Merge tag 'dma-mapping-4.20-3' of git://git.infradead.org/users/hch/dma-mapping

torvalds · torvalds · commit d6d460b89378 · 2018-11-25T09:24:40.000-08:00
Pull dma-mapping fixes from Christoph Hellwig:
 "Two dma-direct / swiotlb regressions fixes:

   - zero is a valid physical address on some arm boards, we can't use
     it as the error value

   - don't try to cache flush the error return value (no matter what it
     is)"

* tag 'dma-mapping-4.20-3' of git://git.infradead.org/users/hch/dma-mapping:
  swiotlb: Skip cache maintenance on map error
  dma-direct: Make DIRECT_MAPPING_ERROR viable for SWIOTLB
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
@@ -5,7 +5,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/mem_encrypt.h>
 
-#define DIRECT_MAPPING_ERROR		0
+#define DIRECT_MAPPING_ERROR		(~(dma_addr_t)0)
 
 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
 #include <asm/dma-direct.h>
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
@@ -679,7 +679,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 	}
 
 	if (!dev_is_dma_coherent(dev) &&
-	    (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
+	    (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0 &&
+	    dev_addr != DIRECT_MAPPING_ERROR)
 		arch_sync_dma_for_device(dev, phys, size, dir);
 
 	return dev_addr;

Original file line number	Diff line number	Diff line change
`@@ -679,7 +679,8 @@ dma_addr_t swiotlb_map_page(struct device dev, struct page page,`
`679`	`679`	`}`
`680`	`680`
`681`	`681`	`if (!dev_is_dma_coherent(dev) &&`
`682`		`- (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)`
	`682`	`+ (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0 &&`
	`683`	`+ dev_addr != DIRECT_MAPPING_ERROR)`
`683`	`684`	`arch_sync_dma_for_device(dev, phys, size, dir);`
`684`	`685`
`685`	`686`	`return dev_addr;`