[PATCH v10 07/12] ARM/ARM64: KVM: Emulate PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET

[Anup Patel]

On Mon, Apr 28, 2014 at 8:04 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
> On Mon, Apr 21 2014 at  2:00:01 pm BST, Anup Patel <anup.patel at linaro.org> wrote:
>> The PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET functions are system-level
>> functions hence cannot be fully emulated by in-kernel PSCI emulation code.
>>
>> To tackle this, we forward PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET function
>> calls from vcpu to user space (i.e. QEMU or KVMTOOL) via kvm_run structure
>> using KVM_EXIT_SYSTEM_EVENT exit reasons.
>>
>> Signed-off-by: Anup Patel <anup.patel at linaro.org>
>> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar at linaro.org>
>> Reviewed-by: Christoffer Dall <christoffer.dall at linaro.org>
>> ---
>>  arch/arm/kvm/psci.c |   32 +++++++++++++++++++++++++++++---
>>  1 file changed, 29 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
>> index 14e6fa6..4486d0f 100644
>> --- a/arch/arm/kvm/psci.c
>> +++ b/arch/arm/kvm/psci.c
>> @@ -85,6 +85,23 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
>>       return PSCI_RET_SUCCESS;
>>  }
>>
>> +static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
>> +{
>> +     memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
>> +     vcpu->run->system_event.type = type;
>> +     vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
>> +}
>> +
>> +static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
>> +{
>> +     kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
>> +}
>> +
>> +static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
>> +{
>> +     kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
>> +}
>> +
>>  int kvm_psci_version(struct kvm_vcpu *vcpu)
>>  {
>>       if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
>> @@ -95,6 +112,7 @@ int kvm_psci_version(struct kvm_vcpu *vcpu)
>>
>>  static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
>>  {
>> +     int ret = 1;
>>       unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
>>       unsigned long val;
>>
>> @@ -114,13 +132,21 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
>>       case PSCI_0_2_FN64_CPU_ON:
>>               val = kvm_psci_vcpu_on(vcpu);
>>               break;
>> +     case PSCI_0_2_FN_SYSTEM_OFF:
>> +             kvm_psci_system_off(vcpu);
>> +             val = PSCI_RET_INTERNAL_FAILURE;
>> +             ret = 0;
>> +             break;
>> +     case PSCI_0_2_FN_SYSTEM_RESET:
>> +             kvm_psci_system_reset(vcpu);
>> +             val = PSCI_RET_INTERNAL_FAILURE;
>> +             ret = 0;
>> +             break;
>
> Maybe add a comment about why we set INTERNAL_FAILURE here (we shouldn't
> be able to come back from such a PSCI call).

OK, I will add a comment about INTERNAL_FAILURE.

>
>>       case PSCI_0_2_FN_CPU_SUSPEND:
>>       case PSCI_0_2_FN_AFFINITY_INFO:
>>       case PSCI_0_2_FN_MIGRATE:
>>       case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
>>       case PSCI_0_2_FN_MIGRATE_INFO_UP_CPU:
>> -     case PSCI_0_2_FN_SYSTEM_OFF:
>> -     case PSCI_0_2_FN_SYSTEM_RESET:
>>       case PSCI_0_2_FN64_CPU_SUSPEND:
>>       case PSCI_0_2_FN64_AFFINITY_INFO:
>>       case PSCI_0_2_FN64_MIGRATE:
>> @@ -132,7 +158,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
>>       }
>>
>>       *vcpu_reg(vcpu, 0) = val;
>> -     return 1;
>> +     return ret;
>>  }
>>
>>  static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
>
> Aside from this minor comment:
>
> Acked-by: Marc Zyngier <marc.zyngier at arm.com>
>
>         M.
> --
> Jazz is not dead. It just smells funny.
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--
Anup