[PATCH v2 01/15] dma-mapping: add __dma_from_device_group_begin()/end()
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2026-01-05 08:23:01
Also in:
kvm, linux-crypto, linux-doc, linux-iommu, linux-scsi, lkml, virtualization
Subsystem:
dma mapping helpers, the rest · Maintainers:
Marek Szyprowski, Linus Torvalds
When a structure contains a buffer that DMA writes to alongside fields
that the CPU writes to, cache line sharing between the DMA buffer and
CPU-written fields can cause data corruption on non-cache-coherent
platforms.
Add __dma_from_device_group_begin()/end() annotations to ensure proper
alignment to prevent this:
struct my_device {
spinlock_t lock1;
__dma_from_device_group_begin();
char dma_buffer1[16];
char dma_buffer2[16];
__dma_from_device_group_end();
spinlock_t lock2;
};
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/linux/dma-mapping.h | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index aa36a0d1d9df..29ad2ce700f0 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h@@ -7,6 +7,7 @@ #include <linux/dma-direction.h> #include <linux/scatterlist.h> #include <linux/bug.h> +#include <linux/cache.h> /** * List of possible attributes associated with a DMA mapping. The semantics
@@ -703,6 +704,18 @@ static inline int dma_get_cache_alignment(void) } #endif +#ifdef ARCH_HAS_DMA_MINALIGN +#define ____dma_from_device_aligned __aligned(ARCH_DMA_MINALIGN) +#else +#define ____dma_from_device_aligned +#endif +/* Mark start of DMA buffer */ +#define __dma_from_device_group_begin(GROUP) \ + __cacheline_group_begin(GROUP) ____dma_from_device_aligned +/* Mark end of DMA buffer */ +#define __dma_from_device_group_end(GROUP) \ + __cacheline_group_end(GROUP) ____dma_from_device_aligned + static inline void *dmam_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp) {
--
MST