vfio/pci: Introduce vfio_[attach/detach]_device

We want the VFIO devices to be able to use two different
IOMMU backends, the legacy VFIO one and the new iommufd one.

Introduce vfio_[attach/detach]_device which aim at hiding the
underlying IOMMU backend (IOCTLs, datatypes, ...).

Once vfio_attach_device completes, the device is attached
to a security context and its fd can be used. Conversely
When vfio_detach_device completes, the device has been
detached from the security context.

At the moment only the implementation based on the legacy
container/group exists. Let's use it from the vfio-pci device.
Subsequent patches will handle other devices.

We also take benefit of this patch to properly free
vbasedev->name on failure.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index d8ed432..f4c33c9 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -2611,3 +2611,77 @@ int vfio_eeh_as_op(AddressSpace *as, uint32_t op)
     }
     return vfio_eeh_container_op(container, op);
 }
+
+static int vfio_device_groupid(VFIODevice *vbasedev, Error **errp)
+{
+    char *tmp, group_path[PATH_MAX], *group_name;
+    int ret, groupid;
+    ssize_t len;
+
+    tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev);
+    len = readlink(tmp, group_path, sizeof(group_path));
+    g_free(tmp);
+
+    if (len <= 0 || len >= sizeof(group_path)) {
+        ret = len < 0 ? -errno : -ENAMETOOLONG;
+        error_setg_errno(errp, -ret, "no iommu_group found");
+        return ret;
+    }
+
+    group_path[len] = 0;
+
+    group_name = basename(group_path);
+    if (sscanf(group_name, "%d", &groupid) != 1) {
+        error_setg_errno(errp, errno, "failed to read %s", group_path);
+        return -errno;
+    }
+    return groupid;
+}
+
+/*
+ * vfio_attach_device: attach a device to a security context
+ * @name and @vbasedev->name are likely to be different depending
+ * on the type of the device, hence the need for passing @name
+ */
+int vfio_attach_device(char *name, VFIODevice *vbasedev,
+                       AddressSpace *as, Error **errp)
+{
+    int groupid = vfio_device_groupid(vbasedev, errp);
+    VFIODevice *vbasedev_iter;
+    VFIOGroup *group;
+    int ret;
+
+    if (groupid < 0) {
+        return groupid;
+    }
+
+    trace_vfio_attach_device(vbasedev->name, groupid);
+
+    group = vfio_get_group(groupid, as, errp);
+    if (!group) {
+        return -ENOENT;
+    }
+
+    QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
+        if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) {
+            error_setg(errp, "device is already attached");
+            vfio_put_group(group);
+            return -EBUSY;
+        }
+    }
+    ret = vfio_get_device(group, name, vbasedev, errp);
+    if (ret) {
+        vfio_put_group(group);
+    }
+
+    return ret;
+}
+
+void vfio_detach_device(VFIODevice *vbasedev)
+{
+    VFIOGroup *group = vbasedev->group;
+
+    trace_vfio_detach_device(vbasedev->name, group->groupid);
+    vfio_put_base_device(vbasedev);
+    vfio_put_group(group);
+}