Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
virtio-rng: fix DMA alignment for data buffer
The data buffer in struct virtrng_info is used for DMA_FROM_DEVICE via
virtqueue_add_inbuf() and shares cachelines with the adjacent
CPU-written fields (data_avail, data_idx).
The device writing to the DMA buffer and the CPU writing to adjacent
fields could corrupt each other's data on non-cache-coherent platforms.
Add __dma_from_device_group_begin()/end() annotations to place these
in distinct cache lines.
Message-ID: <157a63b6324d1f1307ddd4faa3b62a8b90a79423.1767601130.git.mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
+3
+3
drivers/char/hw_random/virtio-rng.c
+3
drivers/char/hw_random/virtio-rng.c
···
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#include <linux/spinlock.h>
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#include <linux/virtio.h>
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#include <linux/virtio_rng.h>
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+
#include <linux/dma-mapping.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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···
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unsigned int data_avail;
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unsigned int data_idx;
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/* minimal size returned by rng_buffer_size() */
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__dma_from_device_group_begin();
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#if SMP_CACHE_BYTES < 32
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u8 data[32];
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#else
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u8 data[SMP_CACHE_BYTES];
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#endif
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__dma_from_device_group_end();
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};
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static void random_recv_done(struct virtqueue *vq)