ARM DEN0022D.b 5.19 "SYSTEM_SUSPEND" describes a PSCI call that allows
software to request that a system be placed in the deepest possible
low-power state. Effectively, software can use this to suspend itself to
RAM. Note that the semantics of this PSCI call are very similar to
CPU_SUSPEND, which is already implemented in KVM.
Implement the SYSTEM_SUSPEND in KVM. Similar to CPU_SUSPEND, the
low-power state is implemented as a guest WFI. Synchronously reset the
calling CPU before entering the WFI, such that the vCPU may immediately
resume execution when a wakeup event is recognized.
Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
---
arch/arm64/kvm/psci.c | 51 ++++++++++++++++++++++++++++++++++++++++++
arch/arm64/kvm/reset.c | 3 ++-
2 files changed, 53 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index 77a00913cdfd..41adaaf2234a 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -208,6 +208,50 @@ static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
}
+static int kvm_psci_system_suspend(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_reset_state reset_state;
+ struct kvm *kvm = vcpu->kvm;
+ struct kvm_vcpu *tmp;
+ bool denied = false;
+ unsigned long i;
+
+ reset_state.pc = smccc_get_arg1(vcpu);
+ if (!kvm_ipa_valid(kvm, reset_state.pc)) {
+ smccc_set_retval(vcpu, PSCI_RET_INVALID_ADDRESS, 0, 0, 0);
+ return 1;
+ }
+
+ reset_state.r0 = smccc_get_arg2(vcpu);
+ reset_state.be = kvm_vcpu_is_be(vcpu);
+ reset_state.reset = true;
+
+ /*
+ * The SYSTEM_SUSPEND PSCI call requires that all vCPUs (except the
+ * calling vCPU) be in an OFF state, as determined by the
+ * implementation.
+ *
+ * See ARM DEN0022D, 5.19 "SYSTEM_SUSPEND" for more details.
+ */
+ mutex_lock(&kvm->lock);
+ kvm_for_each_vcpu(i, tmp, kvm) {
+ if (tmp != vcpu && !kvm_arm_vcpu_powered_off(tmp)) {
+ denied = true;
+ break;
+ }
+ }
+ mutex_unlock(&kvm->lock);
+
+ if (denied) {
+ smccc_set_retval(vcpu, PSCI_RET_DENIED, 0, 0, 0);
+ return 1;
+ }
+
+ __kvm_reset_vcpu(vcpu, &reset_state);
+ kvm_vcpu_wfi(vcpu);
+ return 1;
+}
+
static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
{
int i;
@@ -343,6 +387,8 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
case PSCI_0_2_FN_SYSTEM_OFF:
case PSCI_0_2_FN_SYSTEM_RESET:
+ case PSCI_1_0_FN_SYSTEM_SUSPEND:
+ case PSCI_1_0_FN64_SYSTEM_SUSPEND:
case PSCI_1_0_FN_PSCI_FEATURES:
case ARM_SMCCC_VERSION_FUNC_ID:
val = 0;
@@ -352,6 +398,11 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
break;
}
break;
+ case PSCI_1_0_FN_SYSTEM_SUSPEND:
+ kvm_psci_narrow_to_32bit(vcpu);
+ fallthrough;
+ case PSCI_1_0_FN64_SYSTEM_SUSPEND:
+ return kvm_psci_system_suspend(vcpu);
default:
return kvm_psci_0_2_call(vcpu);
}
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index f879a8f6a99c..006e7a75ceba 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -215,7 +215,8 @@ static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
*
* Note: This function can be called from two paths:
* - The KVM_ARM_VCPU_INIT ioctl
- * - handling a request issued by another VCPU in the PSCI handling code
+ * - handling a request issued by possibly another VCPU in the PSCI handling
+ * code
*
* In the first case, the VCPU will not be loaded, and in the second case the
* VCPU will be loaded. Because this function operates purely on the
--
2.35.1.473.g83b2b277ed-goog
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