On 20/09/18 19:52, Christoph Hellwig wrote:
We need to take the DMA offset and encryption bit into account when selecting a zone. User the opportunity to factor out the zone selection into a helper for reuse.Signed-off-by: Christoph Hellwig <h...@lst.de> --- kernel/dma/direct.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 81b73a5bba54..3c404e33d946 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -68,6 +68,22 @@ u64 dma_direct_get_required_mask(struct device *dev) return (1ULL << (fls64(max_dma) - 1)) * 2 - 1; }+static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,+ u64 *phys_mask) +{ + if (force_dma_unencrypted()) + *phys_mask = __dma_to_phys(dev, dma_mask); + else + *phys_mask = dma_to_phys(dev, dma_mask);
Maybe make phys_to_dma_direct() take u64 instead of phys_addr_t so we can reuse it here?
+ /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */ + if (*phys_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)) + return GFP_DMA;
If we don't have ZONE_DMA it would in theory be a tiny bit better to fall back to GFP_DMA32 instead of returning 0 here, but I'm not sure it's worth the bother.
+ if (*phys_mask <= DMA_BIT_MASK(32)) + return GFP_DMA32; + return 0; +} + static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) { return phys_to_dma_direct(dev, phys) + size - 1 <= @@ -80,17 +96,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; int page_order = get_order(size); struct page *page = NULL; + u64 phys_mask; void *ret;/* we always manually zero the memory once we are done: */gfp &= ~__GFP_ZERO; - - /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */ - if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS)) - gfp |= GFP_DMA; - if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) - gfp |= GFP_DMA32; - + gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask, + &phys_mask); again: /* CMA can be used only in the context which permits sleeping */ if (gfpflags_allow_blocking(gfp)) { @@ -109,15 +121,14 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, page = NULL;if (IS_ENABLED(CONFIG_ZONE_DMA32) &&- dev->coherent_dma_mask < DMA_BIT_MASK(64) && + phys_mask < DMA_BIT_MASK(64) && !(gfp & (GFP_DMA32 | GFP_DMA))) { gfp |= GFP_DMA32; goto again;
Ah right, in that situation we should probably end up here anyway, so that's good enough - definitely not worth any more #ifdeffery above. Nits aside,
Reviewed-by: Robin Murphy <robin.mur...@arm.com>
}if (IS_ENABLED(CONFIG_ZONE_DMA) &&- dev->coherent_dma_mask < DMA_BIT_MASK(32) && - !(gfp & GFP_DMA)) { + phys_mask < DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) { gfp = (gfp & ~GFP_DMA32) | GFP_DMA; goto again; }
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