Re: [Qemu-devel] [PATCH v4 2/6] target-arm: Add CNTHCTL_EL2

[Peter Maydell]

On 5 June 2015 at 11:33, Edgar E. Iglesias <address@hidden> wrote:
> From: "Edgar E. Iglesias" <address@hidden>
>
> Adds control for trapping selected timer and counter accesses to EL2.
>
> Signed-off-by: Edgar E. Iglesias <address@hidden>
> ---
>  target-arm/cpu.h    |  1 +
>  target-arm/helper.c | 30 ++++++++++++++++++++++++++++--
>  2 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index 1a66aa4..f39c32b 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -355,6 +355,7 @@ typedef struct CPUARMState {
>          };
>          uint64_t c14_cntfrq; /* Counter Frequency register */
>          uint64_t c14_cntkctl; /* Timer Control register */
> +        uint32_t cnthctl_el2; /* Counter/Timer Hyp Control register */
>          uint64_t cntvoff_el2; /* Counter Virtual Offset register */
>          ARMGenericTimer c14_timer[NUM_GTIMERS];
>          uint32_t c15_cpar; /* XScale Coprocessor Access Register */
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 7901da1..1795e5f 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -1153,8 +1153,17 @@ static CPAccessResult gt_cntfrq_access(CPUARMState 
> *env, const ARMCPRegInfo *ri)
>
>  static CPAccessResult gt_counter_access(CPUARMState *env, int timeridx)
>  {
> +    unsigned int cur_el = arm_current_el(env);
> +    bool secure = arm_is_secure(env);
> +
> +    if (arm_feature(env, ARM_FEATURE_EL2) &&
> +        timeridx == GTIMER_PHYS && !secure && cur_el < 2 &&
> +        !extract32(env->cp15.cnthctl_el2, 0, 1)) {
> +        return CP_ACCESS_TRAP_EL2;
> +    }

The CNTKCTL controls take precedence over the CNTHCTL ones, so
this check needs to go below the existing one.

> +
>      /* CNT[PV]CT: not visible from PL0 if ELO[PV]CTEN is zero */
> -    if (arm_current_el(env) == 0 &&
> +    if (cur_el == 0 &&
>          !extract32(env->cp15.c14_cntkctl, timeridx, 1)) {
>          return CP_ACCESS_TRAP;
>      }
> @@ -1163,10 +1172,20 @@ static CPAccessResult gt_counter_access(CPUARMState 
> *env, int timeridx)
>
>  static CPAccessResult gt_timer_access(CPUARMState *env, int timeridx)
>  {
> +    unsigned int cur_el = arm_current_el(env);
> +    bool secure = arm_is_secure(env);
> +
> +    if (arm_feature(env, ARM_FEATURE_EL2)) {
> +        if (timeridx == GTIMER_PHYS && !secure && cur_el < 2 &&
> +            !extract32(env->cp15.cnthctl_el2, 1, 1)) {
> +            return CP_ACCESS_TRAP_EL2;
> +        }
> +    }

Wrong order again.

> +
>      /* CNT[PV]_CVAL, CNT[PV]_CTL, CNT[PV]_TVAL: not visible from PL0 if
>       * EL0[PV]TEN is zero.
>       */
> -    if (arm_current_el(env) == 0 &&
> +    if (cur_el == 0 &&
>          !extract32(env->cp15.c14_cntkctl, 9 - timeridx, 1)) {
>          return CP_ACCESS_TRAP;
>      }
> @@ -2566,6 +2585,9 @@ static const ARMCPRegInfo el3_no_el2_cp_reginfo[] = {
>      { .name = "HTTBR", .cp = 15, .opc1 = 4, .crm = 2,
>        .access = PL2_RW, .type = ARM_CP_64BIT | ARM_CP_CONST,
>        .resetvalue = 0 },
> +    { .name = "CNTHCTL_EL2", .state = ARM_CP_STATE_BOTH,
> +      .opc0 = 3, .opc1 = 4, .crn = 14, .crm = 1, .opc2 = 0,
> +      .access = PL2_RW, .type = ARM_CP_CONST, .resetvalue = 0 },
>      { .name = "CNTVOFF_EL2", .state = ARM_CP_STATE_AA64,
>        .opc0 = 3, .opc1 = 4, .crn = 14, .crm = 0, .opc2 = 3,
>        .access = PL2_RW, .type = ARM_CP_CONST, .resetvalue = 0 },
> @@ -2685,6 +2707,10 @@ static const ARMCPRegInfo el2_cp_reginfo[] = {
>        .type = ARM_CP_NO_RAW, .access = PL2_W,
>        .writefn = tlbi_aa64_vaa_write },
>  #ifndef CONFIG_USER_ONLY
> +    { .name = "CNTHCTL_EL2", .state = ARM_CP_STATE_BOTH,
> +      .opc0 = 3, .opc1 = 4, .crn = 14, .crm = 1, .opc2 = 0,
> +      .access = PL2_RW, .resetvalue = 3,

Why 3? The ARM ARM says the resetvalue is IMPDEF and might
be UNKNOWN.

> +      .fieldoffset = offsetof(CPUARMState, cp15.cnthctl_el2) },
>      { .name = "CNTVOFF_EL2", .state = ARM_CP_STATE_AA64,
>        .opc0 = 3, .opc1 = 4, .crn = 14, .crm = 0, .opc2 = 3,
>        .access = PL2_RW, .type = ARM_CP_IO, .resetvalue = 0,
> --
> 1.9.1
>

thanks
-- PMM