From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Thu, 6 Jul 2017 16:17:14 +0200
Subject: KVM: mark memory slots as rcu
Patch-mainline: v4.13-rc1
Git-commit: a80cf7b5f4149753d5f19c872a47e66195b167d4
References: bsc#1077761

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>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Alexander Graf <agraf@suse.de>
---
 include/linux/kvm_host.h |    2 +-
 virt/kvm/kvm_main.c      |    6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -390,7 +390,7 @@
 	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];
 
 	/*
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -713,7 +713,8 @@
 	for (i = 0; i < KVM_NR_BUSES; i++)
 		kfree(rcu_access_pointer(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);
@@ -762,7 +763,8 @@
 	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);