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/cputype.h>
  22 #include <asm/kvm_emulate.h>
  23 #include <asm/kvm_psci.h>
  24
  25 /*
  26  * This is an implementation of the Power State Coordination Interface
  27  * as described in ARM document number ARM DEN 0022A.
  28  */
  29
  30 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
  31 {
  32         vcpu->arch.pause = true;
  33 }
  34
  35 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
  36 {
  37         struct kvm *kvm = source_vcpu->kvm;
  38         struct kvm_vcpu *vcpu = NULL, *tmp;
  39         wait_queue_head_t *wq;
  40         unsigned long cpu_id;
  41         unsigned long mpidr;
  42         phys_addr_t target_pc;
  43         int i;
  44
  45         cpu_id = *vcpu_reg(source_vcpu, 1);
  46         if (vcpu_mode_is_32bit(source_vcpu))
  47                 cpu_id &= ~((u32) 0);
  48
  49         kvm_for_each_vcpu(i, tmp, kvm) {
  50                 mpidr = kvm_vcpu_get_mpidr(tmp);
  51                 if ((mpidr & MPIDR_HWID_BITMASK) == (cpu_id & MPIDR_HWID_BITMASK)) {
  52                         vcpu = tmp;
  53                         break;
  54                 }
  55         }
  56
  57         /*
  58          * Make sure the caller requested a valid CPU and that the CPU is
  59          * turned off.
  60          */
  61         if (!vcpu || !vcpu->arch.pause)
  62                 return KVM_PSCI_RET_INVAL;
  63
  64         target_pc = *vcpu_reg(source_vcpu, 2);
  65
  66         kvm_reset_vcpu(vcpu);
  67
  68         /* Gracefully handle Thumb2 entry point */
  69         if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
  70                 target_pc &= ~((phys_addr_t) 1);
  71                 vcpu_set_thumb(vcpu);
  72         }
  73
  74         /* Propagate caller endianness */
  75         if (kvm_vcpu_is_be(source_vcpu))
  76                 kvm_vcpu_set_be(vcpu);
  77
  78         *vcpu_pc(vcpu) = target_pc;
  79         vcpu->arch.pause = false;
  80         smp_mb();               /* Make sure the above is visible */
  81
  82         wq = kvm_arch_vcpu_wq(vcpu);
  83         wake_up_interruptible(wq);
  84
  85         return KVM_PSCI_RET_SUCCESS;
  86 }
  87
  88 /**
  89  * kvm_psci_call - handle PSCI call if r0 value is in range
  90  * @vcpu: Pointer to the VCPU struct
  91  *
  92  * Handle PSCI calls from guests through traps from HVC instructions.
  93  * The calling convention is similar to SMC calls to the secure world where
  94  * the function number is placed in r0 and this function returns true if the
  95  * function number specified in r0 is withing the PSCI range, and false
  96  * otherwise.
  97  */
  98 bool kvm_psci_call(struct kvm_vcpu *vcpu)
  99 {
 100         unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
 101         unsigned long val;
 102
 103         switch (psci_fn) {
 104         case KVM_PSCI_FN_CPU_OFF:
 105                 kvm_psci_vcpu_off(vcpu);
 106                 val = KVM_PSCI_RET_SUCCESS;
 107                 break;
 108         case KVM_PSCI_FN_CPU_ON:
 109                 val = kvm_psci_vcpu_on(vcpu);
 110                 break;
 111         case KVM_PSCI_FN_CPU_SUSPEND:
 112         case KVM_PSCI_FN_MIGRATE:
 113                 val = KVM_PSCI_RET_NI;
 114                 break;
 115
 116         default:
 117                 return false;
 118         }
 119
 120         *vcpu_reg(vcpu, 0) = val;
 121         return true;
 122 }