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

[Joao Martins]

On 09/07/2024 08:07, Cédric Le Goater wrote:
> 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 ?

I'll add here as well.

        Joao