Re: [RFC PATCH v3 04/21] target/arm: Implement ALLINT MSR (immediate)

[Jinjie Ruan]

On 2024/2/24 3:03, Richard Henderson wrote:
> On 2/23/24 00:32, Jinjie Ruan via wrote:
>> Add ALLINT MSR (immediate) to decodetree. And the EL0 check is necessary
>> to ALLINT. Avoid the unconditional write to pc and use raise_exception_ra
>> to unwind.
>>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>> v3:
>> - Remove EL0 check in allint_check().
>> - Add TALLINT check for EL1 in allint_check().
>> - Remove unnecessarily arm_rebuild_hflags() in msr_i_allint helper.
>> ---
>>   target/arm/tcg/a64.decode      |  1 +
>>   target/arm/tcg/helper-a64.c    | 24 ++++++++++++++++++++++++
>>   target/arm/tcg/helper-a64.h    |  1 +
>>   target/arm/tcg/translate-a64.c | 10 ++++++++++
>>   4 files changed, 36 insertions(+)
>>
>> diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
>> index 8a20dce3c8..3588080024 100644
>> --- a/target/arm/tcg/a64.decode
>> +++ b/target/arm/tcg/a64.decode
>> @@ -207,6 +207,7 @@ MSR_i_DIT       1101 0101 0000 0 011 0100 .... 010
>> 11111 @msr_i
>>   MSR_i_TCO       1101 0101 0000 0 011 0100 .... 100 11111 @msr_i
>>   MSR_i_DAIFSET   1101 0101 0000 0 011 0100 .... 110 11111 @msr_i
>>   MSR_i_DAIFCLEAR 1101 0101 0000 0 011 0100 .... 111 11111 @msr_i
>> +MSR_i_ALLINT    1101 0101 0000 0 001 0100 .... 000 11111 @msr_i
> 
> Decode is incorrect either here, or in trans_MSR_i_ALLINT, because CRm
> != '000x' is UNDEFINED.
> 
> MSR_i_ALLINT    1101 0101 0000 0 001 0100 000 imm:1 000 11111
> 
> is perhaps the clearest implementation.
> 
>> +static void allint_check(CPUARMState *env, uint32_t op,
>> +                       uint32_t imm, uintptr_t ra)
>> +{
>> +    /* ALLINT update to PSTATE. */
>> +    if (arm_current_el(env) == 1 && arm_is_el2_enabled(env) &&
>> +        (arm_hcrx_el2_eff(env) & HCRX_TALLINT)) {
>> +        raise_exception_ra(env, EXCP_UDEF,
>> +                           syn_aa64_sysregtrap(0, extract32(op, 0, 3),
>> +                                               extract32(op, 3, 3), 4,
>> +                                               imm, 0x1f, 0),
>> +                           exception_target_el(env), ra);
>> +    }
>> +}
>> +
>> +void HELPER(msr_i_allint)(CPUARMState *env, uint32_t imm)
>> +{
>> +    allint_check(env, 0x8, imm, GETPC());
> 
> As previously noted, the check for MSR_i only applies to imm==1, not 0.

Sorry! The hardware manual I looked at didn't say this.

> 
> As previously noted, with ALLINT in env->pstate, you can implement this
> completely inline for EL[23], or EL1 with imm==0.
> 
> No point in passing in "op" and extracting, because you know exactly
> what the value should be for all MSR ALLINT.
> 
> 
> r~