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| author | Dominik Dingel <dingel@linux.vnet.ibm.com> | 2015-06-25 14:59:39 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-06-25 17:00:35 -0700 |
| commit | bea41197ead3e03308bdd10c11db3ce91ae5c8ab (patch) | |
| tree | d05c10b8364ee6a1892c9d613ed16cec70897f7f /arch/s390/kernel | |
| parent | aefbef10e3ae6e2c6e3c54f906f10b34c73a2c66 (diff) | |
| download | linux-bea41197ead3e03308bdd10c11db3ce91ae5c8ab.tar.bz2 | |
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>
Diffstat (limited to 'arch/s390/kernel')
| -rw-r--r-- | arch/s390/kernel/setup.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c index af4f41d52cde..73941bf42350 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -880,6 +880,8 @@ void __init setup_arch(char **cmdline_p) */ setup_hwcaps(); + HPAGE_SHIFT = MACHINE_HAS_HPAGE ? 20 : 0; + /* * Create kernel page tables and switch to virtual addressing. */ |