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dma-helpers: add dma_buf_read and dma_buf_write
These helpers do a full transfer from an in-memory buffer to target memory, with support for scatter/gather lists. It will be used to store the reply of an emulated command into a QEMUSGList provided by the adapter. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -204,3 +204,34 @@ BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
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{
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return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque, true);
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}
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static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg, bool to_dev)
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{
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uint64_t resid;
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int sg_cur_index;
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resid = sg->size;
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sg_cur_index = 0;
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len = MIN(len, resid);
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while (len > 0) {
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ScatterGatherEntry entry = sg->sg[sg_cur_index++];
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int32_t xfer = MIN(len, entry.len);
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cpu_physical_memory_rw(entry.base, ptr, xfer, !to_dev);
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ptr += xfer;
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len -= xfer;
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resid -= xfer;
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}
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return resid;
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}
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uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
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{
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return dma_buf_rw(ptr, len, sg, 0);
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}
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uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
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{
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return dma_buf_rw(ptr, len, sg, 1);
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}
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3
dma.h
3
dma.h
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@ -58,4 +58,7 @@ BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
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BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
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QEMUSGList *sg, uint64_t sector,
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BlockDriverCompletionFunc *cb, void *opaque);
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uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg);
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uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg);
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#endif
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