[PATCH v2] fix host-endianness bug

[Alexandra Diupina]

Add a function xlnx_dpdma_read_descriptor() that
combines reading the descriptor from desc_addr
by calling dma_memory_read() and swapping desc
fields from guest memory order to host memory order.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d3c6369a96 ("introduce xlnx-dpdma")
Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
---
v2:minor changes in xlnx_dpdma_read_descriptor()
 hw/dma/xlnx_dpdma.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/hw/dma/xlnx_dpdma.c b/hw/dma/xlnx_dpdma.c
index dd66be5265..62a0952377 100644
--- a/hw/dma/xlnx_dpdma.c
+++ b/hw/dma/xlnx_dpdma.c
@@ -614,6 +614,34 @@ static void xlnx_dpdma_register_types(void)
     type_register_static(&xlnx_dpdma_info);
 }
 
+static MemTxResult xlnx_dpdma_read_descriptor(XlnxDPDMAState *s,
+                                    uint64_t desc_addr, DPDMADescriptor *desc)
+{
+    if (dma_memory_read(&address_space_memory, desc_addr, &desc,
+                            sizeof(DPDMADescriptor), MEMTXATTRS_UNSPECIFIED))
+        return MEMTX_ERROR;
+
+    /* Convert from LE into host endianness.  */
+    desc->control = le32_to_cpu(desc->control);
+    desc->descriptor_id = le32_to_cpu(desc->descriptor_id);
+    desc->xfer_size = le32_to_cpu(desc->xfer_size);
+    desc->line_size_stride = le32_to_cpu(desc->line_size_stride);
+    desc->timestamp_lsb = le32_to_cpu(desc->timestamp_lsb);
+    desc->timestamp_msb = le32_to_cpu(desc->timestamp_msb);
+    desc->address_extension = le32_to_cpu(desc->address_extension);
+    desc->next_descriptor = le32_to_cpu(desc->next_descriptor);
+    desc->source_address = le32_to_cpu(desc->source_address);
+    desc->address_extension_23 = le32_to_cpu(desc->address_extension_23);
+    desc->address_extension_45 = le32_to_cpu(desc->address_extension_45);
+    desc->source_address2 = le32_to_cpu(desc->source_address2);
+    desc->source_address3 = le32_to_cpu(desc->source_address3);
+    desc->source_address4 = le32_to_cpu(desc->source_address4);
+    desc->source_address5 = le32_to_cpu(desc->source_address5);
+    desc->crc = le32_to_cpu(desc->crc);
+
+    return MEMTX_OK;
+}
+
 size_t xlnx_dpdma_start_operation(XlnxDPDMAState *s, uint8_t channel,
                                     bool one_desc)
 {
@@ -651,8 +679,7 @@ size_t xlnx_dpdma_start_operation(XlnxDPDMAState *s, 
uint8_t channel,
             desc_addr = xlnx_dpdma_descriptor_next_address(s, channel);
         }
 
-        if (dma_memory_read(&address_space_memory, desc_addr, &desc,
-                            sizeof(DPDMADescriptor), MEMTXATTRS_UNSPECIFIED)) {
+        if (xlnx_dpdma_read_descriptor(s, desc_addr, &desc)) {
             s->registers[DPDMA_EISR] |= ((1 << 1) << channel);
             xlnx_dpdma_update_irq(s);
             s->operation_finished[channel] = true;
-- 
2.30.2