Disable KFENCE as a workaround to prevent potential kernel panics that
seem to happen in nested KVM environments (e.g., systemd autopackage
test).
Disabling this feature also allows to remove the overhead of the
periodic sampling performed by KFENCE. The regression potential is that
we may receive memory corruption bug reports (that were previously
detected explicitly by KFENCE), but in such case we have always the
option to provide a test kernel with KASAN enabled, that provides a
better coverage for this kind of bugs.
Signed-off-by: Andrea Righi <email address hidden>
When this feature is enabled the hardware is free to interpret
specification exceptions generated by the guest, instead of causing
program interruption interceptions.
This benefits (test) programs that generate a lot of specification
exceptions (roughly 4x increase in exceptions/sec).
Interceptions will occur as before if ICTL_PINT is set,
i.e. if guest debug is enabled.
There is no indication if this feature is available or not and the
hardware is free to interpret or not. So we can simply set this bit and
if the hardware ignores it we fall back to intercept 8 handling.
Signed-off-by: Janis Schoetterl-Glausch <email address hidden>
Link: https://<email address hidden>/
Reviewed-by: David Hildenbrand <email address hidden>
Reviewed-by: Christian Borntraeger <email address hidden>
Signed-off-by: Christian Borntraeger <email address hidden>
(cherry picked from commit 7119decf47d9867266459615be502e5d2cecedba)
Signed-off-by: Frank Heimes <email address hidden>
Acked-by: Juerg Haefliger <email address hidden>
Acked-by: Tim Gardner <email address hidden>
Signed-off-by: Paolo Pisati <email address hidden>
