Re: [PATCH v2] xen/arm: p2m_set_entry reuse mask variables

[Julien Grall <julien@xxxxxxx>]

Hi,

On 26/04/2022 16:49, Paran Lee wrote:
> Reuse mask variables on order shift duplicated calculation.
>
> Signed-off-by: Paran Lee <p4ranlee@xxxxxxxxx>
> ---
>   xen/arch/arm/p2m.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
It is common to add a changelog after "---". This helps the reviewer to 
know what changed in your patch.
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 1d1059f7d2..cdb3b56aa1 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1118,11 +1118,12 @@ int p2m_set_entry(struct p2m_domain *p2m,
>           if ( rc )
>               break;
>   
> -        sgfn = gfn_add(sgfn, (1 << order));
> +        mask = 1UL << order;
"1UL << order" refers to the number of pages and not a mask. So I don't 
think re-using the local variable 'mask' is a good idea because the code 
is a lot more confusing.
Instead, I think your other patch is the way to go with a small tweak to 
use 1UL (which BTW should be mentioned in the commit message).
Either Stefano or I can deal with the change on commit.

Cheers,

--
Julien Grall