enable kvm:cpu_type=host on gnt-dal cluster

This is in progress, i'm rebooting dal-node-01 as we speak and other
nodes will be progressively rebooted as well.

howto/ganeti.md

@@ -1327,7 +1327,17 @@ This will only migrate the VMs without rebooting the hosts:
     ./reboot --ganeti-migrate-back --kind=cancel -v --reason 'qemu flagged in needrestart' \
         -H fsn-node-0{1,2,3,4,5,6,7,8}.torproject.org
 
-This should cause no user-visible disruption.
+This should cause no user-visible disruption, as it migrates all the
+VMs around and back.
+
+That should reset the Qemu processes across the cluster and refresh
+the libraries Qemu depends on.
+
+If you actually need to restart the instances in place (and not
+migrate them), you need to use the `--skip-ganeti-empty` flag instead:
+
+    ./reboot --skip-ganeti-empty --kind=cancel -v --reason 'qemu flagged in needrestart' \
+        -H dal-node-0{1,2,3}.torproject.org
 
 ## Rebalancing a cluster
 
@@ -3123,6 +3133,7 @@ gnt-cluster modify -H kvm:disk_type=scsi-hd
 gnt-cluster modify -H kvm:migration_bandwidth=950
 gnt-cluster modify -H kvm:migration_downtime=500
 gnt-cluster modify -H kvm:migration_caps=postcopy-ram
+gnt-cluster modify -H kvm:cpu_type=host
 gnt-cluster modify -D drbd:c-plan-ahead=0,disk-custom='--c-plan-ahead 0'
 gnt-cluster modify --uid-pool 4000-4019
 ```
@@ -3298,7 +3309,7 @@ emulation system to the CPU on the node. But that might make the live
 migration more brittle: VMs or processes can crash after a live
 migrate because of a slightly different configuration (microcode, CPU,
 kernel and QEMU versions all play a role). So we need to find the
-lowest common demoninator in CPU families. The list of available
+lowest common denominator in CPU families. The list of available
 families supported by QEMU varies between releases, but is visible
 with:
 
@@ -3337,6 +3348,8 @@ to be verified.
 Nodes could also [grouped](http://docs.ganeti.org/docs/ganeti/3.0/html/man-gnt-group.html) to limit (automated) live migration to a
 subset of nodes.
 
+Update: this was enabled in the `gnt-dal` cluster.
+
 References:
 
  * <https://dsa.debian.org/howto/install-ganeti/>