On Mon, May 21, 2018 at 07:12:40PM +0100, Robin Murphy wrote:
> We would generally expect pagetables to be read by the IOMMU more than
> written by the CPU, so in NUMA systems it would be preferable to avoid
> the IOMMU making cross-node pagetable walks if possible. We already have
> a handle on the IOMMU device for the sake of coherency management, so
> it's trivial to grab the appropriate NUMA node when allocating new
> pagetable pages.
>
> Note that we drop the semantics of alloc_pages_exact(), but that's fine
> since they have never been necessary: the only time we're allocating
> more than one page is for stage 2 top-level concatenation, but since
> that is based on the number of IPA bits, the size is always some exact
> power of two anyway.
>
> Signed-off-by: Robin Murphy <robin.mur...@arm.com>
> ---
> drivers/iommu/io-pgtable-arm.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 39c2a056da21..e80ca386c5b4 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -231,12 +231,16 @@ static void *__arm_lpae_alloc_pages(size_t size, gfp_t
> gfp,
> struct io_pgtable_cfg *cfg)
> {
> struct device *dev = cfg->iommu_dev;
> + int order = get_order(size);
> + struct page *p;
> dma_addr_t dma;
> - void *pages = alloc_pages_exact(size, gfp | __GFP_ZERO);
> + void *pages;
>
> - if (!pages)
> + p = alloc_pages_node(dev_to_node(dev), gfp | __GFP_ZERO, order);
> + if (!p)
> return NULL;
>
> + pages = page_address(p);
Might be worth checking/masking out __GFP_HIGHMEM if we see it, since we
could theoretically run into trouble if we got back a highmem mapping here
and we're losing the check in __get_free_pages afaict.
Other than than, looks good:
Acked-by: Will Deacon <will.dea...@arm.com>
Will
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