diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 4682207b1ac8..813a2e67aa0c 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -175,7 +175,7 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
 static void vfio_pci_disable(struct vfio_pci_device *vdev)
 {
 	struct pci_dev *pdev = vdev->pdev;
-	int bar;
+	int i, bar;
 
 	/* Stop the device from further DMA */
 	pci_clear_master(pdev);
@@ -186,6 +186,13 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
 
 	vdev->virq_disabled = false;
 
+	for (i = 0; i < vdev->num_regions; i++)
+		vdev->region[i].ops->release(vdev, &vdev->region[i]);
+
+	vdev->num_regions = 0;
+	kfree(vdev->region);
+	vdev->region = NULL; /* don't krealloc a freed pointer */
+
 	vfio_config_free(vdev);
 
 	for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) {
@@ -463,6 +470,51 @@ static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
 	return 0;
 }
 
+static int region_type_cap(struct vfio_pci_device *vdev,
+			   struct vfio_info_cap *caps,
+			   unsigned int type, unsigned int subtype)
+{
+	struct vfio_info_cap_header *header;
+	struct vfio_region_info_cap_type *cap;
+
+	header = vfio_info_cap_add(caps, sizeof(*cap),
+				   VFIO_REGION_INFO_CAP_TYPE, 1);
+	if (IS_ERR(header))
+		return PTR_ERR(header);
+
+	cap = container_of(header, struct vfio_region_info_cap_type, header);
+	cap->type = type;
+	cap->subtype = subtype;
+
+	return 0;
+}
+
+int vfio_pci_register_dev_region(struct vfio_pci_device *vdev,
+				 unsigned int type, unsigned int subtype,
+				 const struct vfio_pci_regops *ops,
+				 size_t size, u32 flags, void *data)
+{
+	struct vfio_pci_region *region;
+
+	region = krealloc(vdev->region,
+			  (vdev->num_regions + 1) * sizeof(*region),
+			  GFP_KERNEL);
+	if (!region)
+		return -ENOMEM;
+
+	vdev->region = region;
+	vdev->region[vdev->num_regions].type = type;
+	vdev->region[vdev->num_regions].subtype = subtype;
+	vdev->region[vdev->num_regions].ops = ops;
+	vdev->region[vdev->num_regions].size = size;
+	vdev->region[vdev->num_regions].flags = flags;
+	vdev->region[vdev->num_regions].data = data;
+
+	vdev->num_regions++;
+
+	return 0;
+}
+
 static long vfio_pci_ioctl(void *device_data,
 			   unsigned int cmd, unsigned long arg)
 {
@@ -485,7 +537,7 @@ static long vfio_pci_ioctl(void *device_data,
 		if (vdev->reset_works)
 			info.flags |= VFIO_DEVICE_FLAGS_RESET;
 
-		info.num_regions = VFIO_PCI_NUM_REGIONS;
+		info.num_regions = VFIO_PCI_NUM_REGIONS + vdev->num_regions;
 		info.num_irqs = VFIO_PCI_NUM_IRQS;
 
 		return copy_to_user((void __user *)arg, &info, minsz);
@@ -494,7 +546,7 @@ static long vfio_pci_ioctl(void *device_data,
 		struct pci_dev *pdev = vdev->pdev;
 		struct vfio_region_info info;
 		struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
-		int ret;
+		int i, ret;
 
 		minsz = offsetofend(struct vfio_region_info, offset);
 
@@ -568,7 +620,21 @@ static long vfio_pci_ioctl(void *device_data,
 
 			break;
 		default:
-			return -EINVAL;
+			if (info.index >=
+			    VFIO_PCI_NUM_REGIONS + vdev->num_regions)
+				return -EINVAL;
+
+			i = info.index - VFIO_PCI_NUM_REGIONS;
+
+			info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
+			info.size = vdev->region[i].size;
+			info.flags = vdev->region[i].flags;
+
+			ret = region_type_cap(vdev, &caps,
+					      vdev->region[i].type,
+					      vdev->region[i].subtype);
+			if (ret)
+				return ret;
 		}
 
 		if (caps.size) {
@@ -866,7 +932,7 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
 	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
 	struct vfio_pci_device *vdev = device_data;
 
-	if (index >= VFIO_PCI_NUM_REGIONS)
+	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
 		return -EINVAL;
 
 	switch (index) {
@@ -883,6 +949,10 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
 
 	case VFIO_PCI_VGA_REGION_INDEX:
 		return vfio_pci_vga_rw(vdev, buf, count, ppos, iswrite);
+	default:
+		index -= VFIO_PCI_NUM_REGIONS;
+		return vdev->region[index].ops->rw(vdev, buf,
+						   count, ppos, iswrite);
 	}
 
 	return -EINVAL;
@@ -1065,6 +1135,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)
 		return;
 
 	vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
+	kfree(vdev->region);
 	kfree(vdev);
 
 	if (vfio_pci_is_vga(pdev)) {
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 0e7394f8f69b..0710bda5ae2c 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -14,6 +14,7 @@
 #include <linux/mutex.h>
 #include <linux/pci.h>
 #include <linux/irqbypass.h>
+#include <linux/types.h>
 
 #ifndef VFIO_PCI_PRIVATE_H
 #define VFIO_PCI_PRIVATE_H
@@ -33,6 +34,25 @@ struct vfio_pci_irq_ctx {
 	struct irq_bypass_producer	producer;
 };
 
+struct vfio_pci_device;
+struct vfio_pci_region;
+
+struct vfio_pci_regops {
+	size_t	(*rw)(struct vfio_pci_device *vdev, char __user *buf,
+		      size_t count, loff_t *ppos, bool iswrite);
+	void	(*release)(struct vfio_pci_device *vdev,
+			   struct vfio_pci_region *region);
+};
+
+struct vfio_pci_region {
+	u32				type;
+	u32				subtype;
+	const struct vfio_pci_regops	*ops;
+	void				*data;
+	size_t				size;
+	u32				flags;
+};
+
 struct vfio_pci_device {
 	struct pci_dev		*pdev;
 	void __iomem		*barmap[PCI_STD_RESOURCE_END + 1];
@@ -45,6 +65,8 @@ struct vfio_pci_device {
 	struct vfio_pci_irq_ctx	*ctx;
 	int			num_ctx;
 	int			irq_type;
+	int			num_regions;
+	struct vfio_pci_region	*region;
 	u8			msi_qmax;
 	u8			msix_bar;
 	u16			msix_size;
@@ -91,4 +113,9 @@ extern void vfio_pci_uninit_perm_bits(void);
 
 extern int vfio_config_init(struct vfio_pci_device *vdev);
 extern void vfio_config_free(struct vfio_pci_device *vdev);
+
+extern int vfio_pci_register_dev_region(struct vfio_pci_device *vdev,
+					unsigned int type, unsigned int subtype,
+					const struct vfio_pci_regops *ops,
+					size_t size, u32 flags, void *data);
 #endif /* VFIO_PCI_PRIVATE_H */