[PATCH v14 08/12] mm/hmm: add lazy MMU mode support for migration in HMM pagewalk

[mpenttil]

From: Mika Penttilä <mpenttil@xxxxxxxxxx>

Add calls to lazy_mmu_mode_enable() and lazy_mmu_mode_disable()
while doing migration.

Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Leon Romanovsky <leonro@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Balbir Singh <balbirs@xxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
Suggested-by: Alistair Popple <apopple@xxxxxxxxxx>
Signed-off-by: Mika Penttilä <mpenttil@xxxxxxxxxx>
---
 mm/hmm.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index a1459bd34c04..a67a23e54551 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -371,6 +371,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
 		/* Report error for everything else */
 
 		if (hmm_vma_walk->ptelocked) {
+			lazy_mmu_mode_disable();
 			pte_unmap_unlock(ptep, hmm_vma_walk->ptl);
 			hmm_vma_walk->ptelocked = false;
 		} else {
@@ -394,6 +395,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
 	    !is_zero_pfn(pte_pfn(pte))) {
 		if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) {
 			if (hmm_vma_walk->ptelocked) {
+				lazy_mmu_mode_disable();
 				pte_unmap_unlock(ptep, hmm_vma_walk->ptl);
 				hmm_vma_walk->ptelocked = false;
 			} else {
@@ -413,6 +415,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
 
 fault:
 	if (hmm_vma_walk->ptelocked) {
+		lazy_mmu_mode_disable();
 		pte_unmap_unlock(ptep, hmm_vma_walk->ptl);
 		hmm_vma_walk->ptelocked = false;
 	} else {
@@ -510,6 +513,7 @@ static int migrate_vma_split_folio(struct folio *folio,
 	if (folio != fault_folio)
 		folio_get(folio);
 
+	lazy_mmu_mode_disable();
 	pte_unmap_unlock(ptep, hmm_vma_walk->ptl);
 	hmm_vma_walk->ptelocked = false;
 
@@ -1135,8 +1139,10 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 
 	if (minfo) {
 		ptep = pte_offset_map_lock(mm, pmdp, addr, &hmm_vma_walk->ptl);
-		if (ptep)
+		if (ptep) {
+			lazy_mmu_mode_enable();
 			hmm_vma_walk->ptelocked = true;
+		}
 	} else {
 		ptep = pte_offset_map(pmdp, addr);
 	}
@@ -1178,6 +1184,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 		flush_tlb_range(walk->vma, start, addr);
 
 	if (hmm_vma_walk->ptelocked) {
+		lazy_mmu_mode_disable();
 		pte_unmap_unlock(ptep - 1, hmm_vma_walk->ptl);
 		hmm_vma_walk->ptelocked = false;
 	} else {
-- 
2.55.0