Re: [PATCH v2] iommu/io-pgtable-arm: Make allocations NUMA-aware

[Joerg Roedel]

On Tue, May 22, 2018 at 12:50:09PM +0100, Robin Murphy wrote:
> Acked-by: Will Deacon 
> Signed-off-by: Robin Murphy 
> ---
> 
> v2: Retain equivalent highmem check
> 
>  drivers/iommu/io-pgtable-arm.c | 13 +
>  1 file changed, 9 insertions(+), 4 deletions(-)

Applied, thanks.

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Re: [PATCH v2] iommu/io-pgtable-arm: Make allocations NUMA-aware

[Will Deacon]

On Tue, May 22, 2018 at 12:50:09PM +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 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 
> Signed-off-by: Robin Murphy 
> ---
> 
> v2: Retain equivalent highmem check
> 
>  drivers/iommu/io-pgtable-arm.c | 13 +
>  1 file changed, 9 insertions(+), 4 deletions(-)

Thanks, Robin.

Joerg -- please you can pick this up for 4.18? I don't have any other SMMU
patches pending, so it doesn't seem worth putting together a pull request
just for this.

Cheers,

Will

> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 39c2a056da21..5194755bba29 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -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,
> -- 
> 2.17.0.dirty
> 
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[PATCH v2] iommu/io-pgtable-arm: Make allocations NUMA-aware

[Robin Murphy]

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 
Signed-off-by: Robin Murphy 
---

v2: Retain equivalent highmem check

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

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 39c2a056da21..5194755bba29 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -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,
-- 
2.17.0.dirty

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