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/kvm_host.h>
  19 #include <linux/wait.h>
  20
  21 #include <asm/kvm_emulate.h>
  22 #include <asm/kvm_psci.h>
  23
  24 /*
  25  * This is an implementation of the Power State Coordination Interface
  26  * as described in ARM document number ARM DEN 0022A.
  27  */
  28
  29 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
  30 {
  31         vcpu->arch.pause = true;
  32 }
  33
  34 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
  35 {
  36         struct kvm *kvm = source_vcpu->kvm;
  37         struct kvm_vcpu *vcpu;
  38         wait_queue_head_t *wq;
  39         unsigned long cpu_id;
  40         phys_addr_t target_pc;
  41
  42         cpu_id = *vcpu_reg(source_vcpu, 1);
  43         if (vcpu_mode_is_32bit(source_vcpu))
  44                 cpu_id &= ~((u32) 0);
  45
  46         if (cpu_id >= atomic_read(&kvm->online_vcpus))
  47                 return KVM_PSCI_RET_INVAL;
  48
  49         target_pc = *vcpu_reg(source_vcpu, 2);
  50
  51         vcpu = kvm_get_vcpu(kvm, cpu_id);
  52
  53         wq = kvm_arch_vcpu_wq(vcpu);
  54         if (!waitqueue_active(wq))
  55                 return KVM_PSCI_RET_INVAL;
  56
  57         kvm_reset_vcpu(vcpu);
  58
  59         /* Gracefully handle Thumb2 entry point */
  60         if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
  61                 target_pc &= ~((phys_addr_t) 1);
  62                 vcpu_set_thumb(vcpu);
  63         }
  64
  65         *vcpu_pc(vcpu) = target_pc;
  66         vcpu->arch.pause = false;
  67         smp_mb();               /* Make sure the above is visible */
  68
  69         wake_up_interruptible(wq);
  70
  71         return KVM_PSCI_RET_SUCCESS;
  72 }
  73
  74 /**
  75  * kvm_psci_call - handle PSCI call if r0 value is in range
  76  * @vcpu: Pointer to the VCPU struct
  77  *
  78  * Handle PSCI calls from guests through traps from HVC instructions.
  79  * The calling convention is similar to SMC calls to the secure world where
  80  * the function number is placed in r0 and this function returns true if the
  81  * function number specified in r0 is withing the PSCI range, and false
  82  * otherwise.
  83  */
  84 bool kvm_psci_call(struct kvm_vcpu *vcpu)
  85 {
  86         unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
  87         unsigned long val;
  88
  89         switch (psci_fn) {
  90         case KVM_PSCI_FN_CPU_OFF:
  91                 kvm_psci_vcpu_off(vcpu);
  92                 val = KVM_PSCI_RET_SUCCESS;
  93                 break;
  94         case KVM_PSCI_FN_CPU_ON:
  95                 val = kvm_psci_vcpu_on(vcpu);
  96                 break;
  97         case KVM_PSCI_FN_CPU_SUSPEND:
  98         case KVM_PSCI_FN_MIGRATE:
  99                 val = KVM_PSCI_RET_NI;
 100                 break;
 101
 102         default:
 103                 return false;
 104         }
 105
 106         *vcpu_reg(vcpu, 0) = val;
 107         return true;
 108 }