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authorIan Campbell <ian.campbell@citrix.com>2010-02-26 17:16:00 +0000
committerH. Peter Anvin <hpa@zytor.com>2010-02-27 14:41:01 -0800
commit817a824b75b1475f1b067c8cee318c7b4d66fcde (patch)
tree72c786e2d821344c377fe4f0b233408043c7b89a /arch/x86/xen/mmu.c
parentc1fd1b43831fa20c91cdd461342af8edf2e87c2f (diff)
downloadlinux-linaro-android-817a824b75b1475f1b067c8cee318c7b4d66fcde.tar.gz
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/mmu.c')
-rw-r--r--arch/x86/xen/mmu.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index bf4cd6bfe95..350a3deedf2 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