arm/arm64: kvm: Set vcpu->cpu to -1 on vcpu_put

commit e9b152cb upstream.

The arch-generic KVM code expects the cpu field of a vcpu to be -1 if
the vcpu is no longer assigned to a cpu.  This is used for the optimized
make_all_cpus_request path and will be used by the vgic code to check
that no vcpus are running.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

arch/arm/kvm/arm.c

@@ -340,6 +340,13 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
+	/*
+	 * The arch-generic KVM code expects the cpu field of a vcpu to be -1
+	 * if the vcpu is no longer assigned to a cpu.  This is used for the
+	 * optimized make_all_cpus_request path.
+	 */
+	vcpu->cpu = -1;
+
 	kvm_arm_set_running_vcpu(NULL);
 }