vhost: vdpa: report iova range

This patch introduces a new ioctl for vhost-vdpa device that can
report the iova range by the device.

For device that implements get_iova_range() method, we fetch it from
the vDPA device. If device doesn't implement get_iova_range() but
depends on platform IOMMU, we will query via DOMAIN_ATTR_GEOMETRY,
otherwise [0, ULLONG_MAX] is assumed.

For safety, this patch also rules out the map request which is not in
the valid range.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20201023090043.14430-3-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vdpa.c

@@ -47,6 +47,7 @@ struct vhost_vdpa {
 	int minor;
 	struct eventfd_ctx *config_ctx;
 	int in_batch;
+	struct vdpa_iova_range range;
 };
 
 static DEFINE_IDA(vhost_vdpa_ida);
@@ -337,6 +338,16 @@ static long vhost_vdpa_set_config_call(struct vhost_vdpa *v, u32 __user *argp)
 	return 0;
 }
 
+static long vhost_vdpa_get_iova_range(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vhost_vdpa_iova_range range = {
+		.first = v->range.first,
+		.last = v->range.last,
+	};
+
+	return copy_to_user(argp, &range, sizeof(range));
+}
+
 static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 				   void __user *argp)
 {
@@ -471,6 +482,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 		features = VHOST_VDPA_BACKEND_FEATURES;
 		r = copy_to_user(featurep, &features, sizeof(features));
 		break;
+	case VHOST_VDPA_GET_IOVA_RANGE:
+		r = vhost_vdpa_get_iova_range(v, argp);
+		break;
 	default:
 		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
 		if (r == -ENOIOCTLCMD)
@@ -597,6 +611,10 @@ static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
 	long pinned;
 	int ret = 0;
 
+	if (msg->iova < v->range.first ||
+	    msg->iova + msg->size - 1 > v->range.last)
+		return -EINVAL;
+
 	if (vhost_iotlb_itree_first(iotlb, msg->iova,
 				    msg->iova + msg->size - 1))
 		return -EEXIST;
@@ -783,6 +801,27 @@ static void vhost_vdpa_free_domain(struct vhost_vdpa *v)
 	v->domain = NULL;
 }
 
+static void vhost_vdpa_set_iova_range(struct vhost_vdpa *v)
+{
+	struct vdpa_iova_range *range = &v->range;
+	struct iommu_domain_geometry geo;
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (ops->get_iova_range) {
+		*range = ops->get_iova_range(vdpa);
+	} else if (v->domain &&
+		   !iommu_domain_get_attr(v->domain,
+		   DOMAIN_ATTR_GEOMETRY, &geo) &&
+		   geo.force_aperture) {
+		range->first = geo.aperture_start;
+		range->last = geo.aperture_end;
+	} else {
+		range->first = 0;
+		range->last = ULLONG_MAX;
+	}
+}
+
 static int vhost_vdpa_open(struct inode *inode, struct file *filep)
 {
 	struct vhost_vdpa *v;
@@ -823,6 +862,8 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
 	if (r)
 		goto err_init_iotlb;
 
+	vhost_vdpa_set_iova_range(v);
+
 	filep->private_data = v;
 
 	return 0;

include/uapi/linux/vhost.h

@@ -146,4 +146,8 @@
 
 /* Set event fd for config interrupt*/
 #define VHOST_VDPA_SET_CONFIG_CALL	_IOW(VHOST_VIRTIO, 0x77, int)
+
+/* Get the valid iova range */
+#define VHOST_VDPA_GET_IOVA_RANGE	_IOR(VHOST_VIRTIO, 0x78, \
+					     struct vhost_vdpa_iova_range)
 #endif

include/uapi/linux/vhost_types.h

@@ -138,6 +138,15 @@ struct vhost_vdpa_config {
 	__u8 buf[0];
 };
 
+/* vhost vdpa IOVA range
+ * @first: First address that can be mapped by vhost-vDPA
+ * @last: Last address that can be mapped by vhost-vDPA
+ */
+struct vhost_vdpa_iova_range {
+	__u64 first;
+	__u64 last;
+};
+
 /* Feature bits */
 /* Log all write descriptors. Can be changed while device is active. */
 #define VHOST_F_LOG_ALL 26