On Fri, Mar 10, 2023 at 02:02:36PM +0100, Nico Boehr wrote:
> Diag 308 subcodes expect a physical address as their parameter.
>
> This currently is not a bug, but in the future physical and virtual
> addresses might differ.
>
> Fix the confusion by doing a virtual-to-physical conversion in the
> exported diag308() and leave the assembly wrapper __diag308() alone.
You change the prototype though ;)
> Note that several callers pass NULL as addr, this is _currently_ fine since
> virt_to_phys(0) == 0. But in the future, lowcore addresses might no
> longer be special, so make sure we pass 0 to hardware in case addr is
> NULL.
This paragraph seems to me is extra or not precise at least.
The reason for explicit NULL check is not virt_to_phys(NULL)
might return non-0 in the future, but rather virt_to_phys(NULL)
is not expected returning 0 on any architecture.
> Suggested-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxx>
> Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
> ---
> arch/s390/kernel/ipl.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
> index 5f0f5c86963a..d8b8a87626f7 100644
> --- a/arch/s390/kernel/ipl.c
> +++ b/arch/s390/kernel/ipl.c
> @@ -176,7 +176,7 @@ static bool reipl_fcp_clear;
> static bool reipl_ccw_clear;
> static bool reipl_eckd_clear;
>
> -static inline int __diag308(unsigned long subcode, void *addr)
> +static inline int __diag308(unsigned long subcode, u64 addr)
Physical addresses are unsigned longs. Why u64 then?
Also the cast to unsigned long (not seen here) becomes redundant.
> {
> union register_pair r1;
