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

[Alex Williamson]

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;

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;
>      }