powerpc/mm/thp: Return pte address if we find trans_splitting.

For THP that is marked trans splitting, we return the pte.
This require the callers to handle the pmd_trans_splitting scenario,
if they care. All the current callers are either looking at pfn or
write_ok, hence we don't need to update them.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/kvm_book3s_64.h

@@ -281,11 +281,9 @@ static inline int hpte_cache_flags_ok(unsigned long ptel, unsigned long io_type)
 
 /*
  * If it's present and writable, atomically set dirty and referenced bits and
- * return the PTE, otherwise return 0. If we find a transparent hugepage
- * and if it is marked splitting we return 0;
+ * return the PTE, otherwise return 0.
  */
-static inline pte_t kvmppc_read_update_linux_pte(pte_t *ptep, int writing,
-						 unsigned int hugepage)
+static inline pte_t kvmppc_read_update_linux_pte(pte_t *ptep, int writing)
 {
 	pte_t old_pte, new_pte = __pte(0);
 
@@ -301,12 +299,6 @@ static inline pte_t kvmppc_read_update_linux_pte(pte_t *ptep, int writing,
 			cpu_relax();
 			continue;
 		}
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-		/* If hugepage and is trans splitting return None */
-		if (unlikely(hugepage &&
-			     pmd_trans_splitting(pte_pmd(old_pte))))
-			return __pte(0);
-#endif
 		/* If pte is not present return None */
 		if (unlikely(!(pte_val(old_pte) & _PAGE_PRESENT)))
 			return __pte(0);

arch/powerpc/kvm/book3s_64_mmu_hv.c

@@ -537,20 +537,17 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		}
 		/* if the guest wants write access, see if that is OK */
 		if (!writing && hpte_is_writable(r)) {
-			unsigned int hugepage_shift;
 			pte_t *ptep, pte;
 			unsigned long flags;
-
 			/*
 			 * We need to protect against page table destruction
-			 * while looking up and updating the pte.
+			 * hugepage split and collapse.
 			 */
 			local_irq_save(flags);
 			ptep = find_linux_pte_or_hugepte(current->mm->pgd,
-							 hva, &hugepage_shift);
+							 hva, NULL);
 			if (ptep) {
-				pte = kvmppc_read_update_linux_pte(ptep, 1,
-							   hugepage_shift);
+				pte = kvmppc_read_update_linux_pte(ptep, 1);
 				if (pte_write(pte))
 					write_ok = 1;
 			}

arch/powerpc/kvm/book3s_hv_rm_mmu.c

@@ -219,7 +219,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
 				local_irq_restore(flags);
 			return H_PARAMETER;
 		}
-		pte = kvmppc_read_update_linux_pte(ptep, writing, hpage_shift);
+		pte = kvmppc_read_update_linux_pte(ptep, writing);
 		if (pte_present(pte) && !pte_protnone(pte)) {
 			if (writing && !pte_write(pte))
 				/* make the actual HPTE be read-only */

arch/powerpc/mm/hugetlbpage.c

@@ -1014,12 +1014,11 @@ pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
 			 * A hugepage collapse is captured by pmd_none, because
 			 * it mark the pmd none and do a hpte invalidate.
 			 *
-			 * A hugepage split is captured by pmd_trans_splitting
-			 * because we mark the pmd trans splitting and do a
-			 * hpte invalidate
-			 *
+			 * We don't worry about pmd_trans_splitting here, The
+			 * caller if it needs to handle the splitting case
+			 * should check for that.
 			 */
-			if (pmd_none(pmd) || pmd_trans_splitting(pmd))
+			if (pmd_none(pmd))
 				return NULL;
 
 			if (pmd_huge(pmd) || pmd_large(pmd)) {