[PATCH v2] KVM: mark memory slots as rcu

[Christian Borntraeger <borntraeger@de.ibm.com>]

we access the memslots array via srcu. Mark it as such and
use the right access functions also for the freeing of
memory slots.

Found by sparse:
./include/linux/kvm_host.h:565:16: error: incompatible types in
comparison expression (different address spaces)

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
v1->v2: use rcu_dereference_protected instead of rcu_access_pointer
 include/linux/kvm_host.h | 2 +-
 virt/kvm/kvm_main.c      | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bcd37b8..7c32905 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -390,7 +390,7 @@ struct kvm {
 	spinlock_t mmu_lock;
 	struct mutex slots_lock;
 	struct mm_struct *mm; /* userspace tied to this vm */
-	struct kvm_memslots *memslots[KVM_ADDRESS_SPACE_NUM];
+	struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM];
 	struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
 
 	/*
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fc2d583..e3e6fec 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -707,7 +707,8 @@ static struct kvm *kvm_create_vm(unsigned long type)
 	for (i = 0; i < KVM_NR_BUSES; i++)
 		kfree(kvm->buses[i]);
 	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
-		kvm_free_memslots(kvm, kvm->memslots[i]);
+		kvm_free_memslots(kvm,
+			rcu_dereference_protected(kvm->memslots[i], 1));
 	kvm_arch_free_vm(kvm);
 	mmdrop(current->mm);
 	return ERR_PTR(r);
@@ -753,7 +754,8 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	kvm_arch_destroy_vm(kvm);
 	kvm_destroy_devices(kvm);
 	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
-		kvm_free_memslots(kvm, kvm->memslots[i]);
+		kvm_free_memslots(kvm,
+			rcu_dereference_protected(kvm->memslots[i], 1));
 	cleanup_srcu_struct(&kvm->irq_srcu);
 	cleanup_srcu_struct(&kvm->srcu);
 	kvm_arch_free_vm(kvm);
-- 
2.7.4