Re: [PATCH] powerpc-powernv: added tce_get callback for powernv platform

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Tue, 2012-09-04 at 17:35 +1000, Alexey Kardashevskiy wrote:
> The upcoming VFIO support requires a way to know which
> entry in the TCE map is not empty in order to do cleanup
> at QEMU exit/crash. This patch adds such functionality
> to POWERNV platform code.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  arch/powerpc/platforms/powernv/pci.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
> index be3cfc5..61f8068 100644
> --- a/arch/powerpc/platforms/powernv/pci.c
> +++ b/arch/powerpc/platforms/powernv/pci.c
> @@ -447,6 +447,11 @@ static void pnv_tce_free(struct iommu_table *tbl, long index, long npages)
>  		pnv_tce_invalidate(tbl, tces, tcep - 1);
>  }
>  
> +static unsigned long pnv_tce_get(struct iommu_table *tbl, long index)
> +{
> +	return ((u64 *)tbl->it_base)[index - tbl->it_offset] & IOMMU_PAGE_MASK;
> +}

Why the masking here ?

Cheers,
Ben.

>  void pnv_pci_setup_iommu_table(struct iommu_table *tbl,
>  			       void *tce_mem, u64 tce_size,
>  			       u64 dma_offset)
> @@ -597,6 +602,7 @@ void __init pnv_pci_init(void)
>  	ppc_md.pci_dma_dev_setup = pnv_pci_dma_dev_setup;
>  	ppc_md.tce_build = pnv_tce_build;
>  	ppc_md.tce_free = pnv_tce_free;
> +	ppc_md.tce_get = pnv_tce_get;
>  	ppc_md.pci_probe_mode = pnv_pci_probe_mode;
>  	set_pci_dma_ops(&dma_iommu_ops);
>