diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 188b1ff03f5f..f312cbb0eebc 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -478,12 +478,12 @@ static int vfio_pci_for_each_slot_or_bus(struct pci_dev *pdev,
 }
 
 static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
+				struct vfio_region_info *info,
 				struct vfio_info_cap *caps)
 {
-	struct vfio_info_cap_header *header;
 	struct vfio_region_info_cap_sparse_mmap *sparse;
 	size_t end, size;
-	int nr_areas = 2, i = 0;
+	int nr_areas = 2, i = 0, ret;
 
 	end = pci_resource_len(vdev->pdev, vdev->msix_bar);
 
@@ -494,13 +494,10 @@ static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
 
 	size = sizeof(*sparse) + (nr_areas * sizeof(*sparse->areas));
 
-	header = vfio_info_cap_add(caps, size,
-				   VFIO_REGION_INFO_CAP_SPARSE_MMAP, 1);
-	if (IS_ERR(header))
-		return PTR_ERR(header);
+	sparse = kzalloc(size, GFP_KERNEL);
+	if (!sparse)
+		return -ENOMEM;
 
-	sparse = container_of(header,
-			      struct vfio_region_info_cap_sparse_mmap, header);
 	sparse->nr_areas = nr_areas;
 
 	if (vdev->msix_offset & PAGE_MASK) {
@@ -516,24 +513,14 @@ static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
 		i++;
 	}
 
-	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;
+	info->flags |= VFIO_REGION_INFO_FLAG_CAPS;
 
-	header = vfio_info_cap_add(caps, sizeof(*cap),
-				   VFIO_REGION_INFO_CAP_TYPE, 1);
-	if (IS_ERR(header))
-		return PTR_ERR(header);
+	ret = vfio_info_add_capability(info, caps,
+				      VFIO_REGION_INFO_CAP_SPARSE_MMAP, sparse);
+	kfree(sparse);
 
-	cap = container_of(header, struct vfio_region_info_cap_type, header);
-	cap->type = type;
-	cap->subtype = subtype;
+	if (ret)
+		return ret;
 
 	return 0;
 }
@@ -628,7 +615,8 @@ static long vfio_pci_ioctl(void *device_data,
 			    IORESOURCE_MEM && info.size >= PAGE_SIZE) {
 				info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
 				if (info.index == vdev->msix_bar) {
-					ret = msix_sparse_mmap_cap(vdev, &caps);
+					ret = msix_sparse_mmap_cap(vdev, &info,
+								   &caps);
 					if (ret)
 						return ret;
 				}
@@ -676,6 +664,9 @@ static long vfio_pci_ioctl(void *device_data,
 
 			break;
 		default:
+		{
+			struct vfio_region_info_cap_type cap_type;
+
 			if (info.index >=
 			    VFIO_PCI_NUM_REGIONS + vdev->num_regions)
 				return -EINVAL;
@@ -684,29 +675,26 @@ static long vfio_pci_ioctl(void *device_data,
 
 			info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
 			info.size = vdev->region[i].size;
-			info.flags = vdev->region[i].flags;
+			info.flags = vdev->region[i].flags |
+				     VFIO_REGION_INFO_FLAG_CAPS;
 
-			ret = region_type_cap(vdev, &caps,
-					      vdev->region[i].type,
-					      vdev->region[i].subtype);
+			cap_type.type = vdev->region[i].type;
+			cap_type.subtype = vdev->region[i].subtype;
+
+			ret = vfio_info_add_capability(&info, &caps,
+						      VFIO_REGION_INFO_CAP_TYPE,
+						      &cap_type);
 			if (ret)
 				return ret;
+
+		}
 		}
 
-		if (caps.size) {
-			info.flags |= VFIO_REGION_INFO_FLAG_CAPS;
-			if (info.argsz < sizeof(info) + caps.size) {
-				info.argsz = sizeof(info) + caps.size;
-				info.cap_offset = 0;
-			} else {
-				vfio_info_cap_shift(&caps, sizeof(info));
-				if (copy_to_user((void __user *)arg +
-						  sizeof(info), caps.buf,
-						  caps.size)) {
-					kfree(caps.buf);
-					return -EFAULT;
-				}
-				info.cap_offset = sizeof(info);
+		if (info.cap_offset) {
+			if (copy_to_user((void __user *)arg + info.cap_offset,
+					 caps.buf, caps.size)) {
+				kfree(caps.buf);
+				return -EFAULT;
 			}
 
 			kfree(caps.buf);
@@ -754,35 +742,22 @@ static long vfio_pci_ioctl(void *device_data,
 	} else if (cmd == VFIO_DEVICE_SET_IRQS) {
 		struct vfio_irq_set hdr;
 		u8 *data = NULL;
-		int ret = 0;
+		int max, ret = 0, data_size = 0;
 
 		minsz = offsetofend(struct vfio_irq_set, count);
 
 		if (copy_from_user(&hdr, (void __user *)arg, minsz))
 			return -EFAULT;
 
-		if (hdr.argsz < minsz || hdr.index >= VFIO_PCI_NUM_IRQS ||
-		    hdr.flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
-				  VFIO_IRQ_SET_ACTION_TYPE_MASK))
-			return -EINVAL;
-
-		if (!(hdr.flags & VFIO_IRQ_SET_DATA_NONE)) {
-			size_t size;
-			int max = vfio_pci_get_irq_count(vdev, hdr.index);
+		max = vfio_pci_get_irq_count(vdev, hdr.index);
 
-			if (hdr.flags & VFIO_IRQ_SET_DATA_BOOL)
-				size = sizeof(uint8_t);
-			else if (hdr.flags & VFIO_IRQ_SET_DATA_EVENTFD)
-				size = sizeof(int32_t);
-			else
-				return -EINVAL;
-
-			if (hdr.argsz - minsz < hdr.count * size ||
-			    hdr.start >= max || hdr.start + hdr.count > max)
-				return -EINVAL;
+		ret = vfio_set_irqs_validate_and_prepare(&hdr, max, &data_size);
+		if (ret)
+			return ret;
 
+		if (data_size) {
 			data = memdup_user((void __user *)(arg + minsz),
-					   hdr.count * size);
+					    data_size);
 			if (IS_ERR(data))
 				return PTR_ERR(data);
 		}
@@ -790,7 +765,7 @@ static long vfio_pci_ioctl(void *device_data,
 		mutex_lock(&vdev->igate);
 
 		ret = vfio_pci_set_irqs_ioctl(vdev, hdr.flags, hdr.index,
-					      hdr.start, hdr.count, data);
+				hdr.start, hdr.count, data);
 
 		mutex_unlock(&vdev->igate);
 		kfree(data);
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index e3e342861e04..0185d5fb2c85 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1782,6 +1782,122 @@ void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset)
 }
 EXPORT_SYMBOL_GPL(vfio_info_cap_shift);
 
+static int sparse_mmap_cap(struct vfio_info_cap *caps, void *cap_type)
+{
+	struct vfio_info_cap_header *header;
+	struct vfio_region_info_cap_sparse_mmap *sparse_cap, *sparse = cap_type;
+	size_t size;
+
+	size = sizeof(*sparse) + sparse->nr_areas *  sizeof(*sparse->areas);
+	header = vfio_info_cap_add(caps, size,
+				   VFIO_REGION_INFO_CAP_SPARSE_MMAP, 1);
+	if (IS_ERR(header))
+		return PTR_ERR(header);
+
+	sparse_cap = container_of(header,
+			struct vfio_region_info_cap_sparse_mmap, header);
+	sparse_cap->nr_areas = sparse->nr_areas;
+	memcpy(sparse_cap->areas, sparse->areas,
+	       sparse->nr_areas * sizeof(*sparse->areas));
+	return 0;
+}
+
+static int region_type_cap(struct vfio_info_cap *caps, void *cap_type)
+{
+	struct vfio_info_cap_header *header;
+	struct vfio_region_info_cap_type *type_cap, *cap = cap_type;
+
+	header = vfio_info_cap_add(caps, sizeof(*cap),
+				   VFIO_REGION_INFO_CAP_TYPE, 1);
+	if (IS_ERR(header))
+		return PTR_ERR(header);
+
+	type_cap = container_of(header, struct vfio_region_info_cap_type,
+				header);
+	type_cap->type = cap->type;
+	type_cap->subtype = cap->subtype;
+	return 0;
+}
+
+int vfio_info_add_capability(struct vfio_region_info *info,
+			     struct vfio_info_cap *caps,
+			     int cap_type_id,
+			     void *cap_type)
+{
+	int ret;
+
+	if (!(info->flags & VFIO_REGION_INFO_FLAG_CAPS) || !cap_type)
+		return 0;
+
+	switch (cap_type_id) {
+	case VFIO_REGION_INFO_CAP_SPARSE_MMAP:
+		ret = sparse_mmap_cap(caps, cap_type);
+		if (ret)
+			return ret;
+		break;
+
+	case VFIO_REGION_INFO_CAP_TYPE:
+		ret = region_type_cap(caps, cap_type);
+		if (ret)
+			return ret;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (caps->size) {
+		if (info->argsz < sizeof(*info) + caps->size) {
+			info->argsz = sizeof(*info) + caps->size;
+			info->cap_offset = 0;
+		} else {
+			vfio_info_cap_shift(caps, sizeof(*info));
+			info->cap_offset = sizeof(*info);
+		}
+	}
+	return 0;
+}
+EXPORT_SYMBOL(vfio_info_add_capability);
+
+int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr, int num_irqs,
+				       int *data_size)
+{
+	unsigned long minsz;
+
+	minsz = offsetofend(struct vfio_irq_set, count);
+
+	if ((hdr->argsz < minsz) || (hdr->index >= VFIO_PCI_NUM_IRQS) ||
+	    (hdr->flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
+				VFIO_IRQ_SET_ACTION_TYPE_MASK)))
+		return -EINVAL;
+
+	if (data_size)
+		*data_size = 0;
+
+	if (!(hdr->flags & VFIO_IRQ_SET_DATA_NONE)) {
+		size_t size;
+
+		if (hdr->flags & VFIO_IRQ_SET_DATA_BOOL)
+			size = sizeof(uint8_t);
+		else if (hdr->flags & VFIO_IRQ_SET_DATA_EVENTFD)
+			size = sizeof(int32_t);
+		else
+			return -EINVAL;
+
+		if ((hdr->argsz - minsz < hdr->count * size) ||
+		    (hdr->start >= num_irqs) ||
+		    (hdr->start + hdr->count > num_irqs))
+			return -EINVAL;
+
+		if (!data_size)
+			return -EINVAL;
+
+		*data_size = hdr->count * size;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);
+
 static struct vfio_group *vfio_group_from_dev(struct device *dev)
 {
 	struct vfio_device *device;
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 0bd25ba6223d..5641dab72ded 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -108,6 +108,13 @@ extern struct vfio_info_cap_header *vfio_info_cap_add(
 		struct vfio_info_cap *caps, size_t size, u16 id, u16 version);
 extern void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset);
 
+extern int vfio_info_add_capability(struct vfio_region_info *info,
+				    struct vfio_info_cap *caps,
+				    int cap_type_id, void *cap_type);
+
+extern int vfio_set_irqs_validate_and_prepare(struct vfio_irq_set *hdr,
+					      int num_irqs, int *data_size);
+
 struct pci_dev;
 #ifdef CONFIG_EEH
 extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);
