iommu/io-pgtable-arm: Make allocations NUMA-aware

We would generally expect pagetables to be read by the IOMMU more than written by the CPU, so in NUMA systems it makes sense to locate them close to the former and avoid cross-node pagetable walks if at all possible. As it turns out, 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.

Acked-by Will Deacon <[email protected]>

Signed-off-by Robin Murphy <[email protected]>

---

v2: Retain equivalent highmem check

 drivers/iommu/io-pgtable-arm.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

drivers/iommu/io-pgtable-arm.c +9 -4

index 39c2a056da21..5194755bba29 100644
@@ -231,12 +231,17 @@ 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)
+	VM_BUG_ON((gfp & __GFP_HIGHMEM));
+	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 +261,7 @@ 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 +271,7 @@ 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,

Signature · 1 line

2.17.0.dirty

Acked-by Will Deacon <[email protected]>

Signed-off-by Robin Murphy <[email protected]>

---

v2: Retain equivalent highmem check

 drivers/iommu/io-pgtable-arm.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)