On Fri, Mar 21, 2014 at 06:23:33PM +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 for KVM we simply 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 for KVM ARM/ARM64.
Due to this, the CPU_SUSPEND emulation added by this patch only pause current VCPU and to wakeup a suspended VCPU we need to explicity call PSCI CPU_ON from Guest.
Signed-off-by: Anup Patel anup.patel@linaro.org Signed-off-by: Pranavkumar Sawargaonkar pranavkumar@linaro.org
arch/arm/kvm/psci.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c index 1e85452..e32ad10 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/psci.c @@ -52,6 +52,22 @@ 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* hence VCPU suspend turns-out to be same as VCPU off request.* This means to suspend a VCPU we simply set the pause flag* and update VCPU registers as-per wakeup parameters provided* via r2 & r3 (or x2 & x3).*/- vcpu->arch.pause = true;
- *vcpu_pc(vcpu) = *vcpu_reg(vcpu, 2);
- *vcpu_reg(vcpu, 0) = *vcpu_reg(vcpu, 3);
But the spec states in Section 5.1.2 that if Bit[16] StateType == 0, then the entry point and context_id parameters are ignored, because all state is retained for a standby state.
I think Mark Rutland commented that KVM should define at last interrupts to the CPU as a wakeup event.
- return KVM_PSCI_RET_SUCCESS;
+}
static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu) { vcpu->arch.pause = true; @@ -195,6 +211,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) */ val = 2; break;
- case KVM_PSCI_0_2_FN_CPU_SUSPEND:
- case KVM_PSCI_0_2_FN64_CPU_SUSPEND:
val = kvm_psci_vcpu_suspend(vcpu);break;@@ -232,10 +252,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) val = KVM_PSCI_RET_SUCCESS; ret = 0; break;
- case KVM_PSCI_0_2_FN_CPU_SUSPEND:
- case KVM_PSCI_0_2_FN64_CPU_SUSPEND:
val = KVM_PSCI_RET_NI;break;-- 1.7.9.5
Thanks, -Christoffer