On non-cache-coherent platforms, when a structure contains a buffer used for DMA alongside fields that the CPU writes to, cacheline sharing can cause data corruption.
The evts array is used for DMA_FROM_DEVICE operations via virtqueue_add_inbuf(). The adjacent lock and ready fields are written by the CPU during normal operation. If these share cachelines with evts, CPU writes can corrupt DMA data. Add __dma_from_device_aligned_begin/end annotations to ensure evts is isolated in its own cachelines. Signed-off-by: Michael S. Tsirkin <[email protected]> --- drivers/virtio/virtio_input.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c index d0728285b6ce..774494754a99 100644 --- a/drivers/virtio/virtio_input.c +++ b/drivers/virtio/virtio_input.c @@ -4,6 +4,7 @@ #include <linux/virtio_config.h> #include <linux/input.h> #include <linux/slab.h> +#include <linux/dma-mapping.h> #include <uapi/linux/virtio_ids.h> #include <uapi/linux/virtio_input.h> @@ -16,7 +17,9 @@ struct virtio_input { char serial[64]; char phys[64]; struct virtqueue *evt, *sts; + __dma_from_device_aligned_begin struct virtio_input_event evts[64]; + __dma_from_device_aligned_end spinlock_t lock; bool ready; }; -- MST
