[qemu-s390x] [PATCH RFC] vfio-ap: flag as compatible with balloon

[Cornelia Huck]

vfio-ap devices do not pin any pages in the host. Therefore, they
are belived to be compatible with memory ballooning.

Flag them as compatible, so both vfio-ap and a balloon can be
used simultaneously.

Signed-off-by: Cornelia Huck <address@hidden>
---

As briefly discussed on IRC. RFC as I do not have easy access to
hardware I can test this with.

---
 hw/vfio/ap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
index 65de952f44..3bf48eed28 100644
--- a/hw/vfio/ap.c
+++ b/hw/vfio/ap.c
@@ -104,6 +104,14 @@ static void vfio_ap_realize(DeviceState *dev, Error **errp)
     vapdev->vdev.name = g_strdup_printf("%s", mdevid);
     vapdev->vdev.dev = dev;
 
+    /*
+     * vfio-ap devices are believed to operate in a way compatible with
+     * memory ballooning, as no pages are pinned in the host.
+     * This needs to be set before vfio_get_device() for vfio common to
+     * handle the balloon inhibitor.
+     */
+    vapdev->vdev.balloon_allowed = true;
+
     ret = vfio_get_device(vfio_group, mdevid, &vapdev->vdev, &local_err);
     if (ret) {
         goto out_get_dev_err;
-- 
2.17.2