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

[Eric Auger]

Hi Joao,

On 7/12/24 13:47, Joao Martins wrote:
> Probe hardware dirty tracking support by querying device hw capabilities via
> IOMMUFD_GET_HW_INFO.
this is not what the patch brings. GET_HW_INFO is always in place.
>
> In preparation to using the dirty tracking UAPI, request dirty tracking in the
> HWPT flags when the IOMMU supports dirty tracking.
this is what the patch brings.
>
> 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
don't
> 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.
Id on't understand the above sentence

Eric
>
> Signed-off-by: Joao Martins <joao.m.martins@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,
so what's the problem exactly with the above?
> +     * 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;
>  }
>