KVM: Convert vm lock to a mutex

This allows the kvm mmu to perform sleepy operations, such as memory
allocation.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 0667183..1072c83 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -393,7 +393,7 @@
 };
 
 struct kvm {
-	spinlock_t lock; /* protects everything except vcpus */
+	struct mutex lock; /* protects everything except vcpus */
 	int naliases;
 	struct kvm_mem_alias aliases[KVM_ALIAS_SLOTS];
 	int nmemslots;