Re: [PATCH 2/6] s390: implement nospec_[load|ptr]

David Hildenbrand
2018-01-17T13:58:45Z

On 17.01.2018 10:48, Martin Schwidefsky wrote:
> Implement nospec_load() and nospec_ptr() for s390 with the new
> gmb() barrier between the boundary condition and the load that
> may not be done speculatively.
>
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
> ---
> arch/s390/include/asm/barrier.h | 38 ++++++++++++++++++++++++++++++++++++++
> arch/s390/kernel/alternative.c | 7 +++++++
> 2 files changed, 45 insertions(+)
>
> diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
> index 1043260..b8836a6 100644
> --- a/arch/s390/include/asm/barrier.h
> +++ b/arch/s390/include/asm/barrier.h
> @@ -8,6 +8,8 @@
> #ifndef __ASM_BARRIER_H
> #define __ASM_BARRIER_H
>
> +#include <asm/alternative.h>
> +
> /*
> * Force strict CPU ordering.
> * And yes, this is required on UP too when we're talking
> @@ -23,6 +25,42 @@
>
> #define mb() do { asm volatile(__ASM_BARRIER : : : "memory"); } while (0)
>
> +static inline void gmb(void)
> +{
> + asm volatile(
> + ALTERNATIVE("", ".long 0xb2e8f000", 81)
> + : : : "memory");
> +}

Just to be sure:

There are now 2 new facilities:

81 and 82.

Is 82 just the virtualization (SIE) support for 81?

--

Thanks,

David / dhildenb