diff options
| author | Ian Campbell <ian.campbell@citrix.com> | 2010-02-26 17:16:00 +0000 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2010-02-27 14:41:01 -0800 |
| commit | 817a824b75b1475f1b067c8cee318c7b4d66fcde (patch) | |
| tree | 72c786e2d821344c377fe4f0b233408043c7b89a /arch/x86/xen | |
| parent | c1fd1b43831fa20c91cdd461342af8edf2e87c2f (diff) | |
x86, xen: Disable highmem PTE allocation even when CONFIG_HIGHPTE=y
There's a path in the pagefault code where the kernel deliberately
breaks its own locking rules by kmapping a high pte page without
holding the pagetable lock (in at least page_check_address). This
breaks Xen's ability to track the pinned/unpinned state of the
page. There does not appear to be a viable workaround for this
behaviour so simply disable HIGHPTE for all Xen guests.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
LKML-Reference: <1267204562-11844-1-git-send-email-ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pasi Kärkkäinen <pasik@iki.fi>
Cc: <stable@kernel.org> # .32.x: 14315592: Allow highmem user page tables to be disabled at boot time
Cc: <stable@kernel.org> # .32.x
Cc: <xen-devel@lists.xensource.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/xen')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 7 | ||||
| -rw-r--r-- | arch/x86/xen/mmu.c | 11 |
2 files changed, 13 insertions, 5 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 36daccb68642..b607239c1ba8 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -50,6 +50,7 @@ #include <asm/traps.h> #include <asm/setup.h> #include <asm/desc.h> +#include <asm/pgalloc.h> #include <asm/pgtable.h> #include <asm/tlbflush.h> #include <asm/reboot.h> @@ -1094,6 +1095,12 @@ asmlinkage void __init xen_start_kernel(void) __supported_pte_mask |= _PAGE_IOMAP; + /* + * Prevent page tables from being allocated in highmem, even + * if CONFIG_HIGHPTE is enabled. + */ + __userpte_alloc_gfp &= ~__GFP_HIGHMEM; + /* Work out if we support NX */ x86_configure_nx(); diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index bf4cd6bfe959..350a3deedf25 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1432,14 +1432,15 @@ static void *xen_kmap_atomic_pte(struct page *page, enum km_type type) { pgprot_t prot = PAGE_KERNEL; + /* + * We disable highmem allocations for page tables so we should never + * see any calls to kmap_atomic_pte on a highmem page. + */ + BUG_ON(PageHighMem(page)); + if (PagePinned(page)) prot = PAGE_KERNEL_RO; - if (0 && PageHighMem(page)) - printk("mapping highpte %lx type %d prot %s\n", - page_to_pfn(page), type, - (unsigned long)pgprot_val(prot) & _PAGE_RW ? "WRITE" : "READ"); - return kmap_atomic_prot(page, type, prot); } #endif |