KVM: device: add simple registration mechanism for kvm_device_ops

kvm_ioctl_create_device currently has knowledge of all the device types
and their associated ops. This is fairly inflexible when adding support
for new in-kernel device emulations, so move what we currently have out
into a table, which can support dynamic registration of ops by new
drivers for virtual hardware.

Cc: Alex Williamson <Alex.Williamson@redhat.com>
Cc: Alex Graf <agraf@suse.de>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit d60eacb07053142bfb9b41582074a89a790a9d46)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ce4cf2f1c419337fe2aa4a1a045a6ebdace1e963..fc7b4270bc4a2bc57ad5c882167fdfdede1baef3 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1022,6 +1022,7 @@ 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);
 
 extern struct kvm_device_ops kvm_mpic_ops;
 extern struct kvm_device_ops kvm_xics_ops;

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index bbc1f8a09eb82ca690fe73c0387cfce57577fb67..00d2c69a3cb67a0e8424163aaf1655c0ba5d1f5a 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -848,14 +848,25 @@ struct kvm_device_attr {
        __u64   addr;           /* userspace address of attr data */
 };
 
-#define KVM_DEV_TYPE_FSL_MPIC_20       1
-#define KVM_DEV_TYPE_FSL_MPIC_42       2
-#define KVM_DEV_TYPE_XICS              3
-#define KVM_DEV_TYPE_VFIO              4
 #define  KVM_DEV_VFIO_GROUP                    1
 #define   KVM_DEV_VFIO_GROUP_ADD                       1
 #define   KVM_DEV_VFIO_GROUP_DEL                       2
-#define KVM_DEV_TYPE_ARM_VGIC_V2       5
+
+enum kvm_device_type {
+       KVM_DEV_TYPE_FSL_MPIC_20        = 1,
+#define KVM_DEV_TYPE_FSL_MPIC_20       KVM_DEV_TYPE_FSL_MPIC_20
+       KVM_DEV_TYPE_FSL_MPIC_42,
+#define KVM_DEV_TYPE_FSL_MPIC_42       KVM_DEV_TYPE_FSL_MPIC_42
+       KVM_DEV_TYPE_XICS,
+#define KVM_DEV_TYPE_XICS              KVM_DEV_TYPE_XICS
+       KVM_DEV_TYPE_VFIO,
+#define KVM_DEV_TYPE_VFIO              KVM_DEV_TYPE_VFIO
+       KVM_DEV_TYPE_ARM_VGIC_V2,
+#define KVM_DEV_TYPE_ARM_VGIC_V2       KVM_DEV_TYPE_ARM_VGIC_V2
+       KVM_DEV_TYPE_FLIC,
+#define KVM_DEV_TYPE_FLIC              KVM_DEV_TYPE_FLIC
+       KVM_DEV_TYPE_MAX,
+};
 
 /*
  * ioctls for VM fds

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3ed27192a849a49d55c84bb14fb853a4d888aa9b..df006d12c14bda4f70eba767bd12ca8400487128 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2261,39 +2261,51 @@ struct kvm_device *kvm_device_from_filp(struct file *filp)
        return filp->private_data;
 }
 
-static int kvm_ioctl_create_device(struct kvm *kvm,
-                                  struct kvm_create_device *cd)
-{
-       struct kvm_device_ops *ops = NULL;
-       struct kvm_device *dev;
-       bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
-       int ret;
-
-       switch (cd->type) {
+static struct kvm_device_ops *kvm_device_ops_table[KVM_DEV_TYPE_MAX] = {
 #ifdef CONFIG_KVM_MPIC
-       case KVM_DEV_TYPE_FSL_MPIC_20:
-       case KVM_DEV_TYPE_FSL_MPIC_42:
-               ops = &kvm_mpic_ops;
-               break;
+       [KVM_DEV_TYPE_FSL_MPIC_20]      = &kvm_mpic_ops,
+       [KVM_DEV_TYPE_FSL_MPIC_42]      = &kvm_mpic_ops,
 #endif
+
 #ifdef CONFIG_KVM_XICS
-       case KVM_DEV_TYPE_XICS:
-               ops = &kvm_xics_ops;
-               break;
+       [KVM_DEV_TYPE_XICS]             = &kvm_xics_ops,
 #endif
+
 #ifdef CONFIG_KVM_VFIO
-       case KVM_DEV_TYPE_VFIO:
-               ops = &kvm_vfio_ops;
-               break;
+       [KVM_DEV_TYPE_VFIO]             = &kvm_vfio_ops,
 #endif
+
 #ifdef CONFIG_KVM_ARM_VGIC
-       case KVM_DEV_TYPE_ARM_VGIC_V2:
-               ops = &kvm_arm_vgic_v2_ops;
-               break;
+       [KVM_DEV_TYPE_ARM_VGIC_V2]      = &kvm_arm_vgic_v2_ops,
 #endif
-       default:
+};
+
+int kvm_register_device_ops(struct kvm_device_ops *ops, u32 type)
+{
+       if (type >= ARRAY_SIZE(kvm_device_ops_table))
+               return -ENOSPC;
+
+       if (kvm_device_ops_table[type] != NULL)
+               return -EEXIST;
+
+       kvm_device_ops_table[type] = ops;
+       return 0;
+}
+
+static int kvm_ioctl_create_device(struct kvm *kvm,
+                                  struct kvm_create_device *cd)
+{
+       struct kvm_device_ops *ops = NULL;
+       struct kvm_device *dev;
+       bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
+       int ret;
+
+       if (cd->type >= ARRAY_SIZE(kvm_device_ops_table))
+               return -ENODEV;
+
+       ops = kvm_device_ops_table[cd->type];
+       if (ops == NULL)
                return -ENODEV;
-       }
 
        if (test)
                return 0;