Re: [Qemu-devel] [PATCH v1 13/16] target-arm: A64: Emulate the HVC insn

["Alex Bennée" <alex.bennee@linaro.org>]

Edgar E. Iglesias writes:

> From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
>
> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> ---
>  target-arm/cpu.h           |  7 ++-----
>  target-arm/helper-a64.c    |  1 +
>  target-arm/helper.c        | 39 +++++++++++++++++++++++++++++++++++++++
>  target-arm/helper.h        |  1 +
>  target-arm/internals.h     |  6 ++++++
>  target-arm/op_helper.c     | 21 +++++++++++++++++++++
>  target-arm/translate-a64.c | 21 ++++++++++++++++-----
>  7 files changed, 86 insertions(+), 10 deletions(-)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index 66c58bd..1a26ed4 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -51,6 +51,7 @@
>  #define EXCP_EXCEPTION_EXIT  8   /* Return from v7M exception.  */
>  #define EXCP_KERNEL_TRAP     9   /* Jumped to kernel code page.  */
>  #define EXCP_STREX          10
> +#define EXCP_HVC            11   /* HyperVisor Call */
>  
>  #define ARMV7M_EXCP_RESET   1
>  #define ARMV7M_EXCP_NMI     2
> @@ -715,11 +716,7 @@ static inline bool arm_el_is_aa64(CPUARMState *env, int el)
>  }
>  
>  void arm_cpu_list(FILE *f, fprintf_function cpu_fprintf);
> -static inline unsigned int arm_excp_target_el(CPUState *cs,
> -                                              unsigned int excp_idx)
> -{
> -    return 1;
> -}
> +unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx);

If the earlier commit had added this in the final place to start with
the functional diff would be clearer (although it's easy to eyeball in
this case).

>  
>  /* Interface between CPU and Interrupt controller.  */
>  void armv7m_nvic_set_pending(void *opaque, int irq);
> diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
> index c91005f..974fa66 100644
> --- a/target-arm/helper-a64.c
> +++ b/target-arm/helper-a64.c
> @@ -475,6 +475,7 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
>      case EXCP_BKPT:
>      case EXCP_UDEF:
>      case EXCP_SWI:
> +    case EXCP_HVC:
>          env->cp15.esr_el[new_el] = env->exception.syndrome;
>          break;
>      case EXCP_IRQ:
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index b760748..5b2070c 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -3208,6 +3208,11 @@ uint32_t HELPER(get_r13_banked)(CPUARMState *env, uint32_t mode)
>      return 0;
>  }
>  
> +unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
> +{
> +    return 1;
> +}
> +
>  #else
>  
>  /* Map CPU modes onto saved register banks.  */
> @@ -3263,6 +3268,40 @@ void switch_mode(CPUARMState *env, int mode)
>      env->spsr = env->banked_spsr[i];
>  }
>  
> +/*
> + * Determine the target EL for a given exception type.
> + */
> +unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
> +{
> +    CPUARMState *env = cs->env_ptr;
> +    unsigned int cur_el = arm_current_pl(env);
> +    unsigned int target_el = 1;
> +    bool route_to_el2 = false;
> +    /* FIXME: Use actual secure state.  */
> +    bool secure = false;

Should this be here?

<snip>
>  static inline void arm_log_exception(int idx)
> @@ -204,6 +205,11 @@ static inline uint32_t syn_aa64_svc(uint32_t imm16)
>      return (EC_AA64_SVC << ARM_EL_EC_SHIFT) | ARM_EL_IL | (imm16 & 0xffff);
>  }
>  
> +static inline uint32_t syn_aa64_hvc(uint32_t imm16)
> +{
> +    return (EC_AA64_HVC << ARM_EL_EC_SHIFT) | ARM_EL_IL | (imm16 & 0xffff);
> +}

The mask seems superfluous (as it is for arm_log_exception)

> +
>  static inline uint32_t syn_aa32_svc(uint32_t imm16, bool is_thumb)
>  {
>      return (EC_AA32_SVC << ARM_EL_EC_SHIFT) | (imm16 & 0xffff)
> diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> index 581dc09..6bf34b0 100644
> --- a/target-arm/op_helper.c
> +++ b/target-arm/op_helper.c
> @@ -384,6 +384,27 @@ void HELPER(msr_i_pstate)(CPUARMState *env, uint32_t op, uint32_t imm)
>      }
>  }
>  
> +void HELPER(hvc)(CPUARMState *env, uint32_t syndrome)
> +{
> +    bool udef;
> +
> +    /* We've already checked that EL2 exists at translation time.
> +     * EL3.HCE has priority over EL2.HCD.
> +     */
> +    if (arm_feature(env, ARM_FEATURE_EL3)) {
> +        udef = !(env->cp15.scr_el3 & SCR_HCE);
> +    } else {
> +        udef = env->cp15.hcr_el2 & HCR_HCD;
> +    }
> +
> +    if (udef) {
> +        env->exception.syndrome = syn_uncategorized();
> +        raise_exception(env, EXCP_UDEF);
> +    }
> +    env->exception.syndrome = syndrome;
> +    raise_exception(env, EXCP_HVC);
> +}
> +
>  void HELPER(exception_return)(CPUARMState *env)
>  {
>      int cur_el = arm_current_pl(env);
> diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
> index 9f964df..3981ee1 100644
> --- a/target-arm/translate-a64.c
> +++ b/target-arm/translate-a64.c
> @@ -1433,17 +1433,28 @@ static void disas_exc(DisasContext *s, uint32_t insn)
>      int opc = extract32(insn, 21, 3);
>      int op2_ll = extract32(insn, 0, 5);
>      int imm16 = extract32(insn, 5, 16);
> +    TCGv_i32 tmp;
>  
>      switch (opc) {
>      case 0:
> -        /* SVC, HVC, SMC; since we don't support the Virtualization
> -         * or TrustZone extensions these all UNDEF except SVC.
> -         */
> -        if (op2_ll != 1) {
> +        switch (op2_ll) {
> +        case 1:
> +            gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
> +            break;
> +        case 2:
> +            if (!arm_dc_feature(s, ARM_FEATURE_EL2) || s->current_pl == 0) {
> +                unallocated_encoding(s);
> +                break;
> +            }
> +            tmp = tcg_const_i32(syn_aa64_hvc(imm16));
> +            gen_a64_set_pc_im(s->pc);
> +            gen_helper_hvc(cpu_env, tmp);
> +            tcg_temp_free_i32(tmp);
> +            break;
> +        default:
>              unallocated_encoding(s);
>              break;
>          }
> -        gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
>          break;
>      case 1:
>          if (op2_ll != 0) {

-- 
Alex Bennée