[RFC 7/9] KVM: KVM-VFIO: add new VFIO external API hooks

[Eric Auger]

add functions that implement the gateway to the extended
external VFIO API:
- kvm_vfio_device_get_external_user
- kvm_vfio_device_put_external_user
- kvm_vfio_external_get_type
- kvm_vfio_external_get_base_device

Signed-off-by: Eric Auger <eric.auger at linaro.org>
---
 arch/arm/include/asm/kvm_host.h |  6 ++++
 virt/kvm/vfio.c                 | 62 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 6dfb404..62cbf5b 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -171,6 +171,12 @@ void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
 int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
 
+struct vfio_device;
+struct vfio_device *kvm_vfio_device_get_external_user(struct file *filep);
+void kvm_vfio_device_put_external_user(struct vfio_device *vdev);
+int kvm_vfio_external_get_type(struct vfio_device *vdev);
+struct device *kvm_vfio_external_get_base_device(struct vfio_device *vdev);
+
 /* We do not have shadow page tables, hence the empty hooks */
 static inline int kvm_age_hva(struct kvm *kvm, unsigned long hva)
 {
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 89d3b75..f1c4e35 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -59,6 +59,67 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
 	symbol_put(vfio_group_put_external_user);
 }
 
+struct vfio_device *kvm_vfio_device_get_external_user(struct file *filep)
+{
+	struct vfio_device *vdev;
+	struct vfio_device *(*fn)(struct file *);
+
+	fn = symbol_get(vfio_device_get_external_user);
+	if (!fn)
+		return ERR_PTR(-EINVAL);
+
+	vdev = fn(filep);
+
+	symbol_put(vfio_device_get_external_user);
+
+	return vdev;
+}
+
+void kvm_vfio_device_put_external_user(struct vfio_device *vdev)
+{
+	void (*fn)(struct vfio_device *);
+
+	fn = symbol_get(vfio_device_put_external_user);
+	if (!fn)
+		return;
+
+	fn(vdev);
+
+	symbol_put(vfio_device_put_external_user);
+}
+
+int kvm_vfio_external_get_type(struct vfio_device *vdev)
+{
+	int (*fn)(struct vfio_device *);
+	int ret;
+
+	fn = symbol_get(vfio_external_get_type);
+	if (!fn)
+		return -EINVAL;
+
+	ret = fn(vdev);
+
+	symbol_put(vfio_external_get_type);
+
+	return ret;
+}
+
+struct device *kvm_vfio_external_get_base_device(struct vfio_device *vdev)
+{
+	struct device *(*fn)(struct vfio_device *);
+	struct device *dev;
+
+	fn = symbol_get(vfio_external_get_base_device);
+	if (!fn)
+		return NULL;
+
+	dev = fn(vdev);
+
+	symbol_put(vfio_external_get_base_device);
+
+	return dev;
+}
+
 static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
 {
 	long (*fn)(struct vfio_group *, unsigned long);
@@ -277,6 +338,7 @@ static int kvm_vfio_create(struct kvm_device *dev, u32 type)
 	return 0;
 }
 
+
 struct kvm_device_ops kvm_vfio_ops = {
 	.name = "kvm-vfio",
 	.create = kvm_vfio_create,
-- 
1.9.1