Re: [PATCH 2/3] target/arm: Honor HCR_EL2.TID1 trapping requirements

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

On Thu, Nov 28, 2019 at 04:17:17PM +0000, Marc Zyngier wrote:
> HCR_EL2.TID1 mandates that access from EL1 to REVIDR_EL1, AIDR_EL1
> (and their 32bit equivalents) as well as TCMTR, TLBTR are trapped
> to EL2. QEMU ignores it, naking it harder for a hypervisor to

Typo: "making it harder"


> virtualize the HW (though to be fair, no known hypervisor actually
> cares).
> 
> Do the right thing by trapping to EL2 if HCR_EL2.TID1 is set.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  target/arm/helper.c | 36 ++++++++++++++++++++++++++++++++----
>  1 file changed, 32 insertions(+), 4 deletions(-)
> 
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index 0b6887b100..9bff769692 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -1973,6 +1973,26 @@ static uint64_t isr_read(CPUARMState *env, const ARMCPRegInfo *ri)
>      return ret;
>  }
>  
> +static CPAccessResult access_aa64_tid1(CPUARMState *env, const ARMCPRegInfo *ri,
> +                                       bool isread)
> +{
> +    if (arm_hcr_el2_eff(env) & HCR_TID1) {
> +        return CP_ACCESS_TRAP_EL2;
> +    }

I think we need to check for EL1 here?

Otherwise:
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>

Cheers,
Edgar


> +
> +    return CP_ACCESS_OK;
> +}
> +
> +static CPAccessResult access_aa32_tid1(CPUARMState *env, const ARMCPRegInfo *ri,
> +                                       bool isread)
> +{
> +    if (arm_feature(env, ARM_FEATURE_V8)) {
> +        return access_aa64_tid1(env, ri, isread);
> +    }
> +
> +    return CP_ACCESS_OK;
> +}
> +
>  static const ARMCPRegInfo v7_cp_reginfo[] = {
>      /* the old v6 WFI, UNPREDICTABLE in v7 but we choose to NOP */
>      { .name = "NOP", .cp = 15, .crn = 7, .crm = 0, .opc1 = 0, .opc2 = 4,
> @@ -2136,7 +2156,9 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
>       */
>      { .name = "AIDR", .state = ARM_CP_STATE_BOTH,
>        .opc0 = 3, .opc1 = 1, .crn = 0, .crm = 0, .opc2 = 7,
> -      .access = PL1_R, .type = ARM_CP_CONST, .resetvalue = 0 },
> +      .access = PL1_R, .type = ARM_CP_CONST,
> +      .accessfn = access_aa64_tid1,
> +      .resetvalue = 0 },
>      /* Auxiliary fault status registers: these also are IMPDEF, and we
>       * choose to RAZ/WI for all cores.
>       */
> @@ -6732,7 +6754,9 @@ void register_cp_regs_for_features(ARMCPU *cpu)
>                .access = PL1_R, .resetvalue = cpu->midr },
>              { .name = "REVIDR_EL1", .state = ARM_CP_STATE_BOTH,
>                .opc0 = 3, .opc1 = 0, .crn = 0, .crm = 0, .opc2 = 6,
> -              .access = PL1_R, .type = ARM_CP_CONST, .resetvalue = cpu->revidr },
> +              .access = PL1_R,
> +              .accessfn = access_aa64_tid1,
> +              .type = ARM_CP_CONST, .resetvalue = cpu->revidr },
>              REGINFO_SENTINEL
>          };
>          ARMCPRegInfo id_cp_reginfo[] = {
> @@ -6747,14 +6771,18 @@ void register_cp_regs_for_features(ARMCPU *cpu)
>              /* TCMTR and TLBTR exist in v8 but have no 64-bit versions */
>              { .name = "TCMTR",
>                .cp = 15, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = 2,
> -              .access = PL1_R, .type = ARM_CP_CONST, .resetvalue = 0 },
> +              .access = PL1_R,
> +              .accessfn = access_aa32_tid1,
> +              .type = ARM_CP_CONST, .resetvalue = 0 },
>              REGINFO_SENTINEL
>          };
>          /* TLBTR is specific to VMSA */
>          ARMCPRegInfo id_tlbtr_reginfo = {
>                .name = "TLBTR",
>                .cp = 15, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = 3,
> -              .access = PL1_R, .type = ARM_CP_CONST, .resetvalue = 0,
> +              .access = PL1_R,
> +              .accessfn = access_aa32_tid1,
> +              .type = ARM_CP_CONST, .resetvalue = 0,
>          };
>          /* MPUIR is specific to PMSA V6+ */
>          ARMCPRegInfo id_mpuir_reginfo = {
> -- 
> 2.20.1
> 
>