diff options
| 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 | |
| parent | aefbef10e3ae6e2c6e3c54f906f10b34c73a2c66 (diff) | |
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')
| -rw-r--r-- | arch/s390/include/asm/page.h | 8 | ||||
| -rw-r--r-- | arch/s390/kernel/setup.c | 2 | ||||
| -rw-r--r-- | arch/s390/mm/pgtable.c | 2 |
3 files changed, 8 insertions, 4 deletions
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h index 53eacbd4f09b..0844b780c6a4 100644 --- a/arch/s390/include/asm/page.h +++ b/arch/s390/include/asm/page.h @@ -17,7 +17,10 @@ #define PAGE_DEFAULT_ACC 0 #define PAGE_DEFAULT_KEY (PAGE_DEFAULT_ACC << 4) -#define HPAGE_SHIFT 20 +#include <asm/setup.h> +#ifndef __ASSEMBLY__ + +extern unsigned int HPAGE_SHIFT; #define HPAGE_SIZE (1UL << HPAGE_SHIFT) #define HPAGE_MASK (~(HPAGE_SIZE - 1)) #define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) @@ -27,9 +30,6 @@ #define ARCH_HAS_PREPARE_HUGEPAGE #define ARCH_HAS_HUGEPAGE_CLEAR_FLUSH -#include <asm/setup.h> -#ifndef __ASSEMBLY__ - static inline void storage_key_init_range(unsigned long start, unsigned long end) { #if PAGE_DEFAULT_KEY 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. */ diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index b33f66110ca9..16154720bdb6 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -31,6 +31,8 @@ #define ALLOC_ORDER 2 #define FRAG_MASK 0x03 +unsigned int HPAGE_SHIFT; + unsigned long *crst_table_alloc(struct mm_struct *mm) { struct page *page = alloc_pages(GFP_KERNEL, ALLOC_ORDER); |