Re: [PATCH kernel v8 03/31] vfio: powerpc/spapr: Check that IOMMU page is fully contained by system page

[David Gibson]

On Fri, Apr 10, 2015 at 04:30:45PM +1000, Alexey Kardashevskiy wrote:
> This checks that the TCE table page size is not bigger that the size of
> a page we just pinned and going to put its physical address to the table.
> 
> Otherwise the hardware gets unwanted access to physical memory between
> the end of the actual page and the end of the aligned up TCE page.
> 
> Since compound_order() and compound_head() work correctly on non-huge
> pages, there is no need for additional check whether the page is huge.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>

Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>

Only thing I'm not sure about is...

> +		if (!tce_page_is_contained(page, tbl->it_page_shift)) {
> +			ret = -EPERM;
> +			break;

.. whether EPERM is the right error code.

-- 
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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