> +{
> + struct vfio_pci_dma_buf *priv = dmabuf->priv;
> + int rc;
> +
> + rc = pci_p2pdma_distance_many(priv->vdev->pdev, &attachment->dev, 1,
> + true);
This should just use pci_p2pdma_distance.
> + /*
> + * Since the memory being mapped is a device memory it could never be in
> + * CPU caches.
> + */
DMA_ATTR_SKIP_CPU_SYNC doesn't even apply to dma_map_resource, not sure
where this wisdom comes from.
> + dma_addr = dma_map_resource(
> + attachment->dev,
> + pci_resource_start(priv->vdev->pdev, priv->index) +
> + priv->offset,
> + priv->dmabuf->size, dir, DMA_ATTR_SKIP_CPU_SYNC);
This is not how P2P addresses are mapped. You need to use
dma_map_sgtable and have the proper pgmap for it.
The above is just a badly implemented version of the dma-direct
PCI_P2PDMA_MAP_BUS_ADDR case, ignoring mappings through the host
bridge or dma-map-ops interactions.
