KVM: Fix unlikely kvm_create vs decache_vcpus_on_cpu race

We add the kvm to the vm_list before initializing the vcpu mutexes,
which can be mutex_trylock()'ed by decache_vcpus_on_cpu().

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index a0a3fddba815..46efbe70801c 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -297,9 +297,6 @@ static struct kvm *kvm_create_vm(void)
         kvm_io_bus_init(&kvm->pio_bus);
         spin_lock_init(&kvm->lock);
         INIT_LIST_HEAD(&kvm->active_mmu_pages);
-        spin_lock(&kvm_lock);
-        list_add(&kvm->vm_list, &vm_list);
-        spin_unlock(&kvm_lock);
         kvm_io_bus_init(&kvm->mmio_bus);
         for (i = 0; i < KVM_MAX_VCPUS; ++i) {
                 struct kvm_vcpu *vcpu = &kvm->vcpus[i];
@@ -309,6 +306,9 @@ static struct kvm *kvm_create_vm(void)
                 vcpu->kvm = kvm;
                 vcpu->mmu.root_hpa = INVALID_PAGE;
         }
+        spin_lock(&kvm_lock);
+        list_add(&kvm->vm_list, &vm_list);
+        spin_unlock(&kvm_lock);
         return kvm;
 }