From: Dominik Dingel <dingel@linux.vnet.ibm.com>
Date: Thu, 25 Jun 2015 21:59:39 +0000 (-0700)
Subject: s390/mm: make hugepages_supported a boot time decision
X-Git-Tag: omap-for-v4.2/fixes-rc1^2~106^2~95
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bea41197ead3;p=pandora-kernel.git

s390/mm: make hugepages_supported a boot time decision

There is a potential bug with KVM and hugetlbfs if the hardware does not
support hugepages (EDAT1).  We fix this by making EDAT1 a hard requirement
for hugepages and therefore removing and simplifying code.

As s390, with the sw-emulated hugepages, was the only user of
arch_prepare/release_hugepage I also removed theses calls from common and
other architecture code.

This patch (of 5):

By dropping support for hugepages on machines which do not have the
hardware feature EDAT1, we fix a potential s390 KVM bug.

The bug would happen if a guest is backed by hugetlbfs (not supported
currently), but does not get pagetables with PGSTE.  This would lead to
random memory overwrites.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

Reading git-diff-tree failed