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authorJeremy Fitzhardinge <jeremy@goop.org>2007-11-28 16:21:20 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-29 09:24:52 -0800
commit2c80b01beae3db9f99a161ec216405dd694bc4c2 (patch)
treeaea1b56634dad1467eca5a53a81b6a08d7b619b5 /arch
parentc06869d660ceffec7dc0fca19ed9646ed5845c7f (diff)
xen: mask _PAGE_PCD from ptes
_PAGE_PCD maps a page with caching disabled, which is typically used for mapping harware registers. Xen never allows it to be set on a mapping, and unprivileged guests never need it since they can't see the real underlying hardware. However, some uncached mappings are made early when probing the (non-existent) APIC, and its OK to mask off the PCD flag in these cases. This became necessary because Xen started checking for this bit, rather than silently masking it off. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/xen/mmu.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index b2e32f9d007..0ac6c5dc49b 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -244,6 +244,8 @@ pte_t xen_make_pte(unsigned long long pte)
if (pte & 1)
pte = phys_to_machine(XPADDR(pte)).maddr;
+ pte &= ~_PAGE_PCD;
+
return (pte_t){ pte, pte >> 32 };
}
@@ -291,6 +293,8 @@ pte_t xen_make_pte(unsigned long pte)
if (pte & _PAGE_PRESENT)
pte = phys_to_machine(XPADDR(pte)).maddr;
+ pte &= ~_PAGE_PCD;
+
return (pte_t){ pte };
}