vfio/iommufd: Make a separate call to get IOMMU capabilities

Currently we depend on .realize() calling iommufd_backend_get_device_info()
to get IOMMU capabilities and check for dirty page tracking support.

By make a extra separate call, this dependency is removed. This happens
only during device attach, it's not a hot path.

Suggested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250423072824.3647952-2-zhenzhong.duan@intel.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 48db10542269111804643713270199657145accc..2253778b3ae0738f0a48dca77f0b68180b7d1f71 100644 (file)
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -287,7 +287,8 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
 {
     ERRP_GUARD();
     IOMMUFDBackend *iommufd = vbasedev->iommufd;
-    uint32_t flags = 0;
+    uint32_t type, flags = 0;
+    uint64_t hw_caps;
     VFIOIOASHwpt *hwpt;
     uint32_t hwpt_id;
     int ret;
@@ -324,7 +325,12 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
      * vfio_migration_realize() may decide to use VF dirty tracking
      * instead.
      */
-    if (vbasedev->hiod->caps.hw_caps & IOMMU_HW_CAP_DIRTY_TRACKING) {
+    if (!iommufd_backend_get_device_info(vbasedev->iommufd, vbasedev->devid,
+                                         &type, NULL, 0, &hw_caps, errp)) {
+        return false;
+    }
+
+    if (hw_caps & IOMMU_HW_CAP_DIRTY_TRACKING) {
         flags = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
     }