xlnx_dpdma: fix descriptor endianness bug

Add xlnx_dpdma_read_descriptor() and
xlnx_dpdma_write_descriptor() functions.
xlnx_dpdma_read_descriptor() combines reading a
descriptor from desc_addr by calling dma_memory_read()
and swapping the desc fields from guest memory order
to host memory order. xlnx_dpdma_write_descriptor()
performs similar actions when writing a descriptor.

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

Fixes: d3c6369a96 ("introduce xlnx-dpdma")
Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
[PMM: tweaked indent, dropped behaviour change for write-failure case]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 64 insertions, 4 deletions

diff --git a/hw/dma/xlnx_dpdma.c b/hw/dma/xlnx_dpdma.c
index 530717d..dde4aec 100644
--- a/hw/dma/xlnx_dpdma.c
+++ b/hw/dma/xlnx_dpdma.c
@@ -614,6 +614,65 @@ 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)
+{
+    MemTxResult res = dma_memory_read(&address_space_memory, desc_addr,
+                                      &desc, sizeof(DPDMADescriptor),
+                                      MEMTXATTRS_UNSPECIFIED);
+    if (res) {
+        return res;
+    }
+
+    /* 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 res;
+}
+
+static MemTxResult xlnx_dpdma_write_descriptor(uint64_t desc_addr,
+                                               DPDMADescriptor *desc)
+{
+    DPDMADescriptor tmp_desc = *desc;
+
+    /* Convert from host endianness into LE.  */
+    tmp_desc.control = cpu_to_le32(tmp_desc.control);
+    tmp_desc.descriptor_id = cpu_to_le32(tmp_desc.descriptor_id);
+    tmp_desc.xfer_size = cpu_to_le32(tmp_desc.xfer_size);
+    tmp_desc.line_size_stride = cpu_to_le32(tmp_desc.line_size_stride);
+    tmp_desc.timestamp_lsb = cpu_to_le32(tmp_desc.timestamp_lsb);
+    tmp_desc.timestamp_msb = cpu_to_le32(tmp_desc.timestamp_msb);
+    tmp_desc.address_extension = cpu_to_le32(tmp_desc.address_extension);
+    tmp_desc.next_descriptor = cpu_to_le32(tmp_desc.next_descriptor);
+    tmp_desc.source_address = cpu_to_le32(tmp_desc.source_address);
+    tmp_desc.address_extension_23 = cpu_to_le32(tmp_desc.address_extension_23);
+    tmp_desc.address_extension_45 = cpu_to_le32(tmp_desc.address_extension_45);
+    tmp_desc.source_address2 = cpu_to_le32(tmp_desc.source_address2);
+    tmp_desc.source_address3 = cpu_to_le32(tmp_desc.source_address3);
+    tmp_desc.source_address4 = cpu_to_le32(tmp_desc.source_address4);
+    tmp_desc.source_address5 = cpu_to_le32(tmp_desc.source_address5);
+    tmp_desc.crc = cpu_to_le32(tmp_desc.crc);
+
+    return dma_memory_write(&address_space_memory, desc_addr, &tmp_desc,
+                            sizeof(DPDMADescriptor), MEMTXATTRS_UNSPECIFIED);
+}
+
 size_t xlnx_dpdma_start_operation(XlnxDPDMAState *s, uint8_t channel,
                                     bool one_desc)
 {
@@ -651,8 +710,7 @@ 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;
@@ -755,8 +813,10 @@ size_t xlnx_dpdma_start_operation(XlnxDPDMAState *s, uint8_t channel,
             /* The descriptor need to be updated when it's completed. */
             DPRINTF("update the descriptor with the done flag set.\n");
             xlnx_dpdma_desc_set_done(&desc);
-            dma_memory_write(&address_space_memory, desc_addr, &desc,
-                             sizeof(DPDMADescriptor), MEMTXATTRS_UNSPECIFIED);
+            if (xlnx_dpdma_write_descriptor(desc_addr, &desc)) {
+                DPRINTF("Can't write the descriptor.\n");
+                /* TODO: check hardware behaviour for memory write failure */
+            }
         }
 
         if (xlnx_dpdma_desc_completion_interrupt(&desc)) {