[PATCH] iommu/io-pgtable-arm: Make allocations NUMA-aware

[Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>]

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.murphy-5wv7dgnIgG8@public.gmane.org>
---
 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);
 	if (!(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) {
 		dma = dma_map_single(dev, pages, size, DMA_TO_DEVICE);
 		if (dma_mapping_error(dev, dma))
@@ -256,7 +260,7 @@ static void *__arm_lpae_alloc_pages(size_t size, gfp_t gfp,
 	dev_err(dev, "Cannot accommodate DMA translation for IOMMU page tables\n");
 	dma_unmap_single(dev, dma, size, DMA_TO_DEVICE);
 out_free:
-	free_pages_exact(pages, size);
+	__free_pages(p, order);
 	return NULL;
 }
 
@@ -266,7 +270,7 @@ static void __arm_lpae_free_pages(void *pages, size_t size,
 	if (!(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA))
 		dma_unmap_single(cfg->iommu_dev, __arm_lpae_dma_addr(pages),
 				 size, DMA_TO_DEVICE);
-	free_pages_exact(pages, size);
+	free_pages((unsigned long)pages, get_order(size));
 }
 
 static void __arm_lpae_sync_pte(arm_lpae_iopte *ptep,
-- 
2.17.0.dirty