Re: [dpdk-dev] [PATCH v5 1/1] vfio: modify spapr iommu support to use static window sizing

[Thomas Monjalon <thomas@monjalon.net>]

03/11/2020 23:05, David Christensen:
> The SPAPR IOMMU requires that a DMA window size be defined before memory
> can be mapped for DMA. Current code dynamically modifies the DMA window
> size in response to every new memory allocation which is potentially
> dangerous because all existing mappings need to be unmapped/remapped in
> order to resize the DMA window, leaving hardware holding IOVA addresses
> that are temporarily unmapped.  The new SPAPR code statically assigns
> the DMA window size on first use, using the largest physical memory
> memory address when IOVA=PA and the highest existing memseg virtual
> address when IOVA=VA.
> 
> Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
> Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
> ---
> -#ifdef VFIO_IOMMU_SPAPR_INFO_DDW
> -		/* try possible page_shift and levels for workaround */
> +		/* if at first we don't succeed, try more levels */
>  		uint32_t levels;
>  
> -		for (levels = create->levels + 1;
> +		for (levels = create.levels + 1;
>  			ret && levels <= info.ddw.levels; levels++) {

There is a compilation failure with ppc64le-power8-linux-gcc:
error: ‘struct vfio_iommu_spapr_tce_info’ has no member named ‘ddw’