tree 1c735ee1c90c691b0246c9bb07811030734d14e4
parent 95ca2cb57985b07f5b136405f80a5106f5b06641
author Janosch Frank <frankja@linux.vnet.ibm.com> 1462885422 +0200
committer Christian Borntraeger <borntraeger@de.ibm.com> 1465553232 +0200

KVM: s390: Limit sthyi execution

Store hypervisor information is a valid instruction not only in
supervisor state but also in problem state, i.e. the guest's
userspace. Its execution is not only computational and memory
intensive, but also has to get hold of the ipte lock to write to the
guest's memory.

This lock is not intended to be held often and long, especially not
from the untrusted guest userspace. Therefore we apply rate limiting
of sthyi executions per VM.

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Acked-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>