Re: [RFC PATCH 2/3] vfio: Add vfio_prereg_listener_log_sync in nested stage

[Auger Eric]

Hi Kunkun,

On 2/19/21 10:42 AM, Kunkun Jiang wrote:
> On Intel, the DMA mapped through the host single stage. Instead
> we set up the stage 2 and stage 1 separately in nested mode as there
> is no "Caching Mode".

You need to rewrite the above sentences, Missing ARM and also the 1st
sentences misses a verb.
> 
> Legacy vfio_listener_log_sync cannot be used in nested stage as we
> don't need to pay close attention to stage 1 mapping. This patch adds
> vfio_prereg_listener_log_sync to mark dirty pages in nested mode.
> 
> Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
> ---
>  hw/vfio/common.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 7c50905856..af333e0dee 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -1216,6 +1216,22 @@ static int 
> vfio_dma_sync_ram_section_dirty_bitmap(VFIOContainer *container,
>                         int128_get64(section->size), ram_addr);
>  }
>  
> +static void vfio_prereg_listener_log_sync(MemoryListener *listener,
> +                                          MemoryRegionSection *section)
> +{
> +    VFIOContainer *container =
> +        container_of(listener, VFIOContainer, prereg_listener);
> +
> +    if (!memory_region_is_ram(section->mr) ||
> +        !container->dirty_pages_supported) {
> +        return;
> +    }
> +
> +    if (vfio_devices_all_saving(container)) {
I fail to see where is this defined?
> +        vfio_dma_sync_ram_section_dirty_bitmap(container, section);
> +    }
> +}
> +
>  typedef struct {
>      IOMMUNotifier n;
>      VFIOGuestIOMMU *giommu;
> @@ -1260,6 +1276,14 @@ static int vfio_sync_dirty_bitmap(VFIOContainer 
> *container,
>      if (memory_region_is_iommu(section->mr)) {
>          VFIOGuestIOMMU *giommu;
>  
> +        /*
> +         * In nested mode, stage 2 and stage 1 are set up separately. We
> +         * only need to focus on stage 2 mapping when marking dirty pages.
> +         */
> +        if (container->iommu_type == VFIO_TYPE1_NESTING_IOMMU) {
> +            return 0;
> +        }
> +
>          QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
>              if (MEMORY_REGION(giommu->iommu) == section->mr &&
>                  giommu->n.start == section->offset_within_region) {
> @@ -1312,6 +1336,7 @@ static const MemoryListener vfio_memory_listener = {
>  static MemoryListener vfio_memory_prereg_listener = {
>      .region_add = vfio_prereg_listener_region_add,
>      .region_del = vfio_prereg_listener_region_del,
> +    .log_sync = vfio_prereg_listener_log_sync,
>  };
>  
>  static void vfio_listener_release(VFIOContainer *container)
> 
Thanks

Eric