[RFC PATCH 1/3] hw/audio/intel-hda: Do not ignore DMA overrun errors

[Philippe Mathieu-Daudé]

Per the "High Definition Audio Specification" manual (rev. 1.0a),
section "3.3.30 Offset 5Dh: RIRBSTS - RIRB Status":

  Response Overrun Interrupt Status (RIRBOIS):

  Hardware sets this bit to a 1 when an overrun occurs in the RIRB.
  An interrupt may be generated if the Response Overrun Interrupt
  Control bit is set.

  This bit will be set if the RIRB DMA engine is not able to write
  the incoming responses to memory before additional incoming
  responses overrun the internal FIFO.

  When hardware detects an overrun, it will drop the responses which
  overrun the buffer and set the RIRBOIS status bit to indicate the
  error condition. Optionally, if the RIRBOIC is set, the hardware
  will also generate an error to alert software to the problem.

QEMU emulates the DMA engine with the stl_le_pci_dma() calls. This
function returns a MemTxResult indicating whether the DMA access
was successful.
Handle any MemTxResult error as "DMA engine is not able to write the
incoming responses to memory" and raise the Overrun Interrupt flag
when this case occurs.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/audio/intel-hda.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/hw/audio/intel-hda.c b/hw/audio/intel-hda.c
index 2b55d521503..0c1017edbbf 100644
--- a/hw/audio/intel-hda.c
+++ b/hw/audio/intel-hda.c
@@ -350,6 +350,7 @@ static void intel_hda_response(HDACodecDevice *dev, bool 
solicited, uint32_t res
     IntelHDAState *d = container_of(bus, IntelHDAState, codecs);
     hwaddr addr;
     uint32_t wp, ex;
+    MemTxResult res = MEMTX_OK;
 
     if (d->ics & ICH6_IRS_BUSY) {
         dprint(d, 2, "%s: [irr] response 0x%x, cad 0x%x\n",
@@ -368,8 +369,12 @@ static void intel_hda_response(HDACodecDevice *dev, bool 
solicited, uint32_t res
     ex = (solicited ? 0 : (1 << 4)) | dev->cad;
     wp = (d->rirb_wp + 1) & 0xff;
     addr = intel_hda_addr(d->rirb_lbase, d->rirb_ubase);
-    stl_le_pci_dma(&d->pci, addr + 8 * wp, response, attrs);
-    stl_le_pci_dma(&d->pci, addr + 8 * wp + 4, ex, attrs);
+    res |= stl_le_pci_dma(&d->pci, addr + 8 * wp, response, attrs);
+    res |= stl_le_pci_dma(&d->pci, addr + 8 * wp + 4, ex, attrs);
+    if (res != MEMTX_OK && (d->rirb_ctl & ICH6_RBCTL_OVERRUN_EN)) {
+        d->rirb_sts |= ICH6_RBSTS_OVERRUN;
+        intel_hda_update_irq(d);
+    }
     d->rirb_wp = wp;
 
     dprint(d, 2, "%s: [wp 0x%x] response 0x%x, extra 0x%x\n",
-- 
2.33.1