KVM: Allow kvm_device_ops to be const

Currently a kvm_device_ops structure cannot be const without triggering
compiler warnings. However the structure doesn't need to be written to
and, by marking it const, it can be read-only in memory. Add some more
const keywords to allow this.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9907e45..7a26d55 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1262,7 +1262,7 @@ extern unsigned int halt_poll_ns_grow_start;
 extern unsigned int halt_poll_ns_shrink;
 
 struct kvm_device {
-       struct kvm_device_ops *ops;
+       const struct kvm_device_ops *ops;
        struct kvm *kvm;
        void *private;
        struct list_head vm_node;
@@ -1315,7 +1315,7 @@ struct kvm_device_ops {
 void kvm_device_get(struct kvm_device *dev);
 void kvm_device_put(struct kvm_device *dev);
 struct kvm_device *kvm_device_from_filp(struct file *filp);
-int kvm_register_device_ops(struct kvm_device_ops *ops, u32 type);
+int kvm_register_device_ops(const struct kvm_device_ops *ops, u32 type);
 void kvm_unregister_device_ops(u32 type);
 
 extern struct kvm_device_ops kvm_mpic_ops;

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fd68fbe..66a9774 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3046,14 +3046,14 @@ struct kvm_device *kvm_device_from_filp(struct file *filp)
        return filp->private_data;
 }
 
-static struct kvm_device_ops *kvm_device_ops_table[KVM_DEV_TYPE_MAX] = {
+static const struct kvm_device_ops *kvm_device_ops_table[KVM_DEV_TYPE_MAX] = {
 #ifdef CONFIG_KVM_MPIC
        [KVM_DEV_TYPE_FSL_MPIC_20]      = &kvm_mpic_ops,
        [KVM_DEV_TYPE_FSL_MPIC_42]      = &kvm_mpic_ops,
 #endif
 };
 
-int kvm_register_device_ops(struct kvm_device_ops *ops, u32 type)
+int kvm_register_device_ops(const struct kvm_device_ops *ops, u32 type)
 {
        if (type >= ARRAY_SIZE(kvm_device_ops_table))
                return -ENOSPC;
@@ -3074,7 +3074,7 @@ void kvm_unregister_device_ops(u32 type)
 static int kvm_ioctl_create_device(struct kvm *kvm,
                                   struct kvm_create_device *cd)
 {
-       struct kvm_device_ops *ops = NULL;
+       const struct kvm_device_ops *ops = NULL;
        struct kvm_device *dev;
        bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
        int type;