Re: [PATCH v6 6/9] vfio/iommufd: Implement VFIOIOMMUClass::set_dirty_tracking support

[Eric Auger]

Hi Joao,

On 7/22/24 23:13, Joao Martins wrote:
> ioctl(iommufd, IOMMU_HWPT_SET_DIRTY_TRACKING, arg) is the UAPI that
> enables or disables dirty page tracking. The ioctl is used if the hwpt
> has been created with dirty tracking supported domain (stored in
> hwpt::flags) and it is called on the whole list of iommu domains.
>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
>  include/sysemu/iommufd.h |  2 ++
>  backends/iommufd.c       | 23 +++++++++++++++++++++++
>  hw/vfio/iommufd.c        | 32 ++++++++++++++++++++++++++++++++
>  backends/trace-events    |  1 +
>  4 files changed, 58 insertions(+)
>
> diff --git a/include/sysemu/iommufd.h b/include/sysemu/iommufd.h
> index e917e7591d05..6fb412f61144 100644
> --- a/include/sysemu/iommufd.h
> +++ b/include/sysemu/iommufd.h
> @@ -55,6 +55,8 @@ bool iommufd_backend_alloc_hwpt(IOMMUFDBackend *be, 
> uint32_t dev_id,
>                                  uint32_t data_type, uint32_t data_len,
>                                  void *data_ptr, uint32_t *out_hwpt,
>                                  Error **errp);
> +bool iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
> +                                        bool start, Error **errp);
>  
>  #define TYPE_HOST_IOMMU_DEVICE_IOMMUFD TYPE_HOST_IOMMU_DEVICE "-iommufd"
>  #endif
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index 06b135111f30..b97883503884 100644
> --- a/backends/iommufd.c
> +++ b/backends/iommufd.c
> @@ -238,6 +238,29 @@ bool iommufd_backend_alloc_hwpt(IOMMUFDBackend *be, 
> uint32_t dev_id,
>      return true;
>  }
>  
> +bool iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be,
> +                                        uint32_t hwpt_id, bool start,
> +                                        Error **errp)
> +{
> +    int ret;
> +    struct iommu_hwpt_set_dirty_tracking set_dirty = {
> +            .size = sizeof(set_dirty),
> +            .hwpt_id = hwpt_id,
> +            .flags = start ? IOMMU_HWPT_DIRTY_TRACKING_ENABLE : 0,
> +    };
> +
> +    ret = ioctl(be->fd, IOMMU_HWPT_SET_DIRTY_TRACKING, &set_dirty);
> +    trace_iommufd_backend_set_dirty(be->fd, hwpt_id, start, ret ? errno : 0);
> +    if (ret) {
> +        error_setg_errno(errp, errno,
> +                         "IOMMU_HWPT_SET_DIRTY_TRACKING(hwpt_id %u) failed",
> +                         hwpt_id);
> +        return false;
> +    }
> +
> +    return true;
> +}
> +
>  bool iommufd_backend_get_device_info(IOMMUFDBackend *be, uint32_t devid,
>                                       uint32_t *type, void *data, uint32_t 
> len,
>                                       uint64_t *caps, Error **errp)
> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
> index 7afea0b041ed..b882a3f59a6e 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -115,6 +115,37 @@ static bool iommufd_hwpt_dirty_tracking(VFIOIOASHwpt 
> *hwpt)
>      return hwpt && hwpt->hwpt_flags & IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
>  }
>  
> +static int iommufd_set_dirty_page_tracking(const VFIOContainerBase 
> *bcontainer,
> +                                           bool start, Error **errp)
> +{
> +    const VFIOIOMMUFDContainer *container =
> +        container_of(bcontainer, VFIOIOMMUFDContainer, bcontainer);
> +    VFIOIOASHwpt *hwpt;
> +
> +    QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
> +        if (!iommufd_hwpt_dirty_tracking(hwpt)) {
> +            continue;
> +        }
so here I see you handle the case where we have hwpts with and without
support for dirty tracking within the same container so I guess this
answers my previous question. So do you want to tag a container as
dirty_pages_supported = true as soon as one device is backed up with a
dirty tracking hwpt within that container? I think I miss the high level
view of when this case may happen and why the devices do not end up in
different containers/ioas. But maybe I completely mix up things &
objects. Eric
> +
> +        if (!iommufd_backend_set_dirty_tracking(container->be,
> +                                                hwpt->hwpt_id, start, errp)) 
> {
> +            goto err;
> +        }
> +    }
> +
> +    return 0;
> +
> +err:
> +    QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
> +        if (!iommufd_hwpt_dirty_tracking(hwpt)) {
> +            continue;
> +        }
> +        iommufd_backend_set_dirty_tracking(container->be,
> +                                           hwpt->hwpt_id, !start, NULL);
> +    }
> +    return -EINVAL;
> +}
> +
>  static int iommufd_cdev_getfd(const char *sysfs_path, Error **errp)
>  {
>      ERRP_GUARD();
> @@ -725,6 +756,7 @@ static void vfio_iommu_iommufd_class_init(ObjectClass 
> *klass, void *data)
>      vioc->attach_device = iommufd_cdev_attach;
>      vioc->detach_device = iommufd_cdev_detach;
>      vioc->pci_hot_reset = iommufd_cdev_pci_hot_reset;
> +    vioc->set_dirty_page_tracking = iommufd_set_dirty_page_tracking;
>  };
>  
>  static bool hiod_iommufd_vfio_realize(HostIOMMUDevice *hiod, void *opaque,
> diff --git a/backends/trace-events b/backends/trace-events
> index 4d8ac02fe7d6..28aca3b859d4 100644
> --- a/backends/trace-events
> +++ b/backends/trace-events
> @@ -16,3 +16,4 @@ iommufd_backend_unmap_dma(int iommufd, uint32_t ioas, 
> uint64_t iova, uint64_t si
>  iommufd_backend_alloc_ioas(int iommufd, uint32_t ioas) " iommufd=%d ioas=%d"
>  iommufd_backend_alloc_hwpt(int iommufd, uint32_t dev_id, uint32_t pt_id, 
> uint32_t flags, uint32_t hwpt_type, uint32_t len, uint64_t data_ptr, uint32_t 
> out_hwpt_id, int ret) " iommufd=%d dev_id=%u pt_id=%u flags=0x%x hwpt_type=%u 
> len=%u data_ptr=0x%"PRIx64" out_hwpt=%u (%d)"
>  iommufd_backend_free_id(int iommufd, uint32_t id, int ret) " iommufd=%d 
> id=%d (%d)"
> +iommufd_backend_set_dirty(int iommufd, uint32_t hwpt_id, bool start, int 
> ret) " iommufd=%d hwpt=%u enable=%d (%d)"