Re: [PATCH v4 09/12] vfio/iommufd: Implement VFIOIOMMUClass::set_dirty_tracking support

[Eric Auger <eric.auger@redhat.com>]

On 7/17/24 14:41, Joao Martins wrote:
> On 17/07/2024 13:36, Eric Auger wrote:
>>
>> On 7/12/24 13:47, 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.
>> it is are tracking ?
> *it is*
>
>> also please clearly state what is "it"
>>
> sure
>
>>> The checking of hwpt::flags is introduced here as a second user
>> ?? -> introduce iommufd_hwpt_dirty_tracking() helper to avoid code dup?
> Right I am doing that already. Not sure what the problem is with this sentence?

"The checking of hwpt::flags is introduced here as a second user" phrasing sounds weird to me.
I guess you just meant that you need to check 
hwpt::flags in another place so better off introducing an helper.

>
> Or you meant to use yours as it's simpler/easier to understand.
>
>>> 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       | 23 +++++++++++++++++++++++
>>>  hw/vfio/iommufd.c        | 39 ++++++++++++++++++++++++++++++++++++++-
>>>  backends/trace-events    |  1 +
>>>  4 files changed, 65 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/include/sysemu/iommufd.h b/include/sysemu/iommufd.h
>>> index e917e7591d05..7416d9219703 100644
>>> --- a/include/sysemu/iommufd.h
>>> +++ b/include/sysemu/iommufd.h
>>> @@ -55,6 +55,9 @@ 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"
>>> +
>> spurious line change
> ok
>
>>>  #endif
>>> diff --git a/backends/iommufd.c b/backends/iommufd.c
>>> index 41a9dec3b2c5..239f0976e0ad 100644
>>> --- a/backends/iommufd.c
>>> +++ b/backends/iommufd.c
>>> @@ -239,6 +239,29 @@ 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 ? 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 ? 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 edc8f97d8f3d..da678315faeb 100644
>>> --- a/hw/vfio/iommufd.c
>>> +++ b/hw/vfio/iommufd.c
>>> @@ -110,6 +110,42 @@ 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);
>>> +    VFIOIOASHwpt *hwpt;
>>> +
>>> +    QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
>>> +        if (!iommufd_hwpt_dirty_tracking(hwpt)) {
>>> +            continue;
>>> +        }
>>> +
>>> +        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();
>>> @@ -278,7 +314,7 @@ 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;
>>>  }
>>>  
>>> @@ -717,6 +753,7 @@ 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)"