_info(vcpu);
 239                 break;
 240         case PSCI_0_2_FN_MIGRATE:
 241         case PSCI_0_2_FN64_MIGRATE:
 242                 val = PSCI_RET_NOT_SUPPORTED;
 243                 break;
 244         case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
 245                 /*
 246                  * Trusted OS is MP hence does not require migration
 247                  * or
 248                  * Trusted OS is not present
 249                  */
 250                 val = PSCI_0_2_TOS_MP;
 251                 break;
 252         case PSCI_0_2_FN_MIGRATE_INFO_UP_CPU:
 253         case PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU:
 254                 val = PSCI_RET_NOT_SUPPORTED;
 255                 break;
 256         case PSCI_0_2_FN_SYSTEM_OFF:
 257                 kvm_psci_system_off(vcpu);
 258                 /*
 259                  * We should'nt be going back to guest VCPU after
 260                  * receiving SYSTEM_OFF request.
 261                  *
 262                  * If user space accidently/deliberately resumes
 263                  * guest VCPU after SYSTEM_OFF request then guest
 264                  * VCPU should see internal failure from PSCI return
 265                  * value. To achieve this, we preload r0 (or x0) with
 266                  * PSCI return value INTERNAL_FAILURE.
 267                  */
 268                 val = PSCI_RET_INTERNAL_FAILURE;
 269                 ret = 0;
 270                 break;
 271         case PSCI_0_2_FN_SYSTEM_RESET:
 272                 kvm_psci_system_reset(vcpu);
 273                 /*
 274                  * Same reason as SYSTEM_OFF for preloading r0 (or x0)
 275                  * with PSCI return value INTERNAL_FAILURE.
 276                  */
 277                 val = PSCI_RET_INTERNAL_FAILURE;
 278                 ret = 0;
 279                 break;
 280         default:
 281                 return -EINVAL;
 282         }
 283
 284         *vcpu_reg(vcpu, 0) = val;
 285         return ret;
 286 }
 287
 288 static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
 289 {
 290         unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
 291         unsigned long val;
 292
 293         switch (psci_fn) {
 294         case KVM_PSCI_FN_CPU_OFF:
 295                 kvm_psci_vcpu_off(vcpu);
 296                 val = PSCI_RET_SUCCESS;
 297                 break;
 298         case KVM_PSCI_FN_CPU_ON:
 299                 val = kvm_psci_vcpu_on(vcpu);
 300                 break;
 301         case KVM_PSCI_FN_CPU_SUSPEND:
 302         case KVM_PSCI_FN_MIGRATE:
 303                 val = PSCI_RET_NOT_SUPPORTED;
 304                 break;
 305         default:
 306                 return -EINVAL;
 307         }
 308
 309         *vcpu_reg(vcpu, 0) = val;
 310         return 1;
 311 }
 312
 313 /**
 314  * kvm_psci_call - handle PSCI call if r0 value is in range
 315  * @vcpu: Pointer to the VCPU struct
 316  *
 317  * Handle PSCI calls from guests through traps from HVC instructions.
 318  * The calling convention is similar to SMC calls to the secure world
 319  * where the function number is placed in r0.
 320  *
 321  * This function returns: > 0 (success), 0 (success but exit to user
 322  * space), and < 0 (errors)
 323  *
 324  * Errors:
 325  * -EINVAL: Unrecognized PSCI function
 326  */
 327 int kvm_psci_call(struct kvm_vcpu *vcpu)
 328 {
 329         switch (kvm_psci_version(vcpu)) {
 330         case KVM_ARM_PSCI_0_2:
 331                 return kvm_psci_0_2_call(vcpu);
 332         case KVM_ARM_PSCI_0_1:
 333                 return kvm_psci_0_1_call(vcpu);
 334         default:
 335                 return -EINVAL;
 336         };
 337 }