vfio/iommufd: Probe and request hwpt dirty tracking capability

In preparation to using the dirty tracking UAPI, probe whether the IOMMU
supports dirty tracking. This is done via the data stored in
hiod::caps::hw_caps initialized from GET_HW_INFO.

Qemu doesn't know if VF dirty tracking is supported when allocating
hardware pagetable in iommufd_cdev_autodomains_get(). This is because
VFIODevice migration state hasn't been initialized *yet* hence it can't pick
between VF dirty tracking vs IOMMU dirty tracking. So, if IOMMU supports
dirty tracking it always creates HWPTs with IOMMU_HWPT_ALLOC_DIRTY_TRACKING
even if later on VFIOMigration decides to use VF dirty tracking instead.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
[ clg: - Fixed vbasedev->iommu_dirty_tracking assignment in
         iommufd_cdev_autodomains_get()
       - Added warning for heterogeneous dirty page tracking support
	 in iommufd_cdev_autodomains_get() ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

2 files changed, 28 insertions, 0 deletions

diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 798c479..240c476 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -110,6 +110,11 @@ static void iommufd_cdev_unbind_and_disconnect(VFIODevice *vbasedev)
     iommufd_backend_disconnect(vbasedev->iommufd);
 }
 
+static bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt *hwpt)
+{
+    return hwpt && hwpt->hwpt_flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
+}
+
 static int iommufd_cdev_getfd(const char *sysfs_path, Error **errp)
 {
     ERRP_GUARD();
@@ -243,10 +248,22 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
         } else {
             vbasedev->hwpt = hwpt;
             QLIST_INSERT_HEAD(&hwpt->device_list, vbasedev, hwpt_next);
+            vbasedev->iommu_dirty_tracking = iommufd_hwpt_dirty_tracking(hwpt);
             return true;
         }
     }
 
+    /*
+     * This is quite early and VFIO Migration state isn't yet fully
+     * initialized, thus rely only on IOMMU hardware capabilities as to
+     * whether IOMMU dirty tracking is going to be requested. Later
+     * vfio_migration_realize() may decide to use VF dirty tracking
+     * instead.
+     */
+    if (vbasedev->hiod->caps.hw_caps & IOMMU_HW_CAP_DIRTY_TRACKING) {
+        flags = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
+    }
+
     if (!iommufd_backend_alloc_hwpt(iommufd, vbasedev->devid,
                                     container->ioas_id, flags,
                                     IOMMU_HWPT_DATA_NONE, 0, NULL,
@@ -256,6 +273,7 @@ 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);
@@ -266,8 +284,16 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
     }
 
     vbasedev->hwpt = hwpt;
+    vbasedev->iommu_dirty_tracking = iommufd_hwpt_dirty_tracking(hwpt);
     QLIST_INSERT_HEAD(&hwpt->device_list, vbasedev, hwpt_next);
     QLIST_INSERT_HEAD(&container->hwpt_list, hwpt, next);
+    container->bcontainer.dirty_pages_supported |=
+                                vbasedev->iommu_dirty_tracking;
+    if (container->bcontainer.dirty_pages_supported &&
+        !vbasedev->iommu_dirty_tracking) {
+        warn_report("IOMMU instance for device %s doesn't support dirty tracking",
+                    vbasedev->name);
+    }
     return true;
 }
 
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 4e44b26..1e02c98 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;
@@ -139,6 +140,7 @@ typedef struct VFIODevice {
     OnOffAuto pre_copy_dirty_page_tracking;
     bool dirty_pages_supported;
     bool dirty_tracking;
+    bool iommu_dirty_tracking;
     HostIOMMUDevice *hiod;
     int devid;
     IOMMUFDBackend *iommufd;