Re: [PATCH v2 03/16] target/ppc: add exclusive user write function for MMCR0

[Daniel Henrique Barboza <danielhb413@gmail.com>]

On 8/25/21 1:37 AM, David Gibson wrote:
> On Tue, Aug 24, 2021 at 01:30:19PM -0300, Daniel Henrique Barboza wrote:
>> From: Gustavo Romero <gromero@linux.ibm.com>
>>
>> Similar to the previous patch, user write on some PowerPC
>> PMU regs, in this case, MMCR0, is limited. Create a new
>> function to handle that.
> 
> Ok.. ok, this fixes my concern on the previous patch.  Best to avoid
> the confusing interim step though.  I'm not sure there's a lot of use
> adding the general "group A" helper if you're going to replace them
> with more specific functions shortly afterwards.

Perhaps we should merge patches  2 and 3 together. I'll also take into
consideration that patch 15 will also add custom handling of more PMU
regs and, perhaps, drop patch 1 entirely since the only control left
for groupA will be MMCRA which can either be added separately or ignored
(the kernel EBB tests doesn't bother with MMCRA permissions).



Daniel

> 
>>
>> CC: Gustavo Romero <gustavo.romero@linaro.org>
>> Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
>> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
>> ---
>>   target/ppc/cpu_init.c  |  2 +-
>>   target/ppc/spr_tcg.h   |  1 +
>>   target/ppc/translate.c | 38 ++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 40 insertions(+), 1 deletion(-)
>>
>> diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
>> index 5510c3799f..860716da18 100644
>> --- a/target/ppc/cpu_init.c
>> +++ b/target/ppc/cpu_init.c
>> @@ -6868,7 +6868,7 @@ static void register_book3s_pmu_sup_sprs(CPUPPCState *env)
>>   static void register_book3s_pmu_user_sprs(CPUPPCState *env)
>>   {
>>       spr_register(env, SPR_POWER_UMMCR0, "UMMCR0",
>> -                 &spr_read_MMCR0_ureg, &spr_write_PMU_groupA_ureg,
>> +                 &spr_read_MMCR0_ureg, &spr_write_MMCR0_ureg,
>>                    &spr_read_ureg, &spr_write_ureg,
>>                    0x00000000);
>>       spr_register(env, SPR_POWER_UMMCR1, "UMMCR1",
>> diff --git a/target/ppc/spr_tcg.h b/target/ppc/spr_tcg.h
>> index 64ef2cd089..5c383dae3d 100644
>> --- a/target/ppc/spr_tcg.h
>> +++ b/target/ppc/spr_tcg.h
>> @@ -43,6 +43,7 @@ void spr_read_601_rtcu(DisasContext *ctx, int gprn, int sprn);
>>   void spr_read_spefscr(DisasContext *ctx, int gprn, int sprn);
>>   void spr_write_spefscr(DisasContext *ctx, int sprn, int gprn);
>>   void spr_write_PMU_groupA_ureg(DisasContext *ctx, int sprn, int gprn);
>> +void spr_write_MMCR0_ureg(DisasContext *ctx, int sprn, int gprn);
>>   
>>   #ifndef CONFIG_USER_ONLY
>>   void spr_write_generic32(DisasContext *ctx, int sprn, int gprn);
>> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
>> index ec4160378d..b48eec83e3 100644
>> --- a/target/ppc/translate.c
>> +++ b/target/ppc/translate.c
>> @@ -592,11 +592,49 @@ void spr_write_PMU_groupA_ureg(DisasContext *ctx, int sprn, int gprn)
>>       }
>>       spr_write_ureg(ctx, sprn, gprn);
>>   }
>> +
>> +void spr_write_MMCR0_ureg(DisasContext *ctx, int sprn, int gprn)
>> +{
>> +    TCGv t0, t1;
>> +
>> +    /*
>> +     * MMCR0 is a Group A SPR. The same write access control
>> +     * done in spr_write_PMU_groupA_ureg() applies.
>> +     */
>> +    if (ctx->pmcc_clear) {
>> +        gen_hvpriv_exception(ctx, POWERPC_EXCP_INVAL_SPR);
>> +        return;
>> +    }
>> +
>> +    t0 = tcg_temp_new();
>> +    t1 = tcg_temp_new();
>> +
>> +    /*
>> +     * Filter out all bits but FC, PMAO, and PMAE, according
>> +     * to ISA v3.1, in 10.4.4 Monitor Mode Control Register 0,
>> +     * fourth paragraph.
>> +     */
>> +    tcg_gen_andi_tl(t0, cpu_gpr[gprn],
>> +                    MMCR0_FC | MMCR0_PMAO | MMCR0_PMAE);
>> +    gen_load_spr(t1, SPR_POWER_MMCR0);
>> +    tcg_gen_andi_tl(t1, t1, ~(MMCR0_FC | MMCR0_PMAO | MMCR0_PMAE));
> 
> Since you're reusing them again here, definitely want a #define for
> this mask.
> 
>> +    /* Keep all other bits intact */
>> +    tcg_gen_or_tl(t1, t1, t0);
>> +    gen_store_spr(SPR_POWER_MMCR0, t1);
>> +
>> +    tcg_temp_free(t0);
>> +    tcg_temp_free(t1);
>> +}
>>   #else
>>   void spr_write_PMU_groupA_ureg(DisasContext *ctx, int sprn, int gprn)
>>   {
>>       spr_noaccess(ctx, gprn, sprn);
>>   }
>> +
>> +void spr_write_MMCR0_ureg(DisasContext *ctx, int sprn, int gprn)
>> +{
>> +    spr_noaccess(ctx, gprn, sprn);
>> +}
>>   #endif
>>   
>>   /* SPR common to all non-embedded PowerPC */
>