Improve PCI host device reset error message

Currently, if we are unable to reset a PCI device we return a fairly
generic 'No PCI reset capability available' error message.

Fix that by returning an error from the individual reset messages and
using that error to construct the higher level error mesage.

* src/pci.c: set errors in pciTryPowerManagementReset() and
  pciTrySecondaryBusReset() on failure; use those error messages
  in pciResetDevice(), or explain that no reset support is available

src/pci.c

@@ -456,15 +456,18 @@ pciTrySecondaryBusReset(virConnectPtr conn, pciDevice *dev)
      * are not in use by the host or other guests.
      */
     if (pciBusContainsOtherDevices(conn, dev)) {
-        VIR_WARN("Other devices on bus with %s, not doing bus reset",
-                 dev->name);
+        pciReportError(conn, VIR_ERR_NO_SUPPORT,
+                       _("Other devices on bus with %s, not doing bus reset"),
+                       dev->name);
         return -1;
     }
 
     /* Find the parent bus */
     parent = pciGetParentDevice(conn, dev);
     if (!parent) {
-        VIR_WARN("Failed to find parent device for %s", dev->name);
+        pciReportError(conn, VIR_ERR_NO_SUPPORT,
+                       _("Failed to find parent device for %s"),
+                       dev->name);
         return -1;
     }
 
@@ -475,7 +478,9 @@ pciTrySecondaryBusReset(virConnectPtr conn, pciDevice *dev)
      * are multiple devices/functions
      */
     if (pciRead(dev, 0, config_space, PCI_CONF_LEN) < 0) {
-        VIR_WARN("Failed to save PCI config space for %s", dev->name);
+        pciReportError(conn, VIR_ERR_NO_SUPPORT,
+                       _("Failed to save PCI config space for %s"),
+                       dev->name);
         goto out;
     }
 
@@ -492,9 +497,12 @@ pciTrySecondaryBusReset(virConnectPtr conn, pciDevice *dev)
 
     usleep(200 * 1000); /* sleep 200ms */
 
-    if (pciWrite(dev, 0, config_space, PCI_CONF_LEN) < 0)
-        VIR_WARN("Failed to restore PCI config space for %s", dev->name);
-
+    if (pciWrite(dev, 0, config_space, PCI_CONF_LEN) < 0) {
+        pciReportError(conn, VIR_ERR_NO_SUPPORT,
+                       _("Failed to restore PCI config space for %s"),
+                       dev->name);
+        goto out;
+    }
     ret = 0;
 out:
     pciFreeDevice(conn, parent);
@@ -516,7 +524,9 @@ pciTryPowerManagementReset(virConnectPtr conn ATTRIBUTE_UNUSED, pciDevice *dev)
 
     /* Save and restore the device's config space. */
     if (pciRead(dev, 0, &config_space[0], PCI_CONF_LEN) < 0) {
-        VIR_WARN("Failed to save PCI config space for %s", dev->name);
+        pciReportError(conn, VIR_ERR_NO_SUPPORT,
+                       _("Failed to save PCI config space for %s"),
+                       dev->name);
         return -1;
     }
 
@@ -533,8 +543,12 @@ pciTryPowerManagementReset(virConnectPtr conn ATTRIBUTE_UNUSED, pciDevice *dev)
 
     usleep(10 * 1000); /* sleep 10ms */
 
-    if (pciWrite(dev, 0, &config_space[0], PCI_CONF_LEN) < 0)
-        VIR_WARN("Failed to restore PCI config space for %s", dev->name);
+    if (pciWrite(dev, 0, &config_space[0], PCI_CONF_LEN) < 0) {
+        pciReportError(conn, VIR_ERR_NO_SUPPORT,
+                       _("Failed to restore PCI config space for %s"),
+                       dev->name);
+        return -1;
+    }
 
     return 0;
 }
@@ -582,10 +596,14 @@ pciResetDevice(virConnectPtr conn, pciDevice *dev)
     if (ret < 0 && dev->bus != 0)
         ret = pciTrySecondaryBusReset(conn, dev);
 
-    if (ret < 0)
+    if (ret < 0) {
+        virErrorPtr err = virGetLastError();
         pciReportError(conn, VIR_ERR_NO_SUPPORT,
-                       _("No PCI reset capability available for %s"),
-                       dev->name);
+                       _("Unable to reset PCI device %s: %s"),
+                       dev->name,
+                       err ? err->message : _("no FLR, PM reset or bus reset available"));
+    }
+
     return ret;
 }
 

src/qemu_driver.c

@@ -1465,9 +1465,9 @@ qemuDomainReAttachHostDevices(virConnectPtr conn, virDomainDefPtr def)
             continue;
         }
 
-        if (pciDettachDevice(conn, dev) < 0) {
+        if (pciReAttachDevice(conn, dev) < 0) {
             virErrorPtr err = virGetLastError();
-            VIR_ERROR(_("Failed to reset PCI device: %s\n"),
+            VIR_ERROR(_("Failed to re-attach PCI device: %s\n"),
                       err ? err->message : "");
             virResetError(err);
         }