From 5b6c963bcef5c3a857e3f8ba84aa9380069fc95f Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 27 May 2016 18:57:33 +0200 Subject: s390/mm: allow to check if a gmap shadow is valid It will be very helpful to have a mechanism to check without any locks if a given gmap shadow is still valid and matches the given properties. Acked-by: Martin Schwidefsky Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger --- arch/s390/mm/gmap.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'arch/s390/mm/gmap.c') diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index 4a1434bc2f0e..d00e4abb559e 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -1407,6 +1407,26 @@ static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce, return NULL; } +/** + * gmap_shadow_valid - check if a shadow guest address space matches the + * given properties and is still valid + * @sg: pointer to the shadow guest address space structure + * @asce: ASCE for which the shadow table is requested + * @edat_level: edat level to be used for the shadow translation + * + * Returns 1 if the gmap shadow is still valid and matches the given + * properties, the caller can continue using it. Returns 0 otherwise, the + * caller has to request a new shadow gmap in this case. + * + */ +int gmap_shadow_valid(struct gmap *sg, unsigned long asce, int edat_level) +{ + if (sg->removed) + return 0; + return sg->orig_asce == asce && sg->edat_level == edat_level; +} +EXPORT_SYMBOL_GPL(gmap_shadow_valid); + /** * gmap_shadow - create/find a shadow guest address space * @parent: pointer to the parent gmap -- cgit v1.2.3