From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Dingel Date: Thu, 28 May 2015 11:52:33 +0000 Subject: [PATCH 1/5] s390/mm: make hugepages_supported a boot time decision Message-Id: <1432813957-46874-2-git-send-email-dingel@linux.vnet.ibm.com> List-Id: References: <1432813957-46874-1-git-send-email-dingel@linux.vnet.ibm.com> In-Reply-To: <1432813957-46874-1-git-send-email-dingel@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org 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. Acked-by: Martin Schwidefsky Signed-off-by: Dominik Dingel --- arch/s390/include/asm/page.h | 8 ++++---- arch/s390/kernel/setup.c | 2 ++ 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 53eacbd..0844b78 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 +#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 -#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 a5ea8bc..9ac282b 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -915,6 +915,8 @@ 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 b2c1542..f76791e 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -36,6 +36,8 @@ #endif +unsigned int HPAGE_SHIFT; + unsigned long *crst_table_alloc(struct mm_struct *mm) { struct page *page = alloc_pages(GFP_KERNEL, ALLOC_ORDER); -- 2.3.7