Re: [RFC PATCH kernel 1/5] vfio/spapr_tce: Simplify page contained test

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Jun 07, 2018 at 06:44:16PM +1000, Alexey Kardashevskiy wrote:
> The test function takes a page struct pointer which is not used by
> either of two callers in any other way, make it simple and just pass
> a physical address there.
> 
> This should cause no behavioral change now but later we may start
> supporting host addresses for memory devices which are not backed
> with page structs.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  drivers/vfio/vfio_iommu_spapr_tce.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 759a5bd..2c4a048 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -249,8 +249,9 @@ static void tce_iommu_userspace_view_free(struct iommu_table *tbl,
>  	decrement_locked_vm(mm, cb >> PAGE_SHIFT);
>  }
>  
> -static bool tce_page_is_contained(struct page *page, unsigned page_shift)
> +static bool tce_page_is_contained(unsigned long hpa, unsigned page_shift)
>  {
> +	struct page *page = pfn_to_page(hpa >> PAGE_SHIFT);
>  	/*
>  	 * Check that the TCE table granularity is not bigger than the size of
>  	 * a page we just found. Otherwise the hardware can get access to
> @@ -549,7 +550,6 @@ static long tce_iommu_build(struct tce_container *container,
>  		enum dma_data_direction direction)
>  {
>  	long i, ret = 0;
> -	struct page *page;
>  	unsigned long hpa;
>  	enum dma_data_direction dirtmp;
>  
> @@ -560,8 +560,7 @@ static long tce_iommu_build(struct tce_container *container,
>  		if (ret)
>  			break;
>  
> -		page = pfn_to_page(hpa >> PAGE_SHIFT);
> -		if (!tce_page_is_contained(page, tbl->it_page_shift)) {
> +		if (!tce_page_is_contained(hpa, tbl->it_page_shift)) {
>  			ret = -EPERM;
>  			break;
>  		}
> @@ -595,7 +594,6 @@ static long tce_iommu_build_v2(struct tce_container *container,
>  		enum dma_data_direction direction)
>  {
>  	long i, ret = 0;
> -	struct page *page;
>  	unsigned long hpa;
>  	enum dma_data_direction dirtmp;
>  
> @@ -615,8 +613,7 @@ static long tce_iommu_build_v2(struct tce_container *container,
>  		if (ret)
>  			break;
>  
> -		page = pfn_to_page(hpa >> PAGE_SHIFT);
> -		if (!tce_page_is_contained(page, tbl->it_page_shift)) {
> +		if (!tce_page_is_contained(hpa, tbl->it_page_shift)) {
>  			ret = -EPERM;
>  			break;
>  		}

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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