[Xen-changelog] [xen stable-4.8] x86: use 64 bit mask when masking away mfn bits

[patchbot@xxxxxxx]

commit ec7f9e1df2aa6cf8376d26eafca554c6521d2e7c
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Tue Apr 4 14:55:55 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Apr 4 14:55:55 2017 +0200

    x86: use 64 bit mask when masking away mfn bits
    
    When using _PAGE_PSE_PAT as base for a negated bit mask make sure it is
    propagated to 64 bits when applied to a 64 bit value.
    
    There seems to be only one place where this is a problem, so fix this
    by casting _PAGE_PSE_PAT to 64 bits there.
    
    Not doing so will probably lead to problems on hosts with more than
    16 TB of memory.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
    master commit: 4edb1a42e3320757e3559f17edf6903bc1777de3
    master date: 2017-03-30 15:11:24 +0200
---
 xen/arch/x86/mm/p2m-pt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index 3b025d5..9e246b6 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -452,7 +452,7 @@ static int do_recalc(struct p2m_domain *p2m, unsigned long 
gfn)
                      mfn |= _PAGE_PSE_PAT >> PAGE_SHIFT;
                 }
                 else
-                     mfn &= ~(_PAGE_PSE_PAT >> PAGE_SHIFT);
+                     mfn &= ~((unsigned long)_PAGE_PSE_PAT >> PAGE_SHIFT);
                 flags |= _PAGE_PSE;
             }
             e = l1e_from_pfn(mfn, flags);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.8

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