Re: [PATCH v3 06/10] vfio/iommufd: Implement VFIOIOMMUClass::set_dirty_tracking support

["Cédric Le Goater" <clg@redhat.com>]

On 7/8/24 4:34 PM, Joao Martins wrote:
> ioctl(iommufd, IOMMU_HWPT_SET_DIRTY_TRACKING, arg) is the UAPI that
> enables or disables dirty page tracking. It 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
> it is are tracking. On failure it rolls it back.
> 
> The checking of hwpt::flags is introduced here as a second user
> and thus consolidate such check into a helper function
> iommufd_hwpt_dirty_tracking().
> 
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> ---
>   include/sysemu/iommufd.h |  3 +++
>   backends/iommufd.c       | 20 ++++++++++++++++++
>   hw/vfio/iommufd.c        | 45 +++++++++++++++++++++++++++++++++++++++-
>   backends/trace-events    |  1 +
>   4 files changed, 68 insertions(+), 1 deletion(-)
> 
> diff --git a/include/sysemu/iommufd.h b/include/sysemu/iommufd.h
> index 35a8cec9780f..1470377f55ba 100644
> --- a/include/sysemu/iommufd.h
> +++ b/include/sysemu/iommufd.h
> @@ -54,6 +54,9 @@ int iommufd_backend_alloc_hwpt(IOMMUFDBackend *be, uint32_t dev_id,
>                                  uint32_t pt_id, uint32_t flags,
>                                  uint32_t data_type, uint32_t data_len,
>                                  void *data_ptr, uint32_t *out_hwpt);
> +int iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
> +                                       bool start);
>   
>   #define TYPE_HOST_IOMMU_DEVICE_IOMMUFD TYPE_HOST_IOMMU_DEVICE "-iommufd"
> +
>   #endif
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index f5f73eaf4a1a..69daabc27473 100644
> --- a/backends/iommufd.c
> +++ b/backends/iommufd.c
> @@ -237,6 +237,26 @@ int iommufd_backend_alloc_hwpt(IOMMUFDBackend *be, uint32_t dev_id,
>       return ret;
>   }
>   
> +int iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
> +                                       bool start)
> +{
> +    int ret;
> +    struct iommu_hwpt_set_dirty_tracking set_dirty = {
> +            .size = sizeof(set_dirty),
> +            .hwpt_id = hwpt_id,
> +            .flags = !start ? 0 : IOMMU_HWPT_DIRTY_TRACKING_ENABLE,
> +    };
> +
> +    ret = ioctl(be->fd, IOMMU_HWPT_SET_DIRTY_TRACKING, &set_dirty);
> +    trace_iommufd_backend_set_dirty(be->fd, hwpt_id, start, ret);
> +    if (ret) {
> +        ret = -errno;
> +        error_report("IOMMU_HWPT_SET_DIRTY_TRACKING failed: %s",
> +                     strerror(errno));
> +    }
> +    return ret;
> +}
> +
>   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 1b5b46d28ed6..158a98cb3b12 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -110,6 +110,48 @@ 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_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);
> +    int ret;
> +    VFIOIOASHwpt *hwpt;
> +
> +    QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
> +        if (!iommufd_hwpt_dirty_tracking(hwpt)) {
> +            continue;
> +        }
> +
> +        ret = iommufd_backend_set_dirty_tracking(container->be,
> +                                                 hwpt->hwpt_id, start);
> +        if (ret) {
> +            ret = -errno;
> +            error_setg_errno(errp, errno,
> +                             "Failed to start dirty tracking on hwpt_id %u",
> +                             hwpt->hwpt_id);



This error looks redundant with the one printed out in the lower backend
version. Couldn't we add an 'Error **' parameter and return a bool ?


Thanks,

C.

> +            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);
> +    }
> +    return ret;
> +}
> +
>   static int iommufd_cdev_getfd(const char *sysfs_path, Error **errp)
>   {
>       ERRP_GUARD();
> @@ -292,7 +334,7 @@ static bool iommufd_cdev_autodomains_get(VFIODevice *vbasedev,
>       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);
> +                              iommufd_hwpt_dirty_tracking(hwpt);
>       return true;
>   }
>   
> @@ -734,6 +776,7 @@ 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)"