KVM: Fix two memory management related problems on s390x

Thomas Huthrequested to merge
thuth/kernel-cs-10:RHEL-92226 into main

JIRA: https://issues.redhat.com/browse/RHEL-92226

JIRA: https://issues.redhat.com/browse/RHEL-58218

Fix a call trace that can happen with the debug kernel on s390x when starting a nested guest, and fix a problem that occurs when backing the memory of a KVM guest with real files.

Note: I've included some selftest patches at the beginning of the series to be able to cherry-pick the other patches cleanly. These selftest patches at the beginning of the patch series show up as having conflicts in "revumatic", but that's only due to a rename of a subfolder from "s390x" to "s390", the changes themselves are clean.

Resolves: RHEL-92226

Resolves: RHEL-58218

Signed-off-by: Thomas Huth thuth@redhat.com

Edited by Thomas Huth

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