vduse: Support querying information of IOVA regions

This introduces a new ioctl: VDUSE_IOTLB_GET_INFO to
support querying some information of IOVA regions.

Now it can be used to query whether the IOVA region
supports userspace memory registration.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Message-Id: <20220803045523.23851-6-xieyongji@bytedance.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index eedff0a..41c0b29 100644 (file)
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -1228,6 +1228,45 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
                                           umem.size);
                break;
        }
+       case VDUSE_IOTLB_GET_INFO: {
+               struct vduse_iova_info info;
+               struct vhost_iotlb_map *map;
+               struct vduse_iova_domain *domain = dev->domain;
+
+               ret = -EFAULT;
+               if (copy_from_user(&info, argp, sizeof(info)))
+                       break;
+
+               ret = -EINVAL;
+               if (info.start > info.last)
+                       break;
+
+               if (!is_mem_zero((const char *)info.reserved,
+                                sizeof(info.reserved)))
+                       break;
+
+               spin_lock(&domain->iotlb_lock);
+               map = vhost_iotlb_itree_first(domain->iotlb,
+                                             info.start, info.last);
+               if (map) {
+                       info.start = map->start;
+                       info.last = map->last;
+                       info.capability = 0;
+                       if (domain->bounce_map && map->start == 0 &&
+                           map->last == domain->bounce_size - 1)
+                               info.capability |= VDUSE_IOVA_CAP_UMEM;
+               }
+               spin_unlock(&domain->iotlb_lock);
+               if (!map)
+                       break;
+
+               ret = -EFAULT;
+               if (copy_to_user(argp, &info, sizeof(info)))
+                       break;
+
+               ret = 0;
+               break;
+       }
        default:
                ret = -ENOIOCTLCMD;
                break;

diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
index 9885e05..11bd48c 100644 (file)
--- a/include/uapi/linux/vduse.h
+++ b/include/uapi/linux/vduse.h
@@ -233,6 +233,30 @@ struct vduse_iova_umem {
 /* De-register the userspace memory. Caller should set iova and size field. */
 #define VDUSE_IOTLB_DEREG_UMEM _IOW(VDUSE_BASE, 0x19, struct vduse_iova_umem)
 
+/**
+ * struct vduse_iova_info - information of one IOVA region
+ * @start: start of the IOVA region
+ * @last: last of the IOVA region
+ * @capability: capability of the IOVA regsion
+ * @reserved: for future use, needs to be initialized to zero
+ *
+ * Structure used by VDUSE_IOTLB_GET_INFO ioctl to get information of
+ * one IOVA region.
+ */
+struct vduse_iova_info {
+       __u64 start;
+       __u64 last;
+#define VDUSE_IOVA_CAP_UMEM (1 << 0)
+       __u64 capability;
+       __u64 reserved[3];
+};
+
+/*
+ * Find the first IOVA region that overlaps with the range [start, last]
+ * and return some information on it. Caller should set start and last fields.
+ */
+#define VDUSE_IOTLB_GET_INFO   _IOWR(VDUSE_BASE, 0x1a, struct vduse_iova_info)
+
 /* The control messages definition for read(2)/write(2) on /dev/vduse/$NAME */
 
 /**