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>
diff --git a/dma-helpers.c b/dma-helpers.c
index f08cdb5..df0a421 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -204,3 +204,34 @@
{
return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque, true);
}
+
+
+static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg, bool to_dev)
+{
+ uint64_t resid;
+ int sg_cur_index;
+
+ resid = sg->size;
+ sg_cur_index = 0;
+ len = MIN(len, resid);
+ while (len > 0) {
+ ScatterGatherEntry entry = sg->sg[sg_cur_index++];
+ int32_t xfer = MIN(len, entry.len);
+ cpu_physical_memory_rw(entry.base, ptr, xfer, !to_dev);
+ ptr += xfer;
+ len -= xfer;
+ resid -= xfer;
+ }
+
+ return resid;
+}
+
+uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
+{
+ return dma_buf_rw(ptr, len, sg, 0);
+}
+
+uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
+{
+ return dma_buf_rw(ptr, len, sg, 1);
+}
