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s390/mm: allow to check if a gmap shadow is valid

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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 <schwidefsky@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
David Hildenbrand 2016-05-27 18:57:33 +02:00 committed by Christian Borntraeger
parent 4a49443924
commit 5b6c963bce
2 changed files with 21 additions and 0 deletions
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1
arch/s390/include/asm/gmap.h
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@ -109,6 +109,7 @@ int gmap_read_table(struct gmap *gmap, unsigned long gaddr, unsigned long *val);
struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
int edat_level);
int gmap_shadow_valid(struct gmap *sg, unsigned long asce, int edat_level);
int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
int fake);
int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,

20
arch/s390/mm/gmap.c
View file

@ -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