| Message ID | 1483713911-2079-1-git-send-email-nikita.yoush@cogentembedded.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello! On 1/6/2017 5:45 PM, Nikita Yushchenko wrote: > It is possible that device is capable of 64-bit DMA addresses, and > device driver tries to set wide DMA mask, but bridge or bus used to > connect device to the system can't handle wide addresses. > > With swiotlb, memory above 4G still can be used by drivers for streaming > DMA, but *dev->mask and dev->dma_coherent_mask must still keep values > that hardware handles physically. > > This patch enforces that. Based on original version by > Arnd Bergmann <arnd@arndb.de>, extended with coherent mask hadnling. > > Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com> > CC: Arnd Bergmann <arnd@arndb.de> [...] > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index 290a84f..09c7900 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -352,6 +352,31 @@ static int __swiotlb_dma_supported(struct device *hwdev, u64 mask) > return 1; > } > > +static int __swiotlb_set_dma_mask(struct device *dev, u64 mask) > +{ > + /* device is not DMA capable */ > + if (!dev->dma_mask) > + return -EIO; > + > + /* mask is below swiotlb bounce buffer, so fail */ > + if (!swiotlb_dma_supported(dev, mask)) > + return -EIO; > + > + /* > + * because of the swiotlb, we can return success for > + * larger masks, but need to ensure that bounce buffers > + * are used above parent_dma_mask, so set that as > + * the effective mask. > + */ > + if (mask > dev->archdata.parent_dma_mask) > + mask = dev->archdata.parent_dma_mask; > + > + One empty line is enough... > + *dev->dma_mask = mask; > + > + return 0; > +} > + > static struct dma_map_ops swiotlb_dma_ops = { > .alloc = __dma_alloc, > .free = __dma_free, [...] > @@ -957,6 +997,18 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, > if (!dev->archdata.dma_ops) > dev->archdata.dma_ops = &swiotlb_dma_ops; > > + /* > + * we don't yet support buses that have a non-zero mapping. > + * Let's hope we won't need it > + */ > + WARN_ON(dma_base != 0); > + > + /* > + * Whatever the parent bus can set. A device must not set > + * a DMA mask larger than this. > + */ > + dev->archdata.parent_dma_mask = size; Not 'size - 1'? > + > dev->archdata.dma_coherent = coherent; > __iommu_setup_dma_ops(dev, dma_base, size, iommu); > } MBR, Sergei
>> + if (mask > dev->archdata.parent_dma_mask) >> + mask = dev->archdata.parent_dma_mask; >> + >> + > > One empty line is enough... Ok >> + /* >> + * Whatever the parent bus can set. A device must not set >> + * a DMA mask larger than this. >> + */ >> + dev->archdata.parent_dma_mask = size; > > Not 'size - 1'? Good question. Indeed of_dma_configure() calls arch_setup_dma_ops() with size, not mask. Which implies '-1' is needed here. Although better fix may be to change caller side - to make DMA_BIT_MASK(64) case cleaner. Will repost path. Nikita
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1117421..afb2c08 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -216,6 +216,9 @@ config NEED_DMA_MAP_STATE config NEED_SG_DMA_LENGTH def_bool y +config ARCH_HAS_DMA_SET_COHERENT_MASK + def_bool y + config SMP def_bool y diff --git a/arch/arm64/include/asm/device.h b/arch/arm64/include/asm/device.h index 243ef25..a57e7bb 100644 --- a/arch/arm64/include/asm/device.h +++ b/arch/arm64/include/asm/device.h @@ -22,6 +22,7 @@ struct dev_archdata { void *iommu; /* private IOMMU data */ #endif bool dma_coherent; + u64 parent_dma_mask; }; struct pdev_archdata { diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 290a84f..09c7900 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -352,6 +352,31 @@ static int __swiotlb_dma_supported(struct device *hwdev, u64 mask) return 1; } +static int __swiotlb_set_dma_mask(struct device *dev, u64 mask) +{ + /* device is not DMA capable */ + if (!dev->dma_mask) + return -EIO; + + /* mask is below swiotlb bounce buffer, so fail */ + if (!swiotlb_dma_supported(dev, mask)) + return -EIO; + + /* + * because of the swiotlb, we can return success for + * larger masks, but need to ensure that bounce buffers + * are used above parent_dma_mask, so set that as + * the effective mask. + */ + if (mask > dev->archdata.parent_dma_mask) + mask = dev->archdata.parent_dma_mask; + + + *dev->dma_mask = mask; + + return 0; +} + static struct dma_map_ops swiotlb_dma_ops = { .alloc = __dma_alloc, .free = __dma_free, @@ -367,8 +392,23 @@ static struct dma_map_ops swiotlb_dma_ops = { .sync_sg_for_device = __swiotlb_sync_sg_for_device, .dma_supported = __swiotlb_dma_supported, .mapping_error = swiotlb_dma_mapping_error, + .set_dma_mask = __swiotlb_set_dma_mask, }; +int dma_set_coherent_mask(struct device *dev, u64 mask) +{ + if (!dma_supported(dev, mask)) + return -EIO; + + if (get_dma_ops(dev) == &swiotlb_dma_ops && + mask > dev->archdata.parent_dma_mask) + mask = dev->archdata.parent_dma_mask; + + dev->coherent_dma_mask = mask; + return 0; +} +EXPORT_SYMBOL(dma_set_coherent_mask); + static int __init atomic_pool_init(void) { pgprot_t prot = __pgprot(PROT_NORMAL_NC); @@ -957,6 +997,18 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, if (!dev->archdata.dma_ops) dev->archdata.dma_ops = &swiotlb_dma_ops; + /* + * we don't yet support buses that have a non-zero mapping. + * Let's hope we won't need it + */ + WARN_ON(dma_base != 0); + + /* + * Whatever the parent bus can set. A device must not set + * a DMA mask larger than this. + */ + dev->archdata.parent_dma_mask = size; + dev->archdata.dma_coherent = coherent; __iommu_setup_dma_ops(dev, dma_base, size, iommu); }
It is possible that device is capable of 64-bit DMA addresses, and device driver tries to set wide DMA mask, but bridge or bus used to connect device to the system can't handle wide addresses. With swiotlb, memory above 4G still can be used by drivers for streaming DMA, but *dev->mask and dev->dma_coherent_mask must still keep values that hardware handles physically. This patch enforces that. Based on original version by Arnd Bergmann <arnd@arndb.de>, extended with coherent mask hadnling. Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com> CC: Arnd Bergmann <arnd@arndb.de> --- ... now with initially missed change in arch_setup_dma_ops() ... arch/arm64/Kconfig | 3 +++ arch/arm64/include/asm/device.h | 1 + arch/arm64/mm/dma-mapping.c | 52 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 56 insertions(+)