[PATCH RFCv2 3/8] vfio/iommufd: Probe and request hwpt dirty tracking capability

[Joao Martins]

Probe hardware dirty tracking support by querying device hw capabilities
via IOMMUFD_GET_HW_INFO.

In preparation to using the dirty tracking UAPI, request dirty tracking in
the HWPT flags when the device doesn't support dirty page tracking or has
it disabled; or when support when the VF backing IOMMU supports dirty
tracking. The latter is in the possibility of a device being attached
that doesn't have a dirty tracker.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 hw/vfio/common.c              | 18 ++++++++++++++++++
 hw/vfio/iommufd.c             | 25 ++++++++++++++++++++++++-
 include/hw/vfio/vfio-common.h |  2 ++
 3 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index f7f85160be88..d8fc7077f839 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -216,6 +216,24 @@ bool vfio_devices_all_device_dirty_tracking(const 
VFIOContainerBase *bcontainer)
     return true;
 }
 
+bool vfio_device_migration_supported(VFIODevice *vbasedev)
+{
+    if (!vbasedev->migration) {
+        return false;
+    }
+
+    return vbasedev->migration->mig_flags & VFIO_MIGRATION_STOP_COPY;
+}
+
+bool vfio_device_dirty_pages_supported(VFIODevice *vbasedev)
+{
+    if (vbasedev->pre_copy_dirty_page_tracking == ON_OFF_AUTO_OFF) {
+        return false;
+    }
+
+    return !vbasedev->dirty_pages_supported;
+}
+
 /*
  * Check if all VFIO devices are running and migration is active, which is
  * essentially equivalent to the migration being in pre-copy phase.
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index ca7ec45e725c..edacb6d72748 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -219,11 +219,26 @@ static int iommufd_cdev_detach_ioas_hwpt(VFIODevice 
*vbasedev, Error **errp)
     return ret;
 }
 
+static bool iommufd_dirty_pages_supported(IOMMUFDDevice *iommufd_dev,
+                                          Error **errp)
+{
+    uint64_t caps;
+    int r;
+
+    r = iommufd_device_get_hw_capabilities(iommufd_dev, &caps, errp);
+    if (r) {
+        return false;
+    }
+
+    return caps & IOMMU_HW_CAP_DIRTY_TRACKING;
+}
+
 static int iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
                                         VFIOIOMMUFDContainer *container,
                                         Error **errp)
 {
     int iommufd = vbasedev->iommufd_dev.iommufd->fd;
+    uint32_t flags = 0;
     VFIOIOASHwpt *hwpt;
     Error *err = NULL;
     int ret = -EINVAL;
@@ -245,9 +260,15 @@ static int iommufd_cdev_autodomains_get(VFIODevice 
*vbasedev,
         }
     }
 
+    if ((vfio_device_migration_supported(vbasedev) &&
+         !vfio_device_dirty_pages_supported(vbasedev)) ||
+        iommufd_dirty_pages_supported(&vbasedev->iommufd_dev, &err)) {
+        flags = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
+    }
+
     ret = iommufd_backend_alloc_hwpt(iommufd,
                                      vbasedev->iommufd_dev.devid,
-                                     container->ioas_id, 0, 0, 0,
+                                     container->ioas_id, flags, 0, 0,
                                      NULL, &hwpt_id);
     if (ret) {
         error_append_hint(&err,
@@ -271,6 +292,8 @@ static int iommufd_cdev_autodomains_get(VFIODevice 
*vbasedev,
     vbasedev->hwpt = hwpt;
     QLIST_INSERT_HEAD(&hwpt->device_list, vbasedev, hwpt_next);
     QLIST_INSERT_HEAD(&container->hwpt_list, hwpt, next);
+    container->bcontainer.dirty_pages_supported =
+                              (flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING);
     return 0;
 }
 
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 7f7d823221e2..a3e691c126c6 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -271,6 +271,8 @@ bool
 vfio_devices_all_running_and_mig_active(const VFIOContainerBase *bcontainer);
 bool
 vfio_devices_all_device_dirty_tracking(const VFIOContainerBase *bcontainer);
+bool vfio_device_migration_supported(VFIODevice *vbasedev);
+bool vfio_device_dirty_pages_supported(VFIODevice *vbasedev);
 int vfio_devices_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
                                     VFIOBitmap *vbmap, hwaddr iova,
                                     hwaddr size);
-- 
2.39.3