Re: [Xen-devel] [PATCH 3/4] x86/EPT: fix pinned cache attribute range checking

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Wednesday, April 23, 2014 4:41 PM
> 
> This wasn't done properly by 4d66f069 ("x86: fix pinned cache attribute
> handling"): The passed in GFN shouldn't be assumed to be order aligned.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

> 
> --- a/xen/arch/x86/hvm/mtrr.c
> +++ b/xen/arch/x86/hvm/mtrr.c
> @@ -589,6 +589,7 @@ int hvm_get_mem_pinned_cacheattr(
>      uint32_t *type)
>  {
>      struct hvm_mem_pinned_cacheattr_range *range;
> +    uint64_t mask = ~(uint64_t)0 << order;
>      int rc = 0;
> 
>      *type = ~0;
> @@ -601,15 +602,15 @@ int hvm_get_mem_pinned_cacheattr(
> 
> &d->arch.hvm_domain.pinned_cacheattr_ranges,
>                                list )
>      {
> -        if ( (guest_fn >= range->start) &&
> -             (guest_fn + (1UL << order) - 1 <= range->end) )
> +        if ( ((guest_fn & mask) >= range->start) &&
> +             ((guest_fn | ~mask) <= range->end) )
>          {
>              *type = range->type;
>              rc = 1;
>              break;
>          }
> -        if ( (guest_fn <= range->end) &&
> -             (range->start <= guest_fn + (1UL << order) - 1) )
> +        if ( ((guest_fn & mask) <= range->end) &&
> +             (range->start <= (guest_fn | ~mask)) )
>          {
>              rc = -1;
>              break;
> 
> 


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