[Xen-devel] [PATCH] xen/x86: use 64 bit mask when masking away mfn bits

[Juergen Gross <jgross@xxxxxxxx>]

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>
---
This patch should be considered for backporting.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 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 07e2ccd..268b232 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -450,7 +450,7 @@ 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);
-- 
2.10.2


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