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

Plumb the kvm_pgtable_stage2_mkyoung() callback into pKVM for
non-protected guests. It will be called later from the fault handling
path.

BACKPORT: Added kvm_pte_t return value. 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: I7d486536e3cce42b7ea97453e242da15ede6855e
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20241218194059.3670226-16-qperret@google.com


Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry-picked from commit 76f0b18b
 git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm next)
Signed-off-by: Quentin Perret <qperret@google.com>