Re: [PATCH 2/3] target/riscv: Add dummy mcountinhibit CSR for priv spec v1.11 or higher

[Atish Patra]

On Wed, May 4, 2022 at 2:53 AM Frank Chang <frank.chang@sifive.com> wrote:
>
> Hi Anup,
>
> I found that Atish has already submitted a patch to implement the 
> mcountinhibit CSR:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg879349.html
>

Yeah. I think it depends on which series is merged first. The PMU
series actually uses mcountinhibit.
However, latest OpenSBI patches detect priv version v1.11 based on
mcountinhibit presence.
We need mcountinhibit support to test any v1.12 patches anyways.

If PMU patches are merged first, we don't need this patch.

> Regards,
> Frank Chang
>
> On Fri, Apr 29, 2022 at 11:44 PM Anup Patel <apatel@ventanamicro.com> wrote:
>>
>> The mcountinhibit CSR is mandatory for priv spec v1.11 or higher. For
>> implementation that don't want to implement can simply have a dummy
>> mcountinhibit which always zero.
>>
>> Fixes: a4b2fa433125 ("target/riscv: Introduce privilege version field in
>> the CSR ops.")
>> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
>> ---
>>  target/riscv/cpu_bits.h | 3 +++
>>  target/riscv/csr.c      | 2 ++
>>  2 files changed, 5 insertions(+)
>>
>> diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
>> index 4d04b20d06..4a55c6a709 100644
>> --- a/target/riscv/cpu_bits.h
>> +++ b/target/riscv/cpu_bits.h
>> @@ -159,6 +159,9 @@
>>  #define CSR_MTVEC           0x305
>>  #define CSR_MCOUNTEREN      0x306
>>
>> +/* Machine Counter Setup */
>> +#define CSR_MCOUNTINHIBIT   0x320
>> +
>>  /* 32-bit only */
>>  #define CSR_MSTATUSH        0x310
>>
>> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
>> index 2bf0a97196..e144ce7135 100644
>> --- a/target/riscv/csr.c
>> +++ b/target/riscv/csr.c
>> @@ -3391,6 +3391,8 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
>>      [CSR_MIE]         = { "mie",        any,   NULL,    NULL,    rmw_mie    
>>        },
>>      [CSR_MTVEC]       = { "mtvec",      any,   read_mtvec,       
>> write_mtvec       },
>>      [CSR_MCOUNTEREN]  = { "mcounteren", any,   read_mcounteren,  
>> write_mcounteren  },
>> +    [CSR_MCOUNTINHIBIT] = { "mcountinhibit", any, read_zero, write_ignore,
>> +                                             .min_priv_ver = 
>> PRIV_VERSION_1_11_0 },
>>
>>      [CSR_MSTATUSH]    = { "mstatush",   any32, read_mstatush,    
>> write_mstatush    },
>>
>> --
>> 2.34.1
>>
>>


-- 
Regards,
Atish