[PATCH v3 05/10] 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 IOMMU supports dirty tracking.

The auto domain logic allows different IOMMU domains to be created when DMA
dirty tracking is not desired (and VF can provide it) while others doesn't have
it and want the IOMMU capability. This is not used in this way here given how
VFIODevice migration capability checking takes place *after* the device
attachment. But such granularity is a nice property that can be implemented
later on.

Signed-off-by: Joao Martins <joao.m.mart...@oracle.com>
---
 include/hw/vfio/vfio-common.h |  1 +
 hw/vfio/iommufd.c             | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 82c5a4aaa61e..7ce925cfab19 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -97,6 +97,7 @@ typedef struct IOMMUFDBackend IOMMUFDBackend;
 
 typedef struct VFIOIOASHwpt {
     uint32_t hwpt_id;
+    uint32_t hwpt_flags;
     QLIST_HEAD(, VFIODevice) device_list;
     QLIST_ENTRY(VFIOIOASHwpt) next;
 } VFIOIOASHwpt;
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 2ca9a32cc7b6..1b5b46d28ed6 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -212,6 +212,20 @@ static bool iommufd_cdev_detach_ioas_hwpt(VFIODevice 
*vbasedev, Error **errp)
     return true;
 }
 
+static bool iommufd_device_dirty_tracking(IOMMUFDBackend *iommufd,
+                                          VFIODevice *vbasedev)
+{
+    enum iommu_hw_info_type type;
+    uint64_t caps;
+
+    if (!iommufd_backend_get_device_info(iommufd, vbasedev->devid, &type,
+                                         NULL, 0, &caps, NULL)) {
+        return false;
+    }
+
+    return caps & IOMMU_HW_CAP_DIRTY_TRACKING;
+}
+
 static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
                                          VFIOIOMMUFDContainer *container,
                                          Error **errp)
@@ -239,6 +253,15 @@ static bool iommufd_cdev_autodomains_get(VFIODevice 
*vbasedev,
         }
     }
 
+    /*
+     * This is quite early and VFIODevice isn't yet fully initialized,
+     * thus rely on IOMMU hardware capabilities as to whether IOMMU dirty
+     * tracking is going to be needed.
+     */
+    if (iommufd_device_dirty_tracking(iommufd, vbasedev)) {
+        flags = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
+    }
+
     ret = iommufd_backend_alloc_hwpt(iommufd,
                                      vbasedev->devid,
                                      container->ioas_id, flags,
@@ -255,6 +278,7 @@ static bool iommufd_cdev_autodomains_get(VFIODevice 
*vbasedev,
 
     hwpt = g_malloc0(sizeof(*hwpt));
     hwpt->hwpt_id = hwpt_id;
+    hwpt->hwpt_flags = flags;
     QLIST_INIT(&hwpt->device_list);
 
     ret = iommufd_cdev_attach_ioas_hwpt(vbasedev, hwpt->hwpt_id, errp);
@@ -267,6 +291,8 @@ static bool 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 true;
 }
 
-- 
2.17.2