RE: [PATCH v2 10/10] vfio: Do not allow !ops->dma_unmap in vfio_pin/unpin_pages()

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Wednesday, February 8, 2023 5:18 AM
> 
> A driver that doesn't implement ops->dma_unmap shouldn't be allowed to
> do
> vfio_pin/unpin_pages(), though it can use vfio_dma_rw() to access an iova
> range. Deny !ops->dma_unmap cases in vfio_pin/unpin_pages().
> 
> Suggested-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> ---
>  drivers/vfio/vfio_main.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 8559c3dfb335..c7f3251ad6e5 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -1543,6 +1543,8 @@ int vfio_pin_pages(struct vfio_device *device,
> dma_addr_t iova,
> 
>  		if (iova > ULONG_MAX)
>  			return -EINVAL;
> +		if (!device->ops->dma_unmap)
> +			return -EINVAL;
>  		/*
>  		 * VFIO ignores the sub page offset, npages is from the start
> of
>  		 * a PAGE_SIZE chunk of IOVA. The caller is expected to
> recover
> @@ -1580,6 +1582,8 @@ void vfio_unpin_pages(struct vfio_device *device,
> dma_addr_t iova, int npage)
>  	if (device->iommufd_access) {
>  		if (WARN_ON(iova > ULONG_MAX))
>  			return;
> +		if (!device->ops->dma_unmap)
> +			return;

IMHO this restriction applies to both iommufd and legacy container.