s390/mm,kvm: flush gmap address space with IDTE

The __tlb_flush_mm() helper uses a global flush if the mm struct
has a gmap structure attached to it. Replace the global flush with
two individual flushes by means of the IDTE instruction if only a
single gmap is attached the the mm.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 2ce6bb3bab32..3ba622702ce4 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -94,6 +94,7 @@ out:
 struct gmap *gmap_create(struct mm_struct *mm, unsigned long limit)
 {
         struct gmap *gmap;
+        unsigned long gmap_asce;
 
         gmap = gmap_alloc(limit);
         if (!gmap)
@@ -101,6 +102,11 @@ struct gmap *gmap_create(struct mm_struct *mm, unsigned long limit)
         gmap->mm = mm;
         spin_lock(&mm->context.gmap_lock);
         list_add_rcu(&gmap->list, &mm->context.gmap_list);
+        if (list_is_singular(&mm->context.gmap_list))
+                gmap_asce = gmap->asce;
+        else
+                gmap_asce = -1UL;
+        WRITE_ONCE(mm->context.gmap_asce, gmap_asce);
         spin_unlock(&mm->context.gmap_lock);
         return gmap;
 }
@@ -230,6 +236,7 @@ EXPORT_SYMBOL_GPL(gmap_put);
 void gmap_remove(struct gmap *gmap)
 {
         struct gmap *sg, *next;
+        unsigned long gmap_asce;
 
         /* Remove all shadow gmaps linked to this gmap */
         if (!list_empty(&gmap->children)) {
@@ -243,6 +250,14 @@ void gmap_remove(struct gmap *gmap)
         /* Remove gmap from the pre-mm list */
         spin_lock(&gmap->mm->context.gmap_lock);
         list_del_rcu(&gmap->list);
+        if (list_empty(&gmap->mm->context.gmap_list))
+                gmap_asce = 0;
+        else if (list_is_singular(&gmap->mm->context.gmap_list))
+                gmap_asce = list_first_entry(&gmap->mm->context.gmap_list,
+                                             struct gmap, list)->asce;
+        else
+                gmap_asce = -1UL;
+        WRITE_ONCE(gmap->mm->context.gmap_asce, gmap_asce);
         spin_unlock(&gmap->mm->context.gmap_lock);
         synchronize_rcu();
         /* Put reference */