diff options
| -rw-r--r-- | arch/s390/include/asm/gmap.h | 2 | ||||
| -rw-r--r-- | arch/s390/mm/gmap.c | 45 |
2 files changed, 30 insertions, 17 deletions
diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h index 4a47055f58d7..54a2487efce4 100644 --- a/arch/s390/include/asm/gmap.h +++ b/arch/s390/include/asm/gmap.h @@ -27,6 +27,7 @@ * @parent: pointer to the parent gmap for shadow guest address spaces * @orig_asce: ASCE for which the shadow page table has been created * @removed: flag to indicate if a shadow guest address space has been removed + * @initialized: flag to indicate if a shadow guest address space can be used */ struct gmap { struct list_head list; @@ -49,6 +50,7 @@ struct gmap { struct gmap *parent; unsigned long orig_asce; bool removed; + bool initialized; }; /** diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index a396e58b5a43..a7dfb337e133 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -1384,7 +1384,8 @@ static void gmap_unshadow(struct gmap *sg) * @asce: ASCE for which the shadow table is created * * Returns the pointer to a gmap if a shadow table with the given asce is - * already available, otherwise NULL + * already available, ERR_PTR(-EAGAIN) if another one is just being created, + * otherwise NULL */ static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce) { @@ -1393,6 +1394,8 @@ static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce) list_for_each_entry(sg, &parent->children, list) { if (sg->orig_asce != asce || sg->removed) continue; + if (!sg->initialized) + return ERR_PTR(-EAGAIN); atomic_inc(&sg->ref_count); return sg; } @@ -1409,8 +1412,9 @@ static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce) * The shadow table will be removed automatically on any change to the * PTE mapping for the source table. * - * Returns a guest address space structure, NULL if out of memory or if - * anything goes wrong while protecting the top level pages. + * Returns a guest address space structure, ERR_PTR(-ENOMEM) if out of memory, + * ERR_PTR(-EAGAIN) if the caller has to retry and ERR_PTR(-EFAULT) if the + * parent gmap table could not be protected. */ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce) { @@ -1428,30 +1432,37 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce) limit = -1UL >> (33 - (((asce & _ASCE_TYPE_MASK) >> 2) * 11)); new = gmap_alloc(limit); if (!new) - return NULL; + return ERR_PTR(-ENOMEM); new->mm = parent->mm; new->parent = gmap_get(parent); new->orig_asce = asce; + new->initialized = false; + spin_lock(&parent->shadow_lock); + /* Recheck if another CPU created the same shadow */ + sg = gmap_find_shadow(parent, asce); + if (sg) { + spin_unlock(&parent->shadow_lock); + gmap_free(new); + return sg; + } + atomic_set(&new->ref_count, 2); + list_add(&new->list, &parent->children); + spin_unlock(&parent->shadow_lock); + /* protect after insertion, so it will get properly invalidated */ down_read(&parent->mm->mmap_sem); rc = gmap_protect_range(parent, asce & _ASCE_ORIGIN, ((asce & _ASCE_TABLE_LENGTH) + 1) * 4096, PROT_READ, PGSTE_VSIE_BIT); up_read(&parent->mm->mmap_sem); + spin_lock(&parent->shadow_lock); + new->initialized = true; if (rc) { - atomic_set(&new->ref_count, 2); - spin_lock(&parent->shadow_lock); - /* Recheck if another CPU created the same shadow */ - sg = gmap_find_shadow(parent, asce); - if (!sg) { - list_add(&new->list, &parent->children); - sg = new; - new = NULL; - } - spin_unlock(&parent->shadow_lock); - } - if (new) + list_del(&new->list); gmap_free(new); - return sg; + new = ERR_PTR(rc); + } + spin_unlock(&parent->shadow_lock); + return new; } EXPORT_SYMBOL_GPL(gmap_shadow); |