Re: [Qemu-devel] [PATCH v3 22/23] target/ppc: Use qemu_guest_getrandom for DARN

[David Gibson]

On Thu, Mar 14, 2019 at 08:26:28PM -0700, Richard Henderson wrote:
> We now have an interface for guest visible random numbers.
> 
> Cc: address@hidden
> Cc: David Gibson <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>

Acked-by: David Gibson <address@hidden>

Do you want me to take this through my tree?

> ---
>  target/ppc/int_helper.c | 38 +++++++++++++++++++++++++++-----------
>  1 file changed, 27 insertions(+), 11 deletions(-)
> 
> diff --git a/target/ppc/int_helper.c b/target/ppc/int_helper.c
> index 162add561e..c26531e598 100644
> --- a/target/ppc/int_helper.c
> +++ b/target/ppc/int_helper.c
> @@ -23,6 +23,8 @@
>  #include "exec/helper-proto.h"
>  #include "crypto/aes.h"
>  #include "fpu/softfloat.h"
> +#include "qapi/error.h"
> +#include "qemu/guest-random.h"
>  
>  #include "helper_regs.h"
>  
> /*****************************************************************************/
> @@ -156,25 +158,39 @@ uint32_t helper_cmpeqb(target_ulong ra, target_ulong rb)
>  #undef haszero
>  #undef hasvalue
>  
> -/* Return invalid random number.
> - *
> - * FIXME: Add rng backend or other mechanism to get cryptographically 
> suitable
> - * random number
> - */
>  target_ulong helper_darn32(void)
>  {
> -    return -1;
> +    Error *err = NULL;
> +    uint32_t ret;
> +
> +    if (qemu_guest_getrandom(&ret, 4, &err) < 0) {
> +        qemu_log_mask(LOG_UNIMP, "darn: Crypto failure: %s",
> +                      error_get_pretty(err));
> +        error_free(err);
> +        return -1;
> +    }
> +
> +    return ret;
>  }
>  
>  target_ulong helper_darn64(void)
>  {
> -    return -1;
> +    Error *err = NULL;
> +    uint64_t ret;
> +
> +    do {
> +        if (qemu_guest_getrandom(&ret, 8, &err) < 0) {
> +            qemu_log_mask(LOG_UNIMP, "darn: Crypto failure: %s",
> +                          error_get_pretty(err));
> +            error_free(err);
> +            return -1;
> +        }
> +        /* Since -1 is the error condition, try again for that case.  */
> +    } while (unlikely(ret == -1));
> +
> +    return ret;
>  }
>  
> -#endif
> -
> -#if defined(TARGET_PPC64)
> -
>  uint64_t helper_bpermd(uint64_t rs, uint64_t rb)
>  {
>      int i;

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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