[RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)

Jinjie Ruan via posted 22 patches 9 months, 1 week ago
Maintainers: Peter Maydell <peter.maydell@linaro.org>
There is a newer version of this series
[RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)
Posted by Jinjie Ruan via 9 months, 1 week ago
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>
---
 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
 MSR_i_SVCR      1101 0101 0000 0 011 0100 0 mask:2 imm:1 011 11111
 
 # MRS, MSR (register), SYS, SYSL. These are all essentially the
diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c
index ebaa7f00df..3686926ada 100644
--- a/target/arm/tcg/helper-a64.c
+++ b/target/arm/tcg/helper-a64.c
@@ -66,6 +66,30 @@ void HELPER(msr_i_spsel)(CPUARMState *env, uint32_t imm)
     update_spsel(env, imm);
 }
 
+static void allint_check(CPUARMState *env, uint32_t op,
+                       uint32_t imm, uintptr_t ra)
+{
+    /* ALLINT update to PSTATE. */
+    if (arm_current_el(env) == 0) {
+        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());
+    if (imm == 1) {
+        env->allint |= PSTATE_ALLINT;
+    } else {
+        env->allint &= ~PSTATE_ALLINT;
+    }
+    arm_rebuild_hflags(env);
+}
+
 static void daif_check(CPUARMState *env, uint32_t op,
                        uint32_t imm, uintptr_t ra)
 {
diff --git a/target/arm/tcg/helper-a64.h b/target/arm/tcg/helper-a64.h
index 575a5dab7d..3aec703d4a 100644
--- a/target/arm/tcg/helper-a64.h
+++ b/target/arm/tcg/helper-a64.h
@@ -22,6 +22,7 @@ DEF_HELPER_FLAGS_1(rbit64, TCG_CALL_NO_RWG_SE, i64, i64)
 DEF_HELPER_2(msr_i_spsel, void, env, i32)
 DEF_HELPER_2(msr_i_daifset, void, env, i32)
 DEF_HELPER_2(msr_i_daifclear, void, env, i32)
+DEF_HELPER_2(msr_i_allint, void, env, i32)
 DEF_HELPER_3(vfp_cmph_a64, i64, f16, f16, ptr)
 DEF_HELPER_3(vfp_cmpeh_a64, i64, f16, f16, ptr)
 DEF_HELPER_3(vfp_cmps_a64, i64, f32, f32, ptr)
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index 340265beb0..f1800f7c71 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -2036,6 +2036,16 @@ static bool trans_MSR_i_DAIFCLEAR(DisasContext *s, arg_i *a)
     return true;
 }
 
+static bool trans_MSR_i_ALLINT(DisasContext *s, arg_i *a)
+{
+    if (!dc_isar_feature(aa64_nmi, s) || s->current_el == 0) {
+        return false;
+    }
+    gen_helper_msr_i_allint(tcg_env, tcg_constant_i32(a->imm));
+    s->base.is_jmp = DISAS_TOO_MANY;
+    return true;
+}
+
 static bool trans_MSR_i_SVCR(DisasContext *s, arg_MSR_i_SVCR *a)
 {
     if (!dc_isar_feature(aa64_sme, s) || a->mask == 0) {
-- 
2.34.1
Re: [RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)
Posted by Richard Henderson 9 months, 1 week ago
On 2/21/24 03:08, 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>
> ---
>   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
>   MSR_i_SVCR      1101 0101 0000 0 011 0100 0 mask:2 imm:1 011 11111
>   
>   # MRS, MSR (register), SYS, SYSL. These are all essentially the
> diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c
> index ebaa7f00df..3686926ada 100644
> --- a/target/arm/tcg/helper-a64.c
> +++ b/target/arm/tcg/helper-a64.c
> @@ -66,6 +66,30 @@ void HELPER(msr_i_spsel)(CPUARMState *env, uint32_t imm)
>       update_spsel(env, imm);
>   }
>   
> +static void allint_check(CPUARMState *env, uint32_t op,
> +                       uint32_t imm, uintptr_t ra)
> +{
> +    /* ALLINT update to PSTATE. */
> +    if (arm_current_el(env) == 0) {
> +        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);
> +    }
> +}

A runtime check for EL0 is not necessary; you've already handled that in 
trans_MSR_i_ALLINT().  However, what *is* missing here is the test against TALLINT for EL1.

> +
> +void HELPER(msr_i_allint)(CPUARMState *env, uint32_t imm)
> +{
> +    allint_check(env, 0x8, imm, GETPC());
> +    if (imm == 1) {
> +        env->allint |= PSTATE_ALLINT;
> +    } else {
> +        env->allint &= ~PSTATE_ALLINT;
> +    }

I think you should not write an immediate-specific helper, but one which can also handle 
the variable "MSR allint, <xt>".  This is no more difficult than

void HELPER(msr_allint)(CPUARMState *env, target_ulong val)
{
     ... check ...
     env->pstate = (env->pstate & ~PSTATE_ALLINT) | (val & PSTATE_ALLINT);
}

> +    arm_rebuild_hflags(env);
> +}

allint does not affect hflags; no rebuild required.

> +static bool trans_MSR_i_ALLINT(DisasContext *s, arg_i *a)
> +{
> +    if (!dc_isar_feature(aa64_nmi, s) || s->current_el == 0) {
> +        return false;
> +    }
> +    gen_helper_msr_i_allint(tcg_env, tcg_constant_i32(a->imm));

You're passing all of #imm4, not #imm1, which meant the test in your msr_i_allint helper 
was wrong.

To work with the generalized helper above, this would be

     tcg_constant_tl((a->imm & 1) * PSTATE_ALLINT);


r~
Re: [RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)
Posted by Jinjie Ruan via 9 months, 1 week ago

On 2024/2/22 3:09, Richard Henderson wrote:
> On 2/21/24 03:08, 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>
>> ---
>>   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
>>   MSR_i_SVCR      1101 0101 0000 0 011 0100 0 mask:2 imm:1 011 11111
>>     # MRS, MSR (register), SYS, SYSL. These are all essentially the
>> diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c
>> index ebaa7f00df..3686926ada 100644
>> --- a/target/arm/tcg/helper-a64.c
>> +++ b/target/arm/tcg/helper-a64.c
>> @@ -66,6 +66,30 @@ void HELPER(msr_i_spsel)(CPUARMState *env, uint32_t
>> imm)
>>       update_spsel(env, imm);
>>   }
>>   +static void allint_check(CPUARMState *env, uint32_t op,
>> +                       uint32_t imm, uintptr_t ra)
>> +{
>> +    /* ALLINT update to PSTATE. */
>> +    if (arm_current_el(env) == 0) {
>> +        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);
>> +    }
>> +}
> 
> A runtime check for EL0 is not necessary; you've already handled that in
> trans_MSR_i_ALLINT().  However, what *is* missing here is the test
> against TALLINT for EL1.

Thank you! I'll fix it.

> 
>> +
>> +void HELPER(msr_i_allint)(CPUARMState *env, uint32_t imm)
>> +{
>> +    allint_check(env, 0x8, imm, GETPC());
>> +    if (imm == 1) {
>> +        env->allint |= PSTATE_ALLINT;
>> +    } else {
>> +        env->allint &= ~PSTATE_ALLINT;
>> +    }
> 
> I think you should not write an immediate-specific helper, but one which
> can also handle the variable "MSR allint, <xt>".  This is no more
> difficult than

The kernel patches now uses the immediate-specific helper only, so it is
necessary for test.

> 
> void HELPER(msr_allint)(CPUARMState *env, target_ulong val)
> {
>     ... check ...
>     env->pstate = (env->pstate & ~PSTATE_ALLINT) | (val & PSTATE_ALLINT);
> }
> 
>> +    arm_rebuild_hflags(env);
>> +}
> 
> allint does not affect hflags; no rebuild required.

Thank you! I'll fix it.

> 
>> +static bool trans_MSR_i_ALLINT(DisasContext *s, arg_i *a)
>> +{
>> +    if (!dc_isar_feature(aa64_nmi, s) || s->current_el == 0) {
>> +        return false;
>> +    }
>> +    gen_helper_msr_i_allint(tcg_env, tcg_constant_i32(a->imm));
> 
> You're passing all of #imm4, not #imm1, which meant the test in your
> msr_i_allint helper was wrong.

In fact, it's either 0 or 1 for CRm according to the arm manual, so it
is not necessary.

> 
> To work with the generalized helper above, this would be
> 
>     tcg_constant_tl((a->imm & 1) * PSTATE_ALLINT);
> 
> 
> r~

Re: [RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)
Posted by Richard Henderson 9 months, 1 week ago
On 2/21/24 09:09, Richard Henderson wrote:
> On 2/21/24 03:08, 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>
>> ---
>>   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
>>   MSR_i_SVCR      1101 0101 0000 0 011 0100 0 mask:2 imm:1 011 11111
>>   # MRS, MSR (register), SYS, SYSL. These are all essentially the
>> diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c
>> index ebaa7f00df..3686926ada 100644
>> --- a/target/arm/tcg/helper-a64.c
>> +++ b/target/arm/tcg/helper-a64.c
>> @@ -66,6 +66,30 @@ void HELPER(msr_i_spsel)(CPUARMState *env, uint32_t imm)
>>       update_spsel(env, imm);
>>   }
>> +static void allint_check(CPUARMState *env, uint32_t op,
>> +                       uint32_t imm, uintptr_t ra)
>> +{
>> +    /* ALLINT update to PSTATE. */
>> +    if (arm_current_el(env) == 0) {
>> +        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);
>> +    }
>> +}
> 
> A runtime check for EL0 is not necessary; you've already handled that in 
> trans_MSR_i_ALLINT().  However, what *is* missing here is the test against TALLINT for EL1.
> 
>> +
>> +void HELPER(msr_i_allint)(CPUARMState *env, uint32_t imm)
>> +{
>> +    allint_check(env, 0x8, imm, GETPC());
>> +    if (imm == 1) {
>> +        env->allint |= PSTATE_ALLINT;
>> +    } else {
>> +        env->allint &= ~PSTATE_ALLINT;
>> +    }
> 
> I think you should not write an immediate-specific helper, but one which can also handle 
> the variable "MSR allint, <xt>".  This is no more difficult than
> 
> void HELPER(msr_allint)(CPUARMState *env, target_ulong val)
> {
>      ... check ...
>      env->pstate = (env->pstate & ~PSTATE_ALLINT) | (val & PSTATE_ALLINT);
> }

Ho hum..  I just noticed that TALLINT only traps immediate write of 1, not also immediate 
write of 0.  So one helper for both MSR Xt and MSR imm is not practical.


r~

Re: [RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)
Posted by Richard Henderson 9 months, 1 week ago
On 2/21/24 10:41, Richard Henderson wrote:
> Ho hum..  I just noticed that TALLINT only traps immediate write of 1, not also immediate 
> write of 0.  So one helper for both MSR Xt and MSR imm is not practical.

Quick follow up to say that means you can do

static bool trans_MSR_i_ALLINT(DisasContext *s, arg_i *a)
{
     if (!dc_isar_feature(aa64_nmi, s)
         || s->current_el == 0
         || (a->imm & ~1)) {
         return false;
     }
     if (!a->imm) {
         clear_pstate_bits(PSTATE_ALLINT);
     } else if (arm_dc_feature(s, ARM_FEATURE_EL2) && s->current_el == 1) {
         /* Use helper for runtime check against HCRX_EL2.TALLINT. */
         gen_helper_msr_set_allint_el1(tcg_env);
     } else {
         set_pstate_bits(PSTATE_ALLINT);
     }
     return true;
}

Generate inline bit ops whenever TALLINT does not apply.
This also means the helper need not check current_el, because we've already done it here.


r~

Re: [RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)
Posted by Jinjie Ruan via 9 months, 1 week ago

On 2024/2/22 4:41, Richard Henderson wrote:
> On 2/21/24 09:09, Richard Henderson wrote:
>> On 2/21/24 03:08, 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>
>>> ---
>>>   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
>>>   MSR_i_SVCR      1101 0101 0000 0 011 0100 0 mask:2 imm:1 011 11111
>>>   # MRS, MSR (register), SYS, SYSL. These are all essentially the
>>> diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c
>>> index ebaa7f00df..3686926ada 100644
>>> --- a/target/arm/tcg/helper-a64.c
>>> +++ b/target/arm/tcg/helper-a64.c
>>> @@ -66,6 +66,30 @@ void HELPER(msr_i_spsel)(CPUARMState *env,
>>> uint32_t imm)
>>>       update_spsel(env, imm);
>>>   }
>>> +static void allint_check(CPUARMState *env, uint32_t op,
>>> +                       uint32_t imm, uintptr_t ra)
>>> +{
>>> +    /* ALLINT update to PSTATE. */
>>> +    if (arm_current_el(env) == 0) {
>>> +        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);
>>> +    }
>>> +}
>>
>> A runtime check for EL0 is not necessary; you've already handled that
>> in trans_MSR_i_ALLINT().  However, what *is* missing here is the test
>> against TALLINT for EL1.
>>
>>> +
>>> +void HELPER(msr_i_allint)(CPUARMState *env, uint32_t imm)
>>> +{
>>> +    allint_check(env, 0x8, imm, GETPC());
>>> +    if (imm == 1) {
>>> +        env->allint |= PSTATE_ALLINT;
>>> +    } else {
>>> +        env->allint &= ~PSTATE_ALLINT;
>>> +    }
>>
>> I think you should not write an immediate-specific helper, but one
>> which can also handle the variable "MSR allint, <xt>".  This is no
>> more difficult than
>>
>> void HELPER(msr_allint)(CPUARMState *env, target_ulong val)
>> {
>>      ... check ...
>>      env->pstate = (env->pstate & ~PSTATE_ALLINT) | (val &
>> PSTATE_ALLINT);
>> }
> 
> Ho hum..  I just noticed that TALLINT only traps immediate write of 1,
> not also immediate write of 0.  So one helper for both MSR Xt and MSR
> imm is not practical.

it is a real problem.

> 
> 
> r~

Re: [RFC PATCH v2 04/22] target/arm: Implement ALLINT MSR (immediate)
Posted by Richard Henderson 9 months, 1 week ago
On 2/21/24 09:09, Richard Henderson wrote:
>> +static bool trans_MSR_i_ALLINT(DisasContext *s, arg_i *a)
>> +{
>> +    if (!dc_isar_feature(aa64_nmi, s) || s->current_el == 0) {
>> +        return false;
>> +    }
>> +    gen_helper_msr_i_allint(tcg_env, tcg_constant_i32(a->imm));
> 
> You're passing all of #imm4, not #imm1, which meant the test in your msr_i_allint helper 
> was wrong.
> 
> To work with the generalized helper above, this would be
> 
>      tcg_constant_tl((a->imm & 1) * PSTATE_ALLINT);

Actually, I should have read further in the pseudocode -- (imm & 0xe) != 0 is undefined.


r~