kvm: Enable virtio drivers based on guest os display name (#3879)

When we add new guest os, sometimes we missed the records in guest_os_hypervisor.
However, the guest disk model (virtio/ide) is determined by record in the table.
It causes the issue that some new guest os(eg Debian 8/9) uses e1000 instead of virtio nic, and ide disk instead of virtio disk.

To fix the issue permanantly, pass the guest os name in guest_os if the record for kvm is not found in guest_os_hypervisor.

Related commit:7ac9f00eeeb4cd37ec39efeba066e799b581b1a0

Author: ustcweizhou

server/src/main/java/com/cloud/hypervisor/KVMGuru.java

@@ -132,7 +132,7 @@ public VirtualMachineTO implement(VirtualMachineProfile vm) {
             guestOsMapping = _guestOsHypervisorDao.findByOsIdAndHypervisor(guestOS.getId(), getHypervisorType().toString(), host.getHypervisorVersion());
         }
         if (guestOsMapping == null || host == null) {
-            to.setPlatformEmulator("Other");
+            to.setPlatformEmulator(guestOS.getDisplayName() == null ? "Other" : guestOS.getDisplayName());
         } else {
             to.setPlatformEmulator(guestOsMapping.getGuestOsName());
         }