Subject: Re: [PATCH] powerpc/lpar: Don't crash on H_PROTECT errors

From: Tyrel Datwyler <[email-masked]>
Date: Mon, 29 Feb 2016 08:50:37 -0800

On 02/29/2016 03:52 AM, Anshuman Khandual wrote:
> There are certain condition in which H_PROTECT can return error code
> other than H_NOT_FOUND and H_SUCCESS. One such being an attempt to
> update an hpte owned by adjunct partition. Return 0 in that case so
> that user space will retry the access. In adjunct case this mean we
> will not make much progress in the user space. But atleast we get a
> chance to kill the task and avoid taking down the entire box.
> 
> Signed-off-by: Aneesh Kumar K.V <[email-masked]>
> Signed-off-by: Anshuman Khandual <[email-masked]>
> ---
>  arch/powerpc/platforms/pseries/lpar.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
> index 477290a..31bcdaf 100644
> --- a/arch/powerpc/platforms/pseries/lpar.c
> +++ b/arch/powerpc/platforms/pseries/lpar.c
> @@ -310,7 +310,7 @@ static long pSeries_lpar_hpte_updatepp(unsigned long slot,
>  
>  	pr_devel("ok\n");
>  
> -	BUG_ON(lpar_rc != H_SUCCESS);
> +	WARN_RATELIMIT(lpar_rc != H_SUCCESS, "H_PROTECT returned %lu\n", lpar_rc);

In the event that we don't get H_NOT_FOUND (which is handled earlier in
the function) or H_SUCCESS this patch assumes H_RESOURCE. It fails to
handle H_PARAMETER which is also a valid return from the H_PROTECT
hypercall.

-Tyrel

>  	return 0;
>  }