Allow vfio hotplug of a device to the domain which owns the iommu

The commit 7e72de49 didn't consider the hotplug scenarios. The patch addresses
the hotplug case whereby if atleast one of the pci function is owned by a
guest, the hotplug of other functions/devices in the same iommu group to the
same guest goes through successfully.
Signed-off-by: NShivaprasad G Bhat <sbhat@linux.vnet.ibm.com>

src/util/virhostdev.c

@@ -54,23 +54,35 @@ static virClassPtr virHostdevManagerClass;
 static void virHostdevManagerDispose(void *obj);
 static virHostdevManagerPtr virHostdevManagerNew(void);
 
+struct virHostdevIsPCINodeDeviceUsedData {
+    virHostdevManagerPtr hostdev_mgr;
+    const char *domainName;
+    const bool usesVfio;
+};
+
 static int virHostdevIsPCINodeDeviceUsed(virPCIDeviceAddressPtr devAddr, void *opaque)
 {
     virPCIDevicePtr other;
     int ret = -1;
     virPCIDevicePtr pci = NULL;
-    virHostdevManagerPtr hostdev_mgr = opaque;
+    struct virHostdevIsPCINodeDeviceUsedData *helperData = opaque;
 
     if (!(pci = virPCIDeviceNew(devAddr->domain, devAddr->bus,
                                 devAddr->slot, devAddr->function)))
         goto cleanup;
 
-    other = virPCIDeviceListFind(hostdev_mgr->activePCIHostdevs, pci);
+    other = virPCIDeviceListFind(helperData->hostdev_mgr->activePCIHostdevs,
+                                 pci);
     if (other) {
         const char *other_drvname = NULL;
         const char *other_domname = NULL;
         virPCIDeviceGetUsedBy(other, &other_drvname, &other_domname);
 
+        if (helperData->usesVfio &&
+            (other_domname && helperData->domainName) &&
+            (STREQ(other_domname, helperData->domainName)))
+            goto iommu_owner;
+
         if (other_drvname && other_domname)
             virReportError(VIR_ERR_OPERATION_INVALID,
                            _("PCI device %s is in use by "
@@ -83,6 +95,7 @@ static int virHostdevIsPCINodeDeviceUsed(virPCIDeviceAddressPtr devAddr, void *o
                            virPCIDeviceGetName(pci));
         goto cleanup;
     }
+ iommu_owner:
     ret = 0;
  cleanup:
     virPCIDeviceFree(pci);
@@ -562,6 +575,9 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
     for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) {
         virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i);
         bool strict_acs_check = !!(flags & VIR_HOSTDEV_STRICT_ACS_CHECK);
+        bool usesVfio = STREQ(virPCIDeviceGetStubDriver(dev), "vfio-pci");
+        struct virHostdevIsPCINodeDeviceUsedData data = {hostdev_mgr, dom_name,
+                                                         usesVfio};
 
         if (!virPCIDeviceIsAssignable(dev, strict_acs_check)) {
             virReportError(VIR_ERR_OPERATION_INVALID,
@@ -579,12 +595,12 @@ virHostdevPreparePCIDevices(virHostdevManagerPtr hostdev_mgr,
          * belonging to same iommu group can't be shared
          * across guests.
          */
-        if (STREQ(virPCIDeviceGetStubDriver(dev), "vfio-pci")) {
+        if (usesVfio) {
             if (virPCIDeviceAddressIOMMUGroupIterate(devAddr,
                                                      virHostdevIsPCINodeDeviceUsed,
-                                                     hostdev_mgr) < 0)
+                                                     &data) < 0)
                 goto cleanup;
-        } else if (virHostdevIsPCINodeDeviceUsed(devAddr, hostdev_mgr)) {
+        } else if (virHostdevIsPCINodeDeviceUsed(devAddr, &data)) {
             goto cleanup;
         }
     }
@@ -1544,6 +1560,8 @@ virHostdevPCINodeDeviceDetach(virHostdevManagerPtr hostdev_mgr,
                               virPCIDevicePtr pci)
 {
     virPCIDeviceAddressPtr devAddr = NULL;
+    struct virHostdevIsPCINodeDeviceUsedData data = { hostdev_mgr, NULL,
+                                                     false };
     int ret = -1;
 
     virObjectLock(hostdev_mgr->activePCIHostdevs);
@@ -1552,7 +1570,7 @@ virHostdevPCINodeDeviceDetach(virHostdevManagerPtr hostdev_mgr,
     if (!(devAddr = virPCIDeviceGetAddress(pci)))
         goto out;
 
-    if (virHostdevIsPCINodeDeviceUsed(devAddr, hostdev_mgr))
+    if (virHostdevIsPCINodeDeviceUsed(devAddr, &data))
         goto out;
 
     if (virPCIDeviceDetach(pci, hostdev_mgr->activePCIHostdevs,
@@ -1573,6 +1591,8 @@ virHostdevPCINodeDeviceReAttach(virHostdevManagerPtr hostdev_mgr,
                                 virPCIDevicePtr pci)
 {
     virPCIDeviceAddressPtr devAddr = NULL;
+    struct virHostdevIsPCINodeDeviceUsedData data = {hostdev_mgr, NULL,
+                                                     false};
     int ret = -1;
 
     virObjectLock(hostdev_mgr->activePCIHostdevs);
@@ -1581,7 +1601,7 @@ virHostdevPCINodeDeviceReAttach(virHostdevManagerPtr hostdev_mgr,
     if (!(devAddr = virPCIDeviceGetAddress(pci)))
         goto out;
 
-    if (virHostdevIsPCINodeDeviceUsed(devAddr, hostdev_mgr))
+    if (virHostdevIsPCINodeDeviceUsed(devAddr, &data))
         goto out;
 
     virPCIDeviceReattachInit(pci);