Re: [PATCH v2 2/2] target/ppc: Check DEXCR on hash{st, chk} instructions

[Harsh Prateek Bora]

On 12/9/22 11:43, Nicholas Miehlbradt wrote:
> Adds checks to the hashst and hashchk instructions to only execute if
> enabled by the relevant aspect in the DEXCR and HDEXCR.
>
> This behaviour is guarded behind TARGET_PPC64 since Power10 is
> currently the only implementation which has the DEXCR.
>
> Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> Signed-off-by: Nicholas Miehlbradt <nicholas@linux.ibm.com>
> ---
>   target/ppc/excp_helper.c | 58 +++++++++++++++++++++++++++++-----------
>   1 file changed, 43 insertions(+), 15 deletions(-)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index 94adcb766b..add4d54ae7 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -2902,29 +2902,57 @@ static uint64_t hash_digest(uint64_t ra, uint64_t rb, 
> uint64_t key)
>       return stage1_h ^ stage1_l;
>   }
>   
> +static void do_hash(CPUPPCState *env, target_ulong ea, target_ulong ra,
> +                    target_ulong rb, uint64_t key, bool store)
> +{
> +    uint64_t calculated_hash = hash_digest(ra, rb, key), loaded_hash;
> +
> +    if (store) {
> +        cpu_stq_data_ra(env, ea, calculated_hash, GETPC());
> +    } else {
> +        loaded_hash = cpu_ldq_data_ra(env, ea, GETPC());
> +        if (loaded_hash != calculated_hash) {
> +            raise_exception_err_ra(env, POWERPC_EXCP_PROGRAM,
> +                POWERPC_EXCP_TRAP, GETPC());
> +        }
> +    }
> +}
> +
>   #include "qemu/guest-random.h"
>   
> -#define HELPER_HASH(op, key, store)                                           \
> +#ifdef TARGET_PPC64
> +#define HELPER_HASH(op, key, store, dexcr_aspect)                             \
>   void helper_##op(CPUPPCState *env, target_ulong ea, target_ulong ra,          
> \
>                    target_ulong rb)                                             
> \
>   {  

Conditional compilation could be contained within function, so that 
duplicate lines of code in each macro block could be avoided and would 
look simpler.

   \
> -    uint64_t calculated_hash = hash_digest(ra, rb, key), loaded_hash;         \
> -                                                                              \
> -    if (store) {                                                              \
> -        cpu_stq_data_ra(env, ea, calculated_hash, GETPC());                   \
> -    } else {                                                                  \
> -        loaded_hash = cpu_ldq_data_ra(env, ea, GETPC());                      \
> -        if (loaded_hash != calculated_hash) {                                 \
> -            raise_exception_err_ra(env, POWERPC_EXCP_PROGRAM,                 \
> -                POWERPC_EXCP_TRAP, GETPC());                                  \
> -        }                                                                     \
> +    if (env->msr & R_MSR_PR_MASK) {                                           \
> +        if (!(env->spr[SPR_DEXCR] & R_DEXCR_PRO_##dexcr_aspect##_MASK ||      \
> +            env->spr[SPR_HDEXCR] & R_HDEXCR_ENF_##dexcr_aspect##_MASK))       \
> +            return;                                                           \
> +    } else if (!(env->msr & R_MSR_HV_MASK)) {                                 \
> +        if (!(env->spr[SPR_DEXCR] & R_DEXCR_PNH_##dexcr_aspect##_MASK ||      \
> +            env->spr[SPR_HDEXCR] & R_HDEXCR_ENF_##dexcr_aspect##_MASK))       \
> +            return;                                                           \
> +    } else if (!(env->msr & R_MSR_S_MASK)) {                                  \
> +        if (!(env->spr[SPR_HDEXCR] & R_HDEXCR_HNU_##dexcr_aspect##_MASK))     \
> +            return;                                                           \
>       }                                                                         
> \
> +                                                                              \
> +    do_hash(env, ea, ra, rb, key, store);                                     \
> +}
> +#else
> +#define HELPER_HASH(op, key, store, dexcr_aspect)                             \
> +void helper_##op(CPUPPCState *env, target_ulong ea, target_ulong ra,          \
> +                 target_ulong rb)                                             \
> +{                                                                             \
> +    do_hash(env, ea, ra, rb, key, store);                                     \
>   }
> +#endif /* TARGET_PPC64 */
>   
> -HELPER_HASH(HASHST, env->spr[SPR_HASHKEYR], true)
> -HELPER_HASH(HASHCHK, env->spr[SPR_HASHKEYR], false)
> -HELPER_HASH(HASHSTP, env->spr[SPR_HASHPKEYR], true)
> -HELPER_HASH(HASHCHKP, env->spr[SPR_HASHPKEYR], false)
> +HELPER_HASH(HASHST, env->spr[SPR_HASHKEYR], true, NPHIE)
> +HELPER_HASH(HASHCHK, env->spr[SPR_HASHKEYR], false, NPHIE)
> +HELPER_HASH(HASHSTP, env->spr[SPR_HASHPKEYR], true, PHIE)
> +HELPER_HASH(HASHCHKP, env->spr[SPR_HASHPKEYR], false, PHIE)
>   #endif /* CONFIG_TCG */
>   
>   #if !defined(CONFIG_USER_ONLY)

Otherwise, looks good to me!

regards,
Harsh Prateek Bora