[PATCH v9 07/12] ARM/ARM64: KVM: Emulate PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET

[marc.zyngier@arm.com (Marc Zyngier)]

On Tue, Apr 15 2014 at  7:14:10 am BST, Anup Patel <anup.patel@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@linaro.org>
> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
> Reviewed-by: Christoffer Dall <christoffer.dall@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..b964aa4 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 inline void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)

Loose the "inline". This is not performance critical, and the compiler
does a pretty good job doing that for you.

> +{
> +	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_SUCCESS;
> +		ret = 0;
> +		break;
> +	case PSCI_0_2_FN_SYSTEM_RESET:
> +		kvm_psci_system_reset(vcpu);
> +		val = PSCI_RET_SUCCESS;
> +		ret = 0;
> +		break;

What is the significance of setting val to PSCI_RET_SUCCESS here? We're
exiting to userspace, so surely only the platform emulation can set
that. Am I missing something?

>  	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)
-- 
Jazz is not dead. It just smells funny.