Increase dom0 scheduling weight

Dom0 is responsible for the UI and for critical background activities.
In particular, it is on the critical path for VM start.  Therefore, it
should be prioritized over all other VMs to avoid priority inversion.

Qubes OS has always granted dom0 additional scheduling credit in the
credit scheduler.  However, Xen has since switched from the credit
scheduler to the credit2 scheduler.  Therefore, changing parameters in
the credit scheduler no longer has any effect.  Give dom0 the same
amount additional credit in the credit2 scheduler as well, so that it
does not matter which scheduler is used.

Fixes: QubesOS/qubes-issues#10778
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>

Author: DemiMarie

linux/aux-tools/startup-misc.sh

@@ -7,6 +7,7 @@ DOM0_MAXMEM=$(/usr/sbin/xl list 0 | tail -1 | awk '{ print $3 }')
 xenstore-write /local/domain/0/memory/static-max $[ $DOM0_MAXMEM * 1024 ]
 
 xl sched-credit -d 0 -w 2000
+xl sched-credit2 -d 0 -w 2000
 cp /var/lib/qubes/qubes.xml /var/lib/qubes/backup/qubes-$(date +%F-%T).xml
 
 /usr/lib/qubes/cleanup-dispvms