linux/arch/arm/kvm/psci.c
Marc Zyngier aa024c2f35 KVM: ARM: Power State Coordination Interface implementation
Implement the PSCI specification (ARM DEN 0022A) to control
virtual CPUs being "powered" on or off.

PSCI/KVM is detected using the KVM_CAP_ARM_PSCI capability.

A virtual CPU can now be initialized in a "powered off" state,
using the KVM_ARM_VCPU_POWER_OFF feature flag.

The guest can use either SMC or HVC to execute a PSCI function.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
2013-01-23 13:29:18 -05:00

109 lines
2.7 KiB
C

/*
* Copyright (C) 2012 - ARM Ltd
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/kvm_host.h>
#include <linux/wait.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_psci.h>
/*
* This is an implementation of the Power State Coordination Interface
* as described in ARM document number ARM DEN 0022A.
*/
static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
{
vcpu->arch.pause = true;
}
static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
{
struct kvm *kvm = source_vcpu->kvm;
struct kvm_vcpu *vcpu;
wait_queue_head_t *wq;
unsigned long cpu_id;
phys_addr_t target_pc;
cpu_id = *vcpu_reg(source_vcpu, 1);
if (vcpu_mode_is_32bit(source_vcpu))
cpu_id &= ~((u32) 0);
if (cpu_id >= atomic_read(&kvm->online_vcpus))
return KVM_PSCI_RET_INVAL;
target_pc = *vcpu_reg(source_vcpu, 2);
vcpu = kvm_get_vcpu(kvm, cpu_id);
wq = kvm_arch_vcpu_wq(vcpu);
if (!waitqueue_active(wq))
return KVM_PSCI_RET_INVAL;
kvm_reset_vcpu(vcpu);
/* Gracefully handle Thumb2 entry point */
if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
target_pc &= ~((phys_addr_t) 1);
vcpu_set_thumb(vcpu);
}
*vcpu_pc(vcpu) = target_pc;
vcpu->arch.pause = false;
smp_mb(); /* Make sure the above is visible */
wake_up_interruptible(wq);
return KVM_PSCI_RET_SUCCESS;
}
/**
* kvm_psci_call - handle PSCI call if r0 value is in range
* @vcpu: Pointer to the VCPU struct
*
* Handle PSCI calls from guests through traps from HVC or SMC instructions.
* The calling convention is similar to SMC calls to the secure world where
* the function number is placed in r0 and this function returns true if the
* function number specified in r0 is withing the PSCI range, and false
* otherwise.
*/
bool kvm_psci_call(struct kvm_vcpu *vcpu)
{
unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
unsigned long val;
switch (psci_fn) {
case KVM_PSCI_FN_CPU_OFF:
kvm_psci_vcpu_off(vcpu);
val = KVM_PSCI_RET_SUCCESS;
break;
case KVM_PSCI_FN_CPU_ON:
val = kvm_psci_vcpu_on(vcpu);
break;
case KVM_PSCI_FN_CPU_SUSPEND:
case KVM_PSCI_FN_MIGRATE:
val = KVM_PSCI_RET_NI;
break;
default:
return false;
}
*vcpu_reg(vcpu, 0) = val;
return true;
}