Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2c80b01beae3db9f99a161ec216405dd694bc4c2
Commit:     2c80b01beae3db9f99a161ec216405dd694bc4c2
Parent:     c06869d660ceffec7dc0fca19ed9646ed5845c7f
Author:     Jeremy Fitzhardinge <[EMAIL PROTECTED]>
AuthorDate: Wed Nov 28 16:21:20 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Nov 29 09:24:52 2007 -0800

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 arch/x86/xen/mmu.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index b2e32f9..0ac6c5d 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 };
 }
 
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