KVM: arm/arm64: Hold slots_lock when unregistering kvm io bus devices

We were not holding the kvm->slots_lock as required when calling
kvm_io_bus_unregister_dev() as required.

This only affects the error path, but still, let's do our due
diligence.

Reported by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
index 9b0f6810e7a8..201d5e2e973d 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
@@ -614,15 +614,16 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu)
         mutex_lock(&kvm->slots_lock);
         ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, sgi_base,
                                       SZ_64K, &sgi_dev->dev);
-        mutex_unlock(&kvm->slots_lock);
         if (ret) {
                 kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
                                           &rd_dev->dev);
-                return ret;
+                goto out;
         }
 
         vgic->vgic_redist_free_offset += 2 * SZ_64K;
-        return 0;
+out:
+        mutex_unlock(&kvm->slots_lock);
+        return ret;
 }
 
 static void vgic_unregister_redist_iodev(struct kvm_vcpu *vcpu)
@@ -647,10 +648,12 @@ static int vgic_register_all_redist_iodevs(struct kvm *kvm)
 
         if (ret) {
                 /* The current c failed, so we start with the previous one. */
+                mutex_lock(&kvm->slots_lock);
                 for (c--; c >= 0; c--) {
                         vcpu = kvm_get_vcpu(kvm, c);
                         vgic_unregister_redist_iodev(vcpu);
                 }
+                mutex_unlock(&kvm->slots_lock);
         }
 
         return ret;