From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 23 Jul 2007 07:08:21 +0000 (+1000)
Subject: KVM: Fix unlikely kvm_create vs decache_vcpus_on_cpu race
X-Git-Tag: kvm-32~2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e8c2eb98b58dd135b14d87e6dd1d621bc630d919;p=users%2Fdwmw2%2Flinux.git

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>
---

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index e7c9ca75eb0a2..84037d62c2b96 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -302,9 +302,6 @@ 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];
@@ -314,6 +311,9 @@ 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;
 }