arm/arm64: KVM: vgic: Fix error code in kvm_vgic_create()

If we detect another vCPU is running we just exit and return 0 as if we
succesfully created the VGIC, but the VGIC wouldn't actual be created.

This shouldn't break in-kernel behavior because the kernel will not
observe the failed the attempt to create the VGIC, but userspace could
be rightfully confused.

Cc: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 3aaca49de3257eed0bd905ac26112cacd49588dd..aacdb59f30dedcd780ee29e2903d928194a42a5c 100644 (file)
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1933,7 +1933,7 @@ out:
 
 int kvm_vgic_create(struct kvm *kvm)
 {
-       int i, vcpu_lock_idx = -1, ret = 0;
+       int i, vcpu_lock_idx = -1, ret;
        struct kvm_vcpu *vcpu;
 
        mutex_lock(&kvm->lock);
@@ -1948,6 +1948,7 @@ int kvm_vgic_create(struct kvm *kvm)
         * vcpu->mutex.  By grabbing the vcpu->mutex of all VCPUs we ensure
         * that no other VCPUs are run while we create the vgic.
         */
+       ret = -EBUSY;
        kvm_for_each_vcpu(i, vcpu, kvm) {
                if (!mutex_trylock(&vcpu->mutex))
                        goto out_unlock;
@@ -1955,11 +1956,10 @@ int kvm_vgic_create(struct kvm *kvm)
        }
 
        kvm_for_each_vcpu(i, vcpu, kvm) {
-               if (vcpu->arch.has_run_once) {
-                       ret = -EBUSY;
+               if (vcpu->arch.has_run_once)
                        goto out_unlock;
-               }
        }
+       ret = 0;
 
        spin_lock_init(&kvm->arch.vgic.lock);
        kvm->arch.vgic.in_kernel = true;