[Qemu-devel] [PATCH 3/4] ahci: explicitly reject bad engine states on post_load

[John Snow <jsnow@redhat.com>]

Currently, we let ahci_cond_start_engines reject weird configurations
where either the DMA (CLB) or FIS engines are said to be started, but
their matching on/off control bit is toggled off.

There should be no way to achieve this, since any time you toggle the
control bit off, the status bit should always follow synchronously.

Preparing for a refactor in cond_start_engines, move the rejection logic
straight up into post_load.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 hw/ide/ahci.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
index 0653396..e856ad5 100644
--- a/hw/ide/ahci.c
+++ b/hw/ide/ahci.c
@@ -217,10 +217,6 @@ static int ahci_cond_start_engines(AHCIDevice *ad, bool allow_stop)
     } else if (pr->cmd & PORT_CMD_LIST_ON) {
         if (allow_stop) {
             ahci_unmap_clb_address(ad);
-        } else {
-            error_report("AHCI: DMA engine should be off, "
-                         "but appears to still be running");
-            return -1;
         }
     }
 
@@ -233,10 +229,6 @@ static int ahci_cond_start_engines(AHCIDevice *ad, bool allow_stop)
     } else if (pr->cmd & PORT_CMD_FIS_ON) {
         if (allow_stop) {
             ahci_unmap_fis_address(ad);
-        } else {
-            error_report("AHCI: FIS receive engine should be off, "
-                         "but appears to still be running");
-            return -1;
         }
     }
 
@@ -1567,10 +1559,23 @@ static int ahci_state_post_load(void *opaque, int version_id)
     int i, j;
     struct AHCIDevice *ad;
     NCQTransferState *ncq_tfs;
+    AHCIPortRegs *pr;
     AHCIState *s = opaque;
 
     for (i = 0; i < s->ports; i++) {
         ad = &s->dev[i];
+        pr = &ad->port_regs;
+
+        if (!(pr->cmd & PORT_CMD_START) && (pr->cmd & PORT_CMD_LIST_ON)) {
+            error_report("AHCI: DMA engine should be off, but status bit "
+                         "indicates it is still running.");
+            return -1;
+        }
+        if (!(pr->cmd & PORT_CMD_FIS_RX) && (pr->cmd & PORT_CMD_FIS_ON)) {
+            error_report("AHCI: FIS RX engine should be off, but status bit "
+                         "indicates it is still running.");
+            return -1;
+        }
 
         /* Only remap the CLB address if appropriate, disallowing a state
          * transition from 'on' to 'off' it should be consistent here. */
-- 
2.4.3