On Wed, Apr 02, 2014 at 04:12:26PM +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/)
Even if we had stable DT-bindings for PSCI and CPUIDLE driver that uses PSCI CPU_SUSPEND then still we need to define SUSPEND states and WAKEUP events for KVM ARM/ARM64.
Due to above, 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 also consistent with section 5.4.1 and section 5.4.2 of PSCI v0.2 specification.
Signed-off-by: Anup Patel anup.patel@linaro.org Signed-off-by: Pranavkumar Sawargaonkar pranavkumar@linaro.org
arch/arm/kvm/psci.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c index fdbd829..74fa4ad 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/psci.c @@ -52,6 +52,25 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) return affinity_mask; } +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) +{
- /*
* NOTE: Currently, we don't have any wakeup events for KVM* so for simplicity we make VCPU suspend emulation to be* same-as WFI (Wait-for-interrupt) emulation. This is also* consistent with intended use of StateID as described in* section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
The WFI implementation wakes up on interrupts, so we are inherently defining that as a wakeup event for KVM with this patch, so the comment should be adjusted accordingly.
-Christoffer
** 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 PSCI emulation 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; @@ -195,6 +214,10 @@ 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;@@ -232,10 +255,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) val = PSCI_RET_SUCCESS; ret = 0; break;
- case PSCI_0_2_FN_CPU_SUSPEND:
- case PSCI_0_2_FN64_CPU_SUSPEND:
val = PSCI_RET_NOT_SUPPORTED;break;-- 1.7.9.5