Re: [PATCH v2 21/35] target/riscv: Add hypvervisor trap support

[Palmer Dabbelt]

On Fri, 31 Jan 2020 17:02:30 PST (-0800), Alistair Francis wrote:
> Signed-off-by: Alistair Francis <address@hidden>
> ---
>  target/riscv/cpu_helper.c | 69 +++++++++++++++++++++++++++++++++------
>  1 file changed, 59 insertions(+), 10 deletions(-)
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 98017df33b..e7728cb0ca 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -639,6 +639,8 @@ void riscv_cpu_do_interrupt(CPUState *cs)
>
>      RISCVCPU *cpu = RISCV_CPU(cs);
>      CPURISCVState *env = &cpu->env;
> +    bool force_hs_execp = riscv_cpu_force_hs_excep_enabled(env);
> +    target_ulong s;
>
>      /* cs->exception is 32-bits wide unlike mcause which is XLEN-bits wide
>       * so we mask off the MSB and separate into trap type and cause.
> @@ -648,19 +650,14 @@ void riscv_cpu_do_interrupt(CPUState *cs)
>      target_ulong deleg = async ? env->mideleg : env->medeleg;
>      target_ulong tval = 0;
>
> -    static const int ecall_cause_map[] = {
> -        [PRV_U] = RISCV_EXCP_U_ECALL,
> -        [PRV_S] = RISCV_EXCP_S_ECALL,
> -        [PRV_H] = RISCV_EXCP_VS_ECALL,
> -        [PRV_M] = RISCV_EXCP_M_ECALL
> -    };
> -
>      if (!async) {
>          /* set tval to badaddr for traps with address information */
>          switch (cause) {
>          case RISCV_EXCP_INST_GUEST_PAGE_FAULT:
>          case RISCV_EXCP_LOAD_GUEST_ACCESS_FAULT:
>          case RISCV_EXCP_STORE_GUEST_AMO_ACCESS_FAULT:
> +            force_hs_execp = true;
> +            /* fallthrough */
>          case RISCV_EXCP_INST_ADDR_MIS:
>          case RISCV_EXCP_INST_ACCESS_FAULT:
>          case RISCV_EXCP_LOAD_ADDR_MIS:
> @@ -678,7 +675,16 @@ void riscv_cpu_do_interrupt(CPUState *cs)
>          /* ecall is dispatched as one cause so translate based on mode */
>          if (cause == RISCV_EXCP_U_ECALL) {
>              assert(env->priv <= 3);
> -            cause = ecall_cause_map[env->priv];
> +
> +            if (env->priv == PRV_M) {
> +                cause = RISCV_EXCP_M_ECALL;
> +            } else if (env->priv == PRV_S && riscv_cpu_virt_enabled(env)) {
> +                cause = RISCV_EXCP_VS_ECALL;
> +            } else if (env->priv == PRV_S && !riscv_cpu_virt_enabled(env)) {
> +                cause = RISCV_EXCP_S_ECALL;
> +            } else if (env->priv == PRV_U) {
> +                cause = RISCV_EXCP_U_ECALL;
> +            }
>          }
>      }
>
> @@ -688,7 +694,36 @@ void riscv_cpu_do_interrupt(CPUState *cs)
>      if (env->priv <= PRV_S &&
>              cause < TARGET_LONG_BITS && ((deleg >> cause) & 1)) {
>          /* handle the trap in S-mode */
> -        target_ulong s = env->mstatus;
> +        if (riscv_has_ext(env, RVH)) {
> +            target_ulong hdeleg = async ? env->hideleg : env->hedeleg;
> +
> +            if (riscv_cpu_virt_enabled(env) && ((hdeleg >> cause) & 1) &&
> +                !force_hs_execp) {
> +                /* Trap to VS mode */
> +            } else if (riscv_cpu_virt_enabled(env)) {
> +                /* Trap into HS mode, from virt */
> +                riscv_cpu_swap_hypervisor_regs(env);
> +                env->hstatus = set_field(env->hstatus, HSTATUS_SP2V,
> +                                         get_field(env->hstatus, HSTATUS_SPV));
> +                env->hstatus = set_field(env->hstatus, HSTATUS_SP2P,
> +                                         get_field(env->mstatus, SSTATUS_SPP));
> +                env->hstatus = set_field(env->hstatus, HSTATUS_SPV,
> +                                         riscv_cpu_virt_enabled(env));
> +
> +                riscv_cpu_set_virt_enabled(env, 0);
> +                riscv_cpu_set_force_hs_excep(env, 0);
> +            } else {
> +                /* Trap into HS mode */
> +                env->hstatus = set_field(env->hstatus, HSTATUS_SP2V,
> +                                         get_field(env->hstatus, HSTATUS_SPV));
> +                env->hstatus = set_field(env->hstatus, HSTATUS_SP2P,
> +                                         get_field(env->mstatus, SSTATUS_SPP));
> +                env->hstatus = set_field(env->hstatus, HSTATUS_SPV,
> +                                         riscv_cpu_virt_enabled(env));
> +            }
> +        }
> +
> +        s = env->mstatus;
>          s = set_field(s, MSTATUS_SPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
>              get_field(s, MSTATUS_SIE) : get_field(s, MSTATUS_UIE << 
> env->priv));
>          s = set_field(s, MSTATUS_SPP, env->priv);
> @@ -702,7 +737,21 @@ void riscv_cpu_do_interrupt(CPUState *cs)
>          riscv_cpu_set_mode(env, PRV_S);
>      } else {
>          /* handle the trap in M-mode */
> -        target_ulong s = env->mstatus;
> +        if (riscv_has_ext(env, RVH)) {
> +            if (riscv_cpu_virt_enabled(env)) {
> +                riscv_cpu_swap_hypervisor_regs(env);
> +            }
> +            env->mstatus = set_field(env->mstatus, MSTATUS_MPV,
> +                                      riscv_cpu_virt_enabled(env));
> +            env->mstatus = set_field(env->mstatus, MSTATUS_MTL,
> +                                      riscv_cpu_force_hs_excep_enabled(env));
> +
> +            /* Trapping to M mode, virt is disabled */
> +            riscv_cpu_set_virt_enabled(env, 0);
> +            riscv_cpu_set_force_hs_excep(env, 0);
> +        }
> +
> +        s = env->mstatus;
>          s = set_field(s, MSTATUS_MPIE, env->priv_ver >= PRIV_VERSION_1_10_0 ?
>              get_field(s, MSTATUS_MIE) : get_field(s, MSTATUS_UIE << 
> env->priv));
>          s = set_field(s, MSTATUS_MPP, env->priv);

Reviewed-by: Palmer Dabbelt <address@hidden>