Re: [PATCH v3 10/13] vfio/common: Add device dirty page bitmap sync

[Joao Martins <joao.m.martins@oracle.com>]

On 06/03/2023 19:22, Alex Williamson wrote:
> On Sat,  4 Mar 2023 01:43:40 +0000
> Joao Martins <joao.m.martins@oracle.com> wrote:
> 
>> Add device dirty page bitmap sync functionality. This uses the device
>> DMA logging uAPI to sync dirty page bitmap from the device.
>>
>> Device dirty page bitmap sync is used only if all devices within a
>> container support device dirty page tracking.
>>
>> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>> ---
>>  hw/vfio/common.c | 88 +++++++++++++++++++++++++++++++++++++++++++-----
>>  1 file changed, 79 insertions(+), 9 deletions(-)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index b0c7d03279ab..5b8456975e97 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -342,6 +342,9 @@ static int vfio_bitmap_alloc(VFIOBitmap *vbmap, hwaddr size)
>>      return 0;
>>  }
>>  
>> +static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
>> +                                 uint64_t size, ram_addr_t ram_addr);
>> +
>>  bool vfio_mig_active(void)
>>  {
>>      VFIOGroup *group;
>> @@ -565,10 +568,16 @@ static int vfio_dma_unmap(VFIOContainer *container,
>>          .iova = iova,
>>          .size = size,
>>      };
>> +    bool need_dirty_sync = false;
>> +    int ret;
>> +
>> +    if (iotlb && vfio_devices_all_running_and_mig_active(container)) {
>> +        if (!vfio_devices_all_device_dirty_tracking(container) &&
>> +            container->dirty_pages_supported) {
>> +            return vfio_dma_unmap_bitmap(container, iova, size, iotlb);
>> +        }
>>  
>> -    if (iotlb && container->dirty_pages_supported &&
>> -        vfio_devices_all_running_and_mig_active(container)) {
>> -        return vfio_dma_unmap_bitmap(container, iova, size, iotlb);
>> +        need_dirty_sync = true;
>>      }
>>  
>>      while (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap)) {
>> @@ -594,10 +603,12 @@ static int vfio_dma_unmap(VFIOContainer *container,
>>          return -errno;
>>      }
>>  
>> -    if (iotlb && vfio_devices_all_running_and_mig_active(container)) {
>> -        cpu_physical_memory_set_dirty_range(iotlb->translated_addr, size,
>> -                                            tcg_enabled() ? DIRTY_CLIENTS_ALL :
>> -                                            DIRTY_CLIENTS_NOCODE);
>> +    if (need_dirty_sync) {
>> +        ret = vfio_get_dirty_bitmap(container, iova, size,
>> +                                    iotlb->translated_addr);
>> +        if (ret) {
>> +            return ret;
>> +        }
>>      }
>>  
>>      return 0;
>> @@ -1579,6 +1590,58 @@ static void vfio_listener_log_global_stop(MemoryListener *listener)
>>      }
>>  }
>>  
>> +static int vfio_device_dma_logging_report(VFIODevice *vbasedev, hwaddr iova,
>> +                                          hwaddr size, void *bitmap)
>> +{
>> +    uint64_t buf[DIV_ROUND_UP(sizeof(struct vfio_device_feature) +
>> +                        sizeof(struct vfio_device_feature_dma_logging_report),
>> +                        sizeof(__aligned_u64))] = {};
>> +    struct vfio_device_feature *feature = (struct vfio_device_feature *)buf;
>> +    struct vfio_device_feature_dma_logging_report *report =
>> +        (struct vfio_device_feature_dma_logging_report *)feature->data;
>> +
>> +    report->iova = iova;
>> +    report->length = size;
>> +    report->page_size = qemu_real_host_page_size();
>> +    report->bitmap = (__aligned_u64)bitmap;
>> +
>> +    feature->argsz = sizeof(buf);
>> +    feature->flags =
>> +        VFIO_DEVICE_FEATURE_GET | VFIO_DEVICE_FEATURE_DMA_LOGGING_REPORT;
> 
> Nit, the series is inconsistent between initializing flags as above and
> as:
> 
>     feature->flags = VFIO_DEVICE_FEATURE_GET;
>     feature->flags |= VFIO_DEVICE_FEATURE_DMA_LOGGING_REPORT;
> 
> My personal preference would be more like:
> 
>     feature->flags = VFIO_DEVICE_FEATURE_GET |
>                      VFIO_DEVICE_FEATURE_DMA_LOGGING_REPORT;
>

I'll switch the overall style to the latter.

> Thanks,
> Alex
> 
>> +
>> +    if (ioctl(vbasedev->fd, VFIO_DEVICE_FEATURE, feature)) {
>> +        return -errno;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int vfio_devices_query_dirty_bitmap(VFIOContainer *container,
>> +                                           VFIOBitmap *vbmap, hwaddr iova,
>> +                                           hwaddr size)
>> +{
>> +    VFIODevice *vbasedev;
>> +    VFIOGroup *group;
>> +    int ret;
>> +
>> +    QLIST_FOREACH(group, &container->group_list, container_next) {
>> +        QLIST_FOREACH(vbasedev, &group->device_list, next) {
>> +            ret = vfio_device_dma_logging_report(vbasedev, iova, size,
>> +                                                 vbmap->bitmap);
>> +            if (ret) {
>> +                error_report("%s: Failed to get DMA logging report, iova: "
>> +                             "0x%" HWADDR_PRIx ", size: 0x%" HWADDR_PRIx
>> +                             ", err: %d (%s)",
>> +                             vbasedev->name, iova, size, ret, strerror(-ret));
>> +
>> +                return ret;
>> +            }
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>  static int vfio_query_dirty_bitmap(VFIOContainer *container, VFIOBitmap *vbmap,
>>                                     hwaddr iova, hwaddr size)
>>  {
>> @@ -1619,10 +1682,12 @@ static int vfio_query_dirty_bitmap(VFIOContainer *container, VFIOBitmap *vbmap,
>>  static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
>>                                   uint64_t size, ram_addr_t ram_addr)
>>  {
>> +    bool all_device_dirty_tracking =
>> +        vfio_devices_all_device_dirty_tracking(container);
>>      VFIOBitmap vbmap;
>>      int ret;
>>  
>> -    if (!container->dirty_pages_supported) {
>> +    if (!container->dirty_pages_supported && !all_device_dirty_tracking) {
>>          cpu_physical_memory_set_dirty_range(ram_addr, size,
>>                                              tcg_enabled() ? DIRTY_CLIENTS_ALL :
>>                                              DIRTY_CLIENTS_NOCODE);
>> @@ -1634,7 +1699,12 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
>>          return -errno;
>>      }
>>  
>> -    ret = vfio_query_dirty_bitmap(container, &vbmap, iova, size);
>> +    if (all_device_dirty_tracking) {
>> +        ret = vfio_devices_query_dirty_bitmap(container, &vbmap, iova, size);
>> +    } else {
>> +        ret = vfio_query_dirty_bitmap(container, &vbmap, iova, size);
>> +    }
>> +
>>      if (ret) {
>>          goto out;
>>      }
>