From: Niklas Cassel <niklas.cassel@wdc.com>

For NCQ, PxCI is cleared on command queued successfully.
For non-NCQ, PxCI is cleared on command completed successfully.
Successfully means ERR_STAT, BUSY and DRQ are all cleared.

A command that has ERR_STAT set, does not get to clear PxCI.
See AHCI 1.3.1, section 5.3.8, states RegFIS:Entry and RegFIS:ClearCI,
and 5.3.16.5 ERR:FatalTaskfile.

In the case of non-NCQ commands, not clearing PxCI is needed in order
for host software to be able to see which command slot that failed.

Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
---
 hw/ide/ahci.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index 9d79b071b8..366929132b 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -1518,7 +1518,8 @@ static void ahci_clear_cmd_issue(AHCIDevice *ad, uint8_t slot)
 {
     IDEState *ide_state = &ad->port.ifs[0];
 
-    if (!(ide_state->status & (BUSY_STAT | DRQ_STAT))) {
+    if (!(ide_state->status & ERR_STAT) &&
+        !(ide_state->status & (BUSY_STAT | DRQ_STAT))) {
         ad->port_regs.cmd_issue &= ~(1 << slot);
     }
 }
@@ -1527,6 +1528,7 @@ static void ahci_clear_cmd_issue(AHCIDevice *ad, uint8_t slot)
 static void ahci_cmd_done(const IDEDMA *dma)
 {
     AHCIDevice *ad = DO_UPCAST(AHCIDevice, dma, dma);
+    IDEState *ide_state = &ad->port.ifs[0];
 
     trace_ahci_cmd_done(ad->hba, ad->port_no);
 
@@ -1543,7 +1545,8 @@ static void ahci_cmd_done(const IDEDMA *dma)
      */
     ahci_write_fis_d2h(ad, true);
 
-    if (ad->port_regs.cmd_issue && !ad->check_bh) {
+    if (!(ide_state->status & ERR_STAT) &&
+        ad->port_regs.cmd_issue && !ad->check_bh) {
         ad->check_bh = qemu_bh_new(ahci_check_cmd_bh, ad);
         qemu_bh_schedule(ad->check_bh);
     }
-- 
2.40.0