Re: [PATCH 3/3] target/riscv: Consider priv spec version when generating ISA string

[Anup Patel]

On Sat, Apr 30, 2022 at 8:39 AM Frank Chang <frank.chang@sifive.com> wrote:
>
> Hi Anup,
>
> If we want to limit the generated ISA string to/after a specific privilege 
> spec version.
> Shouldn't we also check the privilege spec version when these extensions are 
> enabled?
> Otherwise, it's possible that one extension is enabled,
> but the privilege spec version is smaller than the one in which the extension 
> is supported.
> (This is possible if user specifies the privileged spec version through the 
> command line.)
> The ISA string therefore won't include the enabled extension.

This patch is only a temporary fix for the sifive_u machine where I am
seeing some
of these new extensions available in ISA string.

We need a separate series to have the priv spec version influence
individual extension
enabling/disabling.

Regards,
Anup

>
> Regards,
> Frank Chang
>
>
> On Fri, Apr 29, 2022 at 11:49 PM Anup Patel <apatel@ventanamicro.com> wrote:
>>
>> Most of the multi-letter extensions (such as Svpbmt, Svnapot, Svinval,
>> etc) are only available after Priv spec v1.12 so ISA string generation
>> should check the minimum required priv spec version for all extensions.
>>
>> Fixes: a775398be2e ("target/riscv: Add isa extenstion strings to the
>> device tree")
>> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
>> ---
>>  target/riscv/cpu.c | 36 +++++++++++++++++++-----------------
>>  1 file changed, 19 insertions(+), 17 deletions(-)
>>
>> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
>> index 02ee7d45d8..d8c88b96bc 100644
>> --- a/target/riscv/cpu.c
>> +++ b/target/riscv/cpu.c
>> @@ -44,6 +44,7 @@ static const char riscv_single_letter_exts[] = 
>> "IEMAFDQCPVH";
>>  struct isa_ext_data {
>>      const char *name;
>>      bool enabled;
>> +    uint32_t min_priv_ver;
>>  };
>>
>>  const char * const riscv_int_regnames[] = {
>> @@ -974,7 +975,7 @@ static void riscv_cpu_class_init(ObjectClass *c, void 
>> *data)
>>      device_class_set_props(dc, riscv_cpu_properties);
>>  }
>>
>> -#define ISA_EDATA_ENTRY(name, prop) {#name, cpu->cfg.prop}
>> +#define ISA_EDATA_ENTRY(name, prop, priv) {#name, cpu->cfg.prop, priv}
>>
>>  static void riscv_isa_string_ext(RISCVCPU *cpu, char **isa_str, int 
>> max_str_len)
>>  {
>> @@ -1000,25 +1001,26 @@ static void riscv_isa_string_ext(RISCVCPU *cpu, char 
>> **isa_str, int max_str_len)
>>       *    extensions by an underscore.
>>       */
>>      struct isa_ext_data isa_edata_arr[] = {
>> -        ISA_EDATA_ENTRY(zfh, ext_zfh),
>> -        ISA_EDATA_ENTRY(zfhmin, ext_zfhmin),
>> -        ISA_EDATA_ENTRY(zfinx, ext_zfinx),
>> -        ISA_EDATA_ENTRY(zhinx, ext_zhinx),
>> -        ISA_EDATA_ENTRY(zhinxmin, ext_zhinxmin),
>> -        ISA_EDATA_ENTRY(zdinx, ext_zdinx),
>> -        ISA_EDATA_ENTRY(zba, ext_zba),
>> -        ISA_EDATA_ENTRY(zbb, ext_zbb),
>> -        ISA_EDATA_ENTRY(zbc, ext_zbc),
>> -        ISA_EDATA_ENTRY(zbs, ext_zbs),
>> -        ISA_EDATA_ENTRY(zve32f, ext_zve32f),
>> -        ISA_EDATA_ENTRY(zve64f, ext_zve64f),
>> -        ISA_EDATA_ENTRY(svinval, ext_svinval),
>> -        ISA_EDATA_ENTRY(svnapot, ext_svnapot),
>> -        ISA_EDATA_ENTRY(svpbmt, ext_svpbmt),
>> +        ISA_EDATA_ENTRY(zfh, ext_zfh, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zfhmin, ext_zfhmin, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zfinx, ext_zfinx, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zhinx, ext_zhinx, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zhinxmin, ext_zhinxmin, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zdinx, ext_zdinx, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zba, ext_zba, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zbb, ext_zbb, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zbc, ext_zbc, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zbs, ext_zbs, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zve32f, ext_zve32f, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(zve64f, ext_zve64f, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(svinval, ext_svinval, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(svnapot, ext_svnapot, PRIV_VERSION_1_12_0),
>> +        ISA_EDATA_ENTRY(svpbmt, ext_svpbmt, PRIV_VERSION_1_12_0),
>>      };
>>
>>      for (i = 0; i < ARRAY_SIZE(isa_edata_arr); i++) {
>> -        if (isa_edata_arr[i].enabled) {
>> +        if (isa_edata_arr[i].enabled &&
>> +            cpu->env.priv_ver >= isa_edata_arr[i].min_priv_ver) {
>>              new = g_strconcat(old, "_", isa_edata_arr[i].name, NULL);
>>              g_free(old);
>>              old = new;
>> --
>> 2.34.1
>>
>>