[PATCH v4 06/10] KVM: Allow kvm_device_ops to be const

From: Steven Price <steven.price@arm.com>
To: Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Cc: "Steven Price" <steven.price@arm.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Russell King" <linux@armlinux.org.uk>,
	"James Morse" <james.morse@arm.com>,
	"Julien Thierry" <julien.thierry.kdev@gmail.com>,
	"Suzuki K Pouloze" <suzuki.poulose@arm.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	kvm@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 06/10] KVM: Allow kvm_device_ops to be const
Date: Fri, 30 Aug 2019 09:42:51 +0100	[thread overview]
Message-ID: <20190830084255.55113-7-steven.price@arm.com> (raw)
In-Reply-To: <20190830084255.55113-1-steven.price@arm.com>

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.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 include/linux/kvm_host.h | 4 ++--
 virt/kvm/kvm_main.c      | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bf0ae1825b9c..4e65f7566913 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1260,7 +1260,7 @@ 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;
@@ -1313,7 +1313,7 @@ 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 c6a91b044d8d..75488ebb87c9 100644
--- 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;
-- 
2.20.1

