linux-kernel - [PATCH v1 5/5] KVM: s390: vsie: gmap_table

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Date:   Thu,  2 Apr 2020 20:48:19 +0200
From:   David Hildenbrand <david@...hat.com>
To:     kvm@...r.kernel.org
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        David Hildenbrand <david@...hat.com>
Subject: [PATCH v1 5/5] KVM: s390: vsie: gmap_table_walk() simplifications

Let's use asce_type where applicable. Also, simplify our sanity check for
valid table levels and convert it into a WARN_ON_ONCE(). Check if we even
have a valid gmap shadow as the very first step.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 arch/s390/mm/gmap.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index fd32ab566f57..3c801dae7988 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -790,17 +790,18 @@ static inline unsigned long *gmap_table_walk(struct gmap *gmap,
 	const int asce_type = gmap->asce & _ASCE_TYPE_MASK;
 	unsigned long *table;
 
-	if ((gmap->asce & _ASCE_TYPE_MASK) + 4 < (level * 4))
-		return NULL;
 	if (gmap_is_shadow(gmap) && gmap->removed)
 		return NULL;
 
+	if (WARN_ON_ONCE(level > (asce_type >> 2) + 1))
+		return NULL;
+
 	if (WARN_ON_ONCE(asce_type != _ASCE_TYPE_REGION1) &&
 			 gaddr & (-1UL << (31 + (asce_type >> 2) * 11)))
 		return NULL;
 
 	table = gmap->table;
-	switch (gmap->asce & _ASCE_TYPE_MASK) {
+	switch (asce_type) {
 	case _ASCE_TYPE_REGION1:
 		table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
 		if (level == 4)
-- 
2.25.1