Re: [PATCH V1 7/9] iommufd: file mappings for mdev

[Steven Sistare <steven.sistare@oracle.com>]

Hi Jason, any comments or RB on this before I submit V2? - steve

On 9/14/2024 9:05 AM, Steve Sistare wrote:
> Support file mappings for mediated devices, aka mdevs.  Access is initiated
> by the vfio_pin_pages and vfio_dma_rw kernel interfaces.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>   drivers/iommu/iommufd/pages.c | 22 +++++++++++++++-------
>   1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c
> index 8c8d0ff..4cb532e 100644
> --- a/drivers/iommu/iommufd/pages.c
> +++ b/drivers/iommu/iommufd/pages.c
> @@ -1706,11 +1706,11 @@ static int iopt_pages_fill_from_domain(struct iopt_pages *pages,
>   	return 0;
>   }
>   
> -static int iopt_pages_fill_from_mm(struct iopt_pages *pages,
> -				   struct pfn_reader_user *user,
> -				   unsigned long start_index,
> -				   unsigned long last_index,
> -				   struct page **out_pages)
> +static int iopt_pages_fill(struct iopt_pages *pages,
> +			   struct pfn_reader_user *user,
> +			   unsigned long start_index,
> +			   unsigned long last_index,
> +			   struct page **out_pages)
>   {
>   	unsigned long cur_index = start_index;
>   	int rc;
> @@ -1784,8 +1784,8 @@ int iopt_pages_fill_xarray(struct iopt_pages *pages, unsigned long start_index,
>   
>   		/* hole */
>   		cur_pages = out_pages + (span.start_hole - start_index);
> -		rc = iopt_pages_fill_from_mm(pages, &user, span.start_hole,
> -					     span.last_hole, cur_pages);
> +		rc = iopt_pages_fill(pages, &user, span.start_hole,
> +				     span.last_hole, cur_pages);
>   		if (rc)
>   			goto out_clean_xa;
>   		rc = pages_to_xarray(&pages->pinned_pfns, span.start_hole,
> @@ -1865,6 +1865,9 @@ static int iopt_pages_rw_page(struct iopt_pages *pages, unsigned long index,
>   	struct page *page = NULL;
>   	int rc;
>   
> +	if (WARN_ON(pages->type != IOPT_ADDRESS_USER))
> +		return -EINVAL;
> +
>   	if (!mmget_not_zero(pages->source_mm))
>   		return iopt_pages_rw_slow(pages, index, index, offset, data,
>   					  length, flags);
> @@ -1920,6 +1923,11 @@ int iopt_pages_rw_access(struct iopt_pages *pages, unsigned long start_byte,
>   	if ((flags & IOMMUFD_ACCESS_RW_WRITE) && !pages->writable)
>   		return -EPERM;
>   
> +	if (pages->type == IOPT_ADDRESS_FILE)
> +		return iopt_pages_rw_slow(pages, start_index, last_index,
> +					  start_byte % PAGE_SIZE, data, length,
> +					  flags);
> +
>   	if (!(flags & IOMMUFD_ACCESS_RW_KTHREAD) && change_mm) {
>   		if (start_index == last_index)
>   			return iopt_pages_rw_page(pages, start_index,