Re: [Xen-devel] [PATCH] remove useless super page recomputing in ept_set_entry

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

Would it make sense to turn this check on in DEBUG mode?  It can't be
that expensive if it's currently on all the time.

It's OK to code with assumptions about what some other part of the
code is doing, but it's always good to add checks (in DEBUG mode) to
catch problems if the assumptions change.

 -George

On Tue, Jun 29, 2010 at 7:06 PM, Li, Xin <xin.li@xxxxxxxxx> wrote:
> VMX: remove useless super page recomputing in ept_set_entry.
>
> Caller to ept_set_entry must give a valid order that hardware supports, see 
> set_p2m_entry in p2m.c.
>
> Signed-off-by: Xin Li <xin.li@xxxxxxxxx>
>
> diff -r a6d5b76abdcb xen/arch/x86/mm/hap/p2m-ept.c
> --- a/xen/arch/x86/mm/hap/p2m-ept.c Tue Jun 29 18:20:14 2010 +0100
> +++ b/xen/arch/x86/mm/hap/p2m-ept.c Wed Jun 30 09:59:40 2010 +0800
> @@ -307,18 +307,10 @@
>     }
>     else
>     {
> -        int num = order / EPT_TABLE_ORDER;
>         int level;
>         ept_entry_t *split_ept_entry;
>
> -        if ( (num >= 2) && hvm_hap_has_1gb(d) )
> -            num = 2;
> -        else if ( (num >= 1) && hvm_hap_has_2mb(d) )
> -            num = 1;
> -        else
> -            num = 0;
> -
> -        for ( level = split_level; level > num ; level-- )
> +        for ( level = split_level; level > walk_level ; level-- )
>         {
>             rv = ept_split_large_page(d, &table, &index, gfn, level);
>             if ( !rv )
>
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>

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