In the Linux kernel, the following vulnerability has been resolved:
KVM: s390: Fix _gaccess_shadow_fault()
In some circumstances, it is possible that the page of nested guest
memory that is being shadowed is not present at all in the parent guest
gmap. dat_entry_walk() will not find any leaf entry and return with
-ENOENT, which will erroneously be propagated all the way to userspace.
Fix by manually calling gmap_link() on the memory of the nested guest
that is being shadowed if the mapping was not already present.