KVM: arm64: Expand valid block mappings to FEAT_LPA/LPA2 support

With 52bit PAs, block mappings can exist at different levels (such
as level 0 for 4kB pages, or level 1 for 16kB and 64kB pages).

Account for this in walk_s1().

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Marc Zyngier

arch/arm64/kvm/at.c

@@ -448,11 +448,11 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 
 		switch (BIT(wi->pgshift)) {
 		case SZ_4K:
-			valid_block = level == 1 || level == 2;
+			valid_block = level == 1 || level == 2 || (wi->pa52bit && level == 0);
 			break;
 		case SZ_16K:
 		case SZ_64K:
-			valid_block = level == 2;
+			valid_block = level == 2 || (wi->pa52bit && level == 1);
 			break;
 		}