pciResetDevice: use inactive devices to determine safe reset

When doing a PCI secondary bus reset, we must be sure that there are no
active devices on the same bus segment.  The active device tracking is
designed to only track host devices that are active in use by guests.
This ignores host devices that are actively in use by the host.  So the
current logic will reset host devices.

Switch this logic around and allow sbus reset when we are assigning all
devices behind a bridge to the same guest at guest startup or as a result
of a single attach-device command.

* src/util/pci.h: change signature of pciResetDevice to add an
  inactive devices list
* src/qemu/qemu_driver.c src/xen/xen_driver.c: use (or not) the new
  functionality of pciResetDevice() depending on the place of use
* src/util/pci.c: implement the interface and logic changes

4 files changed, 18 insertions, 15 deletions

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 63ddd35fb..45a2cfcaa 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -3107,7 +3107,7 @@ qemuPrepareHostdevPCIDevices(struct qemud_driver *driver,
      * reset them */
     for (i = 0; i < pciDeviceListCount(pcidevs); i++) {
         pciDevice *dev = pciDeviceListGet(pcidevs, i);
-        if (pciResetDevice(dev, driver->activePciHostdevs) < 0)
+        if (pciResetDevice(dev, driver->activePciHostdevs, pcidevs) < 0)
             goto cleanup;
     }
 
@@ -3253,7 +3253,7 @@ qemuDomainReAttachHostdevDevices(struct qemud_driver *driver,
 
     for (i = 0; i < pciDeviceListCount(pcidevs); i++) {
         pciDevice *dev = pciDeviceListGet(pcidevs, i);
-        if (pciResetDevice(dev, driver->activePciHostdevs) < 0) {
+        if (pciResetDevice(dev, driver->activePciHostdevs, pcidevs) < 0) {
             virErrorPtr err = virGetLastError();
             VIR_ERROR(_("Failed to reset PCI device: %s"),
                       err ? err->message : _("unknown error"));
@@ -8995,7 +8995,7 @@ static int qemudDomainDetachHostPciDevice(struct qemud_driver *driver,
     else {
         pciDeviceSetManaged(pci, detach->managed);
         pciDeviceListDel(driver->activePciHostdevs, pci);
-        if (pciResetDevice(pci, driver->activePciHostdevs) < 0)
+        if (pciResetDevice(pci, driver->activePciHostdevs, NULL) < 0)
             ret = -1;
         qemudReattachManagedDevice(pci, driver);
         pciFreeDevice(pci);
@@ -11620,7 +11620,7 @@ qemudNodeDeviceReset (virNodeDevicePtr dev)
 
     qemuDriverLock(driver);
 
-    if (pciResetDevice(pci, driver->activePciHostdevs) < 0)
+    if (pciResetDevice(pci, driver->activePciHostdevs, NULL) < 0)
         goto out;
 
     ret = 0;
diff --git a/src/util/pci.c b/src/util/pci.c
index 6d0ca24f6..1c10067d9 100644
--- a/src/util/pci.c
+++ b/src/util/pci.c
@@ -440,11 +440,11 @@ pciDetectPowerManagementReset(pciDevice *dev)
     return 0;
 }
 
-/* Any active devices other than the one supplied on the same domain/bus ? */
+/* Any active devices on the same domain/bus ? */
 static int
 pciSharesBusWithActive(pciDevice *dev, pciDevice *check, void *data)
 {
-    pciDeviceList *activeDevs = data;
+    pciDeviceList *inactiveDevs = data;
 
     /* Different domain, different bus, or simply identical device */
     if (dev->domain != check->domain ||
@@ -453,7 +453,8 @@ pciSharesBusWithActive(pciDevice *dev, pciDevice *check, void *data)
          dev->function == check->function))
         return 0;
 
-    if (activeDevs && !pciDeviceListFind(activeDevs, check))
+    /* same bus, but inactive, i.e. about to be assigned to guest */
+    if (inactiveDevs && pciDeviceListFind(inactiveDevs, check))
         return 0;
 
     return 1;
@@ -461,11 +462,11 @@ pciSharesBusWithActive(pciDevice *dev, pciDevice *check, void *data)
 
 static pciDevice *
 pciBusContainsActiveDevices(pciDevice *dev,
-                            pciDeviceList *activeDevs)
+                            pciDeviceList *inactiveDevs)
 {
     pciDevice *active = NULL;
     if (pciIterDevices(pciSharesBusWithActive,
-                       dev, &active, activeDevs) < 0)
+                       dev, &active, inactiveDevs) < 0)
         return NULL;
     return active;
 }
@@ -512,7 +513,7 @@ pciGetParentDevice(pciDevice *dev)
  */
 static int
 pciTrySecondaryBusReset(pciDevice *dev,
-                        pciDeviceList *activeDevs)
+                        pciDeviceList *inactiveDevs)
 {
     pciDevice *parent, *conflict;
     uint8_t config_space[PCI_CONF_LEN];
@@ -524,7 +525,7 @@ pciTrySecondaryBusReset(pciDevice *dev,
      * In future, we could allow it so long as those devices
      * are not in use by the host or other guests.
      */
-    if ((conflict = pciBusContainsActiveDevices(dev, activeDevs))) {
+    if ((conflict = pciBusContainsActiveDevices(dev, inactiveDevs))) {
         pciReportError(VIR_ERR_NO_SUPPORT,
                        _("Active %s devices on bus with %s, not doing bus reset"),
                        conflict->name, dev->name);
@@ -642,7 +643,8 @@ pciInitDevice(pciDevice *dev)
 
 int
 pciResetDevice(pciDevice *dev,
-               pciDeviceList *activeDevs)
+               pciDeviceList *activeDevs,
+               pciDeviceList *inactiveDevs)
 {
     int ret = -1;
 
@@ -670,7 +672,7 @@ pciResetDevice(pciDevice *dev,
 
     /* Bus reset is not an option with the root bus */
     if (ret < 0 && dev->bus != 0)
-        ret = pciTrySecondaryBusReset(dev, activeDevs);
+        ret = pciTrySecondaryBusReset(dev, inactiveDevs);
 
     if (ret < 0) {
         virErrorPtr err = virGetLastError();
diff --git a/src/util/pci.h b/src/util/pci.h
index 9aef81f9e..b767930bb 100644
--- a/src/util/pci.h
+++ b/src/util/pci.h
@@ -35,7 +35,8 @@ void       pciFreeDevice     (pciDevice     *dev);
 int        pciDettachDevice  (pciDevice     *dev, pciDeviceList *activeDevs);
 int        pciReAttachDevice (pciDevice     *dev, pciDeviceList *activeDevs);
 int        pciResetDevice    (pciDevice     *dev,
-                              pciDeviceList *activeDevs);
+                              pciDeviceList *activeDevs,
+                              pciDeviceList *inactiveDevs);
 void      pciDeviceSetManaged(pciDevice     *dev,
                               unsigned       managed);
 unsigned  pciDeviceGetManaged(pciDevice     *dev);
diff --git a/src/xen/xen_driver.c b/src/xen/xen_driver.c
index b55e49453..d121ea4c3 100644
--- a/src/xen/xen_driver.c
+++ b/src/xen/xen_driver.c
@@ -1892,7 +1892,7 @@ xenUnifiedNodeDeviceReset (virNodeDevicePtr dev)
     if (!pci)
         return -1;
 
-    if (pciResetDevice(pci, NULL) < 0)
+    if (pciResetDevice(pci, NULL, NULL) < 0)
         goto out;
 
     ret = 0;