BACKPORT: FROMGIT: KVM: arm64: Introduce __pkvm_host_test_clear_young_guest()

Plumb the kvm_stage2_test_clear_young() callback into pKVM for
non-protected guest. It will be later be called from MMU notifiers.

BACKPORT: Temporarily hardcoded order to 0 for
 __check_host_shared_guest() check. Support for THP will be added later.

Bug: 357781595
Bug: 235345873
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Change-Id: Ia432eb06394ab2cf909608d1367211ff4caa5f2b
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20241218194059.3670226-15-qperret@google.com


Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit 56ab4de3
 git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm next)
Signed-off-by: Quentin Perret <qperret@google.com>