Re: [PATCH v4 08/12] vfio/iommufd: Probe and request hwpt dirty tracking capability

[Cédric Le Goater]

On 7/12/24 13:47, Joao Martins wrote:

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.

Signed-off-by: Joao Martins <joao.m.mart...@oracle.com>
---
  include/hw/vfio/vfio-common.h |  1 +
  hw/vfio/iommufd.c             | 12 ++++++++++++
  2 files changed, 13 insertions(+)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 2dd468ce3c02..760f31d84ac8 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 d34dc88231ec..edc8f97d8f3d 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -246,6 +246,15 @@ 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 (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,
@@ -255,6 +264,7 @@ 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 +277,8 @@ 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;
  }

Could you please introduce in this patch helper :

  static bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt *hwpt)
  {
      return hwpt->hwpt_flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
  }



Thanks,

C.