scsi: Fix SCSI bus reset

When the controller raises the SCSI reset line, we have to perform the
requested reset on all disks attached to the controller's bus. Moreover,
reset is edge triggered, so avoid repeating it if the line was already
high.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/lsi53c895a.c

diff --git a/hw/lsi53c895a.c b/hw/lsi53c895a.c
index 1bb1caf..bd7b661 100644
--- a/hw/lsi53c895a.c
+++ b/hw/lsi53c895a.c
@@ -1590,8 +1590,19 @@
             BADF("Immediate Arbritration not implemented\n");
         }
         if (val & LSI_SCNTL1_RST) {
-            s->sstat0 |= LSI_SSTAT0_RST;
-            lsi_script_scsi_interrupt(s, LSI_SIST0_RST, 0);
+            if (!(s->sstat0 & LSI_SSTAT0_RST)) {
+                DeviceState *dev;
+                int id;
+
+                for (id = 0; id < s->bus.ndev; id++) {
+                    if (s->bus.devs[id]) {
+                        dev = &s->bus.devs[id]->qdev;
+                        dev->info->reset(dev);
+                    }
+                }
+                s->sstat0 |= LSI_SSTAT0_RST;
+                lsi_script_scsi_interrupt(s, LSI_SIST0_RST, 0);
+            }
         } else {
             s->sstat0 &= ~LSI_SSTAT0_RST;
         }