fix tlb flushing for page table pages

[linux-flexiantxendom0.git] / arch / s390 / mm / pgtable.c

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 301c84d..f8ceac4 100644 (file)
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -687,8 +687,6 @@ void page_table_free(struct mm_struct *mm, unsigned long *table)
        }
 }
 
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
-
 static void __page_table_free_rcu(void *table, unsigned bit)
 {
        struct page *page;
@@ -742,7 +740,66 @@ void __tlb_remove_table(void *_table)
                free_pages((unsigned long) table, ALLOC_ORDER);
 }
 
-#endif
+static void tlb_remove_table_smp_sync(void *arg)
+{
+       /* Simply deliver the interrupt */
+}
+
+static void tlb_remove_table_one(void *table)
+{
+       /*
+        * This isn't an RCU grace period and hence the page-tables cannot be
+        * assumed to be actually RCU-freed.
+        *
+        * It is however sufficient for software page-table walkers that rely
+        * on IRQ disabling. See the comment near struct mmu_table_batch.
+        */
+       smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
+       __tlb_remove_table(table);
+}
+
+static void tlb_remove_table_rcu(struct rcu_head *head)
+{
+       struct mmu_table_batch *batch;
+       int i;
+
+       batch = container_of(head, struct mmu_table_batch, rcu);
+
+       for (i = 0; i < batch->nr; i++)
+               __tlb_remove_table(batch->tables[i]);
+
+       free_page((unsigned long)batch);
+}
+
+void tlb_table_flush(struct mmu_gather *tlb)
+{
+       struct mmu_table_batch **batch = &tlb->batch;
+
+       if (*batch) {
+               __tlb_flush_mm(tlb->mm);
+               call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
+               *batch = NULL;
+       }
+}
+
+void tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+       struct mmu_table_batch **batch = &tlb->batch;
+
+       if (*batch == NULL) {
+               *batch = (struct mmu_table_batch *)
+                       __get_free_page(GFP_NOWAIT | __GFP_NOWARN);
+               if (*batch == NULL) {
+                       __tlb_flush_mm(tlb->mm);
+                       tlb_remove_table_one(table);
+                       return;
+               }
+               (*batch)->nr = 0;
+       }
+       (*batch)->tables[(*batch)->nr++] = table;
+       if ((*batch)->nr == MAX_TABLE_BATCH)
+               tlb_table_flush(tlb);
+}
 
 /*
  * switch on pgstes for its userspace process (for kvm)