vfio/container: Implement HostIOMMUDeviceClass::realize() handler

The realize function populates the capabilities. For now only the
aw_bits caps is computed for legacy backend.

Introduce a helper function vfio_device_get_aw_bits() which calls
range_get_last_bit() to get host aw_bits and package it in
HostIOMMUDeviceCaps for query with .get_cap(). This helper will
also be used by iommufd backend.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/hw/vfio/helpers.c b/hw/vfio/helpers.c
index 27ea26aa48..b14edd46ed 100644
--- a/hw/vfio/helpers.c
+++ b/hw/vfio/helpers.c
@@ -658,3 +658,20 @@ void vfio_device_init(VFIODevice *vbasedev, int type, VFIODeviceOps *ops,
 
     vbasedev->ram_block_discard_allowed = ram_discard;
 }
+
+int vfio_device_get_aw_bits(VFIODevice *vdev)
+{
+    /*
+     * iova_ranges is a sorted list. For old kernels that support
+     * VFIO but not support query of iova ranges, iova_ranges is NULL,
+     * in this case HOST_IOMMU_DEVICE_CAP_AW_BITS_MAX(64) is returned.
+     */
+    GList *l = g_list_last(vdev->bcontainer->iova_ranges);
+
+    if (l) {
+        Range *range = l->data;
+        return range_get_last_bit(range) + 1;
+    }
+
+    return HOST_IOMMU_DEVICE_CAP_AW_BITS_MAX;
+}