[PATCH 3.14 27/34] arm/arm64: KVM: vgic: Fix error code in kvm_vgic_create()

Greg Kroah-Hartman
2015-07-01T18:44:05Z

From: Christoffer Dall <christoffer.dall@linaro.org>

commit 6b50f54064a02b77a7b990032b80234fee59bcd6 upstream.

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>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
virt/kvm/arm/vgic.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1611,7 +1611,7 @@ 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);
@@ -1626,6 +1626,7 @@ 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;
@@ -1633,11 +1634,10 @@ 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.vctrl_base = vgic_vctrl_base;