Re: [Xen-devel] [PATCH for-4.12] x86/p2m: fix p2m_finish_type_change()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.01.19 at 11:41, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> finish_type_change() returns a negative int on error, but the
> current code checks if ( !rc ).

For the purpose of determining the backporting scope (none here)
it would be nice if in such a case you could point out the commit
introducing the breakage.

> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -1176,7 +1176,7 @@ int p2m_finish_type_change(struct domain *d,
>  
>      rc = finish_type_change(hostp2m, first_gfn, max_nr);
>  
> -    if ( !rc )
> +    if ( rc < 0 )
>          goto out;
>  
>  #ifdef CONFIG_HVM
> @@ -1193,13 +1193,13 @@ int p2m_finish_type_change(struct domain *d,
>                  rc = finish_type_change(altp2m, first_gfn, max_nr);
>                  p2m_unlock(altp2m);
>  
> -                if ( !rc )
> +                if ( rc < 0 )
>                      goto out;
>              }
>      }
>  #endif

May I ask that you also fix the other return value issue here: Either
we mean to indicate to the caller the 0/1 distinction (in which case
it should be correct, i.e. cumulative across all finish_type_change()
calls made here), which was the behavior before 0fb4b58c8b
("x86/altp2m: fix display frozen when switching to a new view early"),
or we mean to signal success to the caller only by handing back zero.

Jan



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