On Mon, Apr 21, 2014 at 06:30:05PM +0530, Anup Patel wrote:
> This patch adds emulation of PSCI v0.2 CPU_SUSPEND function call for
> KVM ARM/ARM64. This is a CPU-level function call which can suspend
> current CPU or current CPU cluster. We don't have VCPU clusters in
> KVM so we only suspend the current VCPU.
>
> The CPU_SUSPEND emulation is not tested much because currently there
> is no CPUIDLE driver in Linux kernel that uses PSCI CPU_SUSPEND. The
> PSCI CPU_SUSPEND implementation in ARM64 kernel was tested using a
> Simple CPUIDLE driver which is not published due to unstable DT-bindings
> for PSCI.
> (For more info, http://lwn.net/Articles/574950/)
>
> For simplicity, we implement CPU_SUSPEND emulation similar to WFI
> (Wait-for-interrupt) emulation and we also treat power-down request
> to be same as stand-by request. This is consistent with section
> 5.4.1 and section 5.4.2 of PSCI v0.2 specification.
>
> Signed-off-by: Anup Patel <[email protected]>
> Signed-off-by: Pranavkumar Sawargaonkar <[email protected]>
> ---
> arch/arm/kvm/psci.c | 28 ++++++++++++++++++++++++----
> 1 file changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
> index b582e99..757e506 100644
> --- a/arch/arm/kvm/psci.c
> +++ b/arch/arm/kvm/psci.c
> @@ -37,6 +37,26 @@ static unsigned long psci_affinity_mask(unsigned long
> affinity_level)
> return 0;
> }
>
> +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
> +{
> + /*
> + * NOTE: For simplicity, we make VCPU suspend emulation to be
> + * same-as WFI (Wait-for-interrupt) emulation.
> + *
> + * This means for KVM the wakeup events are interrupts and
> + * this is consistent with intended use of StateID as described
> + * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
> + *
> + * Further, we also treat power-down request to be same as
> + * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
> + * specification (ARM DEN 0022A). This means all suspend states
> + * for KVM will preserve the register state.
> + */
> + kvm_vcpu_block(vcpu);
> +
> + return PSCI_RET_SUCCESS;
> +}
> +
> static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
> {
> vcpu->arch.pause = true;
> @@ -183,6 +203,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
> */
> val = 2;
> break;
> + case PSCI_0_2_FN_CPU_SUSPEND:
> + case PSCI_0_2_FN64_CPU_SUSPEND:
> + val = kvm_psci_vcpu_suspend(vcpu);
> + break;
> case PSCI_0_2_FN_CPU_OFF:
> kvm_psci_vcpu_off(vcpu);
> val = PSCI_RET_SUCCESS;
> @@ -221,10 +245,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
> val = PSCI_RET_INTERNAL_FAILURE;
> ret = 0;
> break;
> - case PSCI_0_2_FN_CPU_SUSPEND:
> - case PSCI_0_2_FN64_CPU_SUSPEND:
> - val = PSCI_RET_NOT_SUPPORTED;
> - break;
> default:
> return -EINVAL;
> }
> --
> 1.7.9.5
>
Acked-by: Christoffer Dall <[email protected]>
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