arm/arm64: KVM: Correct KVM_ARM_VCPU_INIT power off option

The implementation of KVM_ARM_VCPU_INIT is currently not doing what
userspace expects, namely making sure that a vcpu which may have been
turned off using PSCI is returned to its initial state, which would be
powered on if userspace does not set the KVM_ARM_VCPU_POWER_OFF flag.

Implement the expected functionality and clarify the ABI.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

2 files changed, 4 insertions, 1 deletions

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 7610eaa4d491..bb82a906e51e 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2455,7 +2455,8 @@ should be created before this ioctl is invoked.
 
 Possible features:
         - KVM_ARM_VCPU_POWER_OFF: Starts the CPU in a power-off state.
-          Depends on KVM_CAP_ARM_PSCI.
+          Depends on KVM_CAP_ARM_PSCI.  If not set, the CPU will be powered on
+          and execute guest code when KVM_RUN is called.
         - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
           Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
         - KVM_ARM_VCPU_PSCI_0_2: Emulate PSCI v0.2 for the CPU.
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index b160beadc956..edc196412abe 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -663,6 +663,8 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
          */
         if (test_bit(KVM_ARM_VCPU_POWER_OFF, vcpu->arch.features))
                 vcpu->arch.pause = true;
+        else
+                vcpu->arch.pause = false;
 
         return 0;
 }