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powerpc/powernv: Add iommu DMA bypass support for IODA2

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This patch adds the support for to create a direct iommu "bypass"
window on IODA2 bridges (such as Power8) allowing to bypass iommu
page translation completely for 64-bit DMA capable devices, thus
significantly improving DMA performances.

Additionally, this adds a hook to the struct iommu_table so that
the IOMMU API / VFIO can disable the bypass when external ownership
is requested, since in that case, the device will be used by an
environment such as userspace or a KVM guest which must not be
allowed to bypass translations.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt
2014-02-11 11:32:38 +11:00
parent ea961a828f
commit cd15b04844
9 changed files with 137 additions and 4 deletions
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10
arch/powerpc/kernel/dma.c
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@@ -191,12 +191,10 @@ EXPORT_SYMBOL(dma_direct_ops);
#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
int dma_set_mask(struct device *dev, u64 dma_mask)
int __dma_set_mask(struct device *dev, u64 dma_mask)
{
struct dma_map_ops *dma_ops = get_dma_ops(dev);
if (ppc_md.dma_set_mask)
return ppc_md.dma_set_mask(dev, dma_mask);
if ((dma_ops != NULL) && (dma_ops->set_dma_mask != NULL))
return dma_ops->set_dma_mask(dev, dma_mask);
if (!dev->dma_mask || !dma_supported(dev, dma_mask))
@@ -204,6 +202,12 @@ int dma_set_mask(struct device *dev, u64 dma_mask)
*dev->dma_mask = dma_mask;
return 0;
}
int dma_set_mask(struct device *dev, u64 dma_mask)
{
if (ppc_md.dma_set_mask)
return ppc_md.dma_set_mask(dev, dma_mask);
return __dma_set_mask(dev, dma_mask);
}
EXPORT_SYMBOL(dma_set_mask);
u64 dma_get_required_mask(struct device *dev)