KVM: arm64: pkvm: Use the mm_ops indirection for cache maintenance

CMOs issued from EL2 cannot directly use the kernel helpers,
as EL2 doesn't have a mapping of the guest pages. Oops.

Instead, use the mm_ops indirection to use helpers that will
perform a mapping at EL2 and allow the CMO to be effective.

Fixes: 25aa2869 ("KVM: arm64: Move guest CMOs to the fault handlers")
Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220114125038.1336965-1-maz@kernel.org

arch/arm64/kvm/hyp/pgtable.c

@@ -983,13 +983,9 @@ static int stage2_unmap_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	 */
 	stage2_put_pte(ptep, mmu, addr, level, mm_ops);
 
-	if (need_flush) {
-		kvm_pte_t *pte_follow = kvm_pte_follow(pte, mm_ops);
-
-		dcache_clean_inval_poc((unsigned long)pte_follow,
-				    (unsigned long)pte_follow +
-					    kvm_granule_size(level));
-	}
+	if (need_flush && mm_ops->dcache_clean_inval_poc)
+		mm_ops->dcache_clean_inval_poc(kvm_pte_follow(pte, mm_ops),
+					       kvm_granule_size(level));
 
 	if (childp)
 		mm_ops->put_page(childp);
@@ -1151,15 +1147,13 @@ static int stage2_flush_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
 	struct kvm_pgtable *pgt = arg;
 	struct kvm_pgtable_mm_ops *mm_ops = pgt->mm_ops;
 	kvm_pte_t pte = *ptep;
-	kvm_pte_t *pte_follow;
 
 	if (!kvm_pte_valid(pte) || !stage2_pte_cacheable(pgt, pte))
 		return 0;
 
-	pte_follow = kvm_pte_follow(pte, mm_ops);
-	dcache_clean_inval_poc((unsigned long)pte_follow,
-			    (unsigned long)pte_follow +
-				    kvm_granule_size(level));
+	if (mm_ops->dcache_clean_inval_poc)
+		mm_ops->dcache_clean_inval_poc(kvm_pte_follow(pte, mm_ops),
+					       kvm_granule_size(level));
 	return 0;
 }