Re: [Xen-devel] [PATCH] p2m/ept: pass correct level to atomic_write_ept_entry in ept_invalidate_emt

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

> From: Roger Pau Monne [mailto:roger.pau@xxxxxxxxxx]
> Sent: Tuesday, August 20, 2019 11:38 PM
> 
> The level passed to ept_invalidate_emt corresponds to the EPT entry
> passed as the mfn parameter, which is a pointer to an EPT page table,
> hence the entries in that page table will have one level less than the
> parent.
> 
> Fix the call to atomic_write_ept_entry to pass the correct level, ie:
> one level less than the parent.
> 
> Fixes: 50fe6e73705 ('pvh dom0: add and remove foreign pages')
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx>
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>
> Cc: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
> Cc: Paul Durrant <paul.durrant@xxxxxxxxxx>
> ---
>  xen/arch/x86/mm/p2m-ept.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
> index 6b8468c793..23ae6e9da3 100644
> --- a/xen/arch/x86/mm/p2m-ept.c
> +++ b/xen/arch/x86/mm/p2m-ept.c
> @@ -367,7 +367,7 @@ static bool_t ept_invalidate_emt(struct p2m_domain
> *p2m, mfn_t mfn,
>          e.emt = MTRR_NUM_TYPES;
>          if ( recalc )
>              e.recalc = 1;
> -        rc = atomic_write_ept_entry(p2m, &epte[i], e, level);
> +        rc = atomic_write_ept_entry(p2m, &epte[i], e, level - 1);
>          ASSERT(rc == 0);
>          changed = 1;
>      }

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

One small comment about readability. What about renaming 'level'
to 'parent_level' in this function?

Thanks
Kevin
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