hw/dma/xilinx_axidma: Check DMASR.HALTED to prevent infinite loop.

When we receive a packet from the xilinx_axienet and then try to s2mem
through the xilinx_axidma, if the descriptor ring buffer is full in the
xilinx axidma driver, we’ll assert the DMASR.HALTED in the
function : stream_process_s2mem and return 0. In the end, we’ll be stuck in
an infinite loop in axienet_eth_rx_notify.

This patch checks the DMASR.HALTED state when we try to push data
from xilinx axi-enet to xilinx axi-dma. When the DMASR.HALTED is asserted,
we will not keep pushing the data and then prevent the infinte loop.

Signed-off-by: Tommy Wu <tommy.wu@sifive.com>
Reviewed-by: Edgar E. Iglesias <edgar@zeroasic.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Message-id: 20230519062137.1251741-1-tommy.wu@sifive.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/dma/xilinx_axidma.c

@@ -168,6 +168,11 @@ static inline int stream_idle(struct Stream *s)
     return !!(s->regs[R_DMASR] & DMASR_IDLE);
 }
 
+static inline int stream_halted(struct Stream *s)
+{
+    return !!(s->regs[R_DMASR] & DMASR_HALTED);
+}
+
 static void stream_reset(struct Stream *s)
 {
     s->regs[R_DMASR] = DMASR_HALTED;  /* starts up halted.  */
@@ -269,7 +274,7 @@ static void stream_process_mem2s(struct Stream *s, StreamSink *tx_data_dev,
     uint64_t addr;
     bool eop;
 
-    if (!stream_running(s) || stream_idle(s)) {
+    if (!stream_running(s) || stream_idle(s) || stream_halted(s)) {
         return;
     }
 
@@ -326,7 +331,7 @@ static size_t stream_process_s2mem(struct Stream *s, unsigned char *buf,
     unsigned int rxlen;
     size_t pos = 0;
 
-    if (!stream_running(s) || stream_idle(s)) {
+    if (!stream_running(s) || stream_idle(s) || stream_halted(s)) {
         return 0;
     }
 
@@ -407,7 +412,7 @@ xilinx_axidma_data_stream_can_push(StreamSink *obj,
     XilinxAXIDMAStreamSink *ds = XILINX_AXI_DMA_DATA_STREAM(obj);
     struct Stream *s = &ds->dma->streams[1];
 
-    if (!stream_running(s) || stream_idle(s)) {
+    if (!stream_running(s) || stream_idle(s) || stream_halted(s)) {
         ds->dma->notify = notify;
         ds->dma->notify_opaque = notify_opaque;
         return false;