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iommu/dma: Implement PCI allocation optimisation

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Whilst PCI devices may have 64-bit DMA masks, they still benefit from
using 32-bit addresses wherever possible in order to avoid DAC (PCI) or
longer address packets (PCIe), which may incur a performance overhead.
Implement the same optimisation as other allocators by trying to get a
32-bit address first, only falling back to the full mask if that fails.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Robin Murphy 2017-01-16 13:24:55 +00:00 committed by Joerg Roedel
parent f51d7bb79c
commit 122fac030e
1 changed files with 15 additions and 6 deletions
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21
drivers/iommu/dma-iommu.c
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@ -287,19 +287,28 @@ int dma_info_to_prot(enum dma_data_direction dir, bool coherent,
}
static struct iova *__alloc_iova(struct iommu_domain *domain, size_t size,
dma_addr_t dma_limit)
dma_addr_t dma_limit, struct device *dev)
{
struct iova_domain *iovad = cookie_iovad(domain);
unsigned long shift = iova_shift(iovad);
unsigned long length = iova_align(iovad, size) >> shift;
struct iova *iova = NULL;
if (domain->geometry.force_aperture)
dma_limit = min(dma_limit, domain->geometry.aperture_end);
/* Try to get PCI devices a SAC address */
if (dma_limit > DMA_BIT_MASK(32) && dev_is_pci(dev))
iova = alloc_iova(iovad, length, DMA_BIT_MASK(32) >> shift,
true);
/*
* Enforce size-alignment to be safe - there could perhaps be an
* attribute to control this per-device, or at least per-domain...
*/
return alloc_iova(iovad, length, dma_limit >> shift, true);
if (!iova)
iova = alloc_iova(iovad, length, dma_limit >> shift, true);
return iova;
}
/* The IOVA allocator knows what we mapped, so just unmap whatever that was */
@ -452,7 +461,7 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
if (!pages)
return NULL;
iova = __alloc_iova(domain, size, dev->coherent_dma_mask);
iova = __alloc_iova(domain, size, dev->coherent_dma_mask, dev);
if (!iova)
goto out_free_pages;
@ -523,7 +532,7 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
struct iova_domain *iovad = cookie_iovad(domain);
size_t iova_off = iova_offset(iovad, phys);
size_t len = iova_align(iovad, size + iova_off);
struct iova *iova = __alloc_iova(domain, len, dma_get_mask(dev));
struct iova *iova = __alloc_iova(domain, len, dma_get_mask(dev), dev);
if (!iova)
return DMA_ERROR_CODE;
@ -681,7 +690,7 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
prev = s;
}
iova = __alloc_iova(domain, iova_len, dma_get_mask(dev));
iova = __alloc_iova(domain, iova_len, dma_get_mask(dev), dev);
if (!iova)
goto out_restore_sg;
@ -761,7 +770,7 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
msi_page->phys = msi_addr;
if (iovad) {
iova = __alloc_iova(domain, size, dma_get_mask(dev));
iova = __alloc_iova(domain, size, dma_get_mask(dev), dev);
if (!iova)
goto out_free_page;
msi_page->iova = iova_dma_addr(iovad, iova);