Re: [Xen-devel] [PATCH 2 of 3] Clip mfn to allowable width when building a PTE

["Jan Beulich" <JBeulich@xxxxxxxx>]

 >>> On 21.03.12 at 20:22, Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx> wrote:
> xen/include/asm-x86/page.h |  12 ++++++++----
>  1 files changed, 8 insertions(+), 4 deletions(-)
> 
> 
> Otherwise, INVALID_MFN tramples over high order bits used for additional 
> flags.

But is passing INVALID_PFN into these macros valid/sensible in the first
place?

Jan

> Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
> Signed-off-by: Tim Deegan <tim@xxxxxxx>
> 
> diff -r 642c0e6a01c2 -r e325da663345 xen/include/asm-x86/page.h
> --- a/xen/include/asm-x86/page.h
> +++ b/xen/include/asm-x86/page.h
> @@ -107,13 +107,17 @@
>  
>  /* Construct a pte from a pfn and access flags. */
>  #define l1e_from_pfn(pfn, flags)   \
> -    ((l1_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) 
> })
> +    ((l1_pgentry_t) { (((intpte_t)(pfn) << PAGE_SHIFT) & PADDR_MASK)    \
> +                        | put_pte_flags(flags) })
>  #define l2e_from_pfn(pfn, flags)   \
> -    ((l2_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) 
> })
> +    ((l2_pgentry_t) { (((intpte_t)(pfn) << PAGE_SHIFT) & PADDR_MASK)    \
> +                        | put_pte_flags(flags) })
>  #define l3e_from_pfn(pfn, flags)   \
> -    ((l3_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) 
> })
> +    ((l3_pgentry_t) { (((intpte_t)(pfn) << PAGE_SHIFT) & PADDR_MASK)    \
> +                        | put_pte_flags(flags) })
>  #define l4e_from_pfn(pfn, flags)   \
> -    ((l4_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) 
> })
> +    ((l4_pgentry_t) { (((intpte_t)(pfn) << PAGE_SHIFT) & PADDR_MASK)    \
> +                        | put_pte_flags(flags) })
>  
>  /* Construct a pte from a physical address and access flags. */
>  #ifndef __ASSEMBLY__
> 
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> http://lists.xen.org/xen-devel 




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