[2/6] target/riscv: add riscv,isa to named features

Further discussions after the introduction of rva22 support in QEMU
revealed that what we've been calling 'named features' are actually
regular extensions, with their respective riscv,isa DTs. This is
clarified in [1]. [2] is a bug tracker asking for the profile spec to be
less cryptic about it.

As far as QEMU goes we understand extensions as something that the user
can enable/disable in the command line. This isn't the case for named
features, so we'll have to reach a middle ground.

We'll keep our existing nomenclature 'named features' to refer to any
extension that the user can't control in the command line. We'll also do
the following:

- 'svade' and 'zic64b' flags are renamed to 'ext_svade' and
  'ext_zic64b'. 'ext_svade' and 'ext_zic64b' now have riscv,isa strings and
  priv_spec versions;

- skip name feature check in cpu_bump_multi_ext_priv_ver(). Now that
  named features have a riscv,isa and an entry in isa_edata_arr[] we
  don't need to gate the call to cpu_cfg_ext_get_min_version() anymore.

[1] https://github.com/riscv/riscv-profiles/issues/121
[2] https://github.com/riscv/riscv-profiles/issues/142

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/cpu.c         | 17 +++++++++++++----
 target/riscv/cpu_cfg.h     |  6 ++++--
 target/riscv/tcg/tcg-cpu.c | 16 ++++++----------
 3 files changed, 23 insertions(+), 16 deletions(-)

On Fri, Jan 26, 2024 at 6:55 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> Further discussions after the introduction of rva22 support in QEMU
> revealed that what we've been calling 'named features' are actually
> regular extensions, with their respective riscv,isa DTs. This is
> clarified in [1]. [2] is a bug tracker asking for the profile spec to be
> less cryptic about it.
>
> As far as QEMU goes we understand extensions as something that the user
> can enable/disable in the command line. This isn't the case for named
> features, so we'll have to reach a middle ground.
>
> We'll keep our existing nomenclature 'named features' to refer to any
> extension that the user can't control in the command line. We'll also do
> the following:
>
> - 'svade' and 'zic64b' flags are renamed to 'ext_svade' and
>   'ext_zic64b'. 'ext_svade' and 'ext_zic64b' now have riscv,isa strings and
>   priv_spec versions;
>
> - skip name feature check in cpu_bump_multi_ext_priv_ver(). Now that
>   named features have a riscv,isa and an entry in isa_edata_arr[] we
>   don't need to gate the call to cpu_cfg_ext_get_min_version() anymore.
>
> [1] https://github.com/riscv/riscv-profiles/issues/121
> [2] https://github.com/riscv/riscv-profiles/issues/142
>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/cpu.c         | 17 +++++++++++++----
>  target/riscv/cpu_cfg.h     |  6 ++++--
>  target/riscv/tcg/tcg-cpu.c | 16 ++++++----------
>  3 files changed, 23 insertions(+), 16 deletions(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 88e8cc8681..28d3cfa8ce 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -97,6 +97,7 @@ bool riscv_cpu_option_set(const char *optname)
>   * instead.
>   */
>  const RISCVIsaExtData isa_edata_arr[] = {
> +    ISA_EXT_DATA_ENTRY(zic64b, PRIV_VERSION_1_12_0, ext_zic64b),
>      ISA_EXT_DATA_ENTRY(zicbom, PRIV_VERSION_1_12_0, ext_zicbom),
>      ISA_EXT_DATA_ENTRY(zicbop, PRIV_VERSION_1_12_0, ext_zicbop),
>      ISA_EXT_DATA_ENTRY(zicboz, PRIV_VERSION_1_12_0, ext_zicboz),
> @@ -171,6 +172,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(ssaia, PRIV_VERSION_1_12_0, ext_ssaia),
>      ISA_EXT_DATA_ENTRY(sscofpmf, PRIV_VERSION_1_12_0, ext_sscofpmf),
>      ISA_EXT_DATA_ENTRY(sstc, PRIV_VERSION_1_12_0, ext_sstc),
> +    ISA_EXT_DATA_ENTRY(svade, PRIV_VERSION_1_11_0, ext_svade),
>      ISA_EXT_DATA_ENTRY(svadu, PRIV_VERSION_1_12_0, ext_svadu),
>      ISA_EXT_DATA_ENTRY(svinval, PRIV_VERSION_1_12_0, ext_svinval),
>      ISA_EXT_DATA_ENTRY(svnapot, PRIV_VERSION_1_12_0, ext_svnapot),
> @@ -1510,9 +1512,16 @@ const RISCVCPUMultiExtConfig riscv_cpu_experimental_exts[] = {
>      DEFINE_PROP_END_OF_LIST(),
>  };
>
> +/*
> + * 'Named features' is the name we give to extensions that we
> + * don't want to expose to users. They are either immutable
> + * (always enabled/disable) or they'll vary depending on
> + * the resulting CPU state. They have riscv,isa strings
> + * and priv_ver like regular extensions.
> + */
>  const RISCVCPUMultiExtConfig riscv_cpu_named_features[] = {
> -    MULTI_EXT_CFG_BOOL("svade", svade, true),
> -    MULTI_EXT_CFG_BOOL("zic64b", zic64b, true),
> +    MULTI_EXT_CFG_BOOL("svade", ext_svade, true),
> +    MULTI_EXT_CFG_BOOL("zic64b", ext_zic64b, true),
>
>      DEFINE_PROP_END_OF_LIST(),
>  };
> @@ -2130,7 +2139,7 @@ static RISCVCPUProfile RVA22U64 = {
>          CPU_CFG_OFFSET(ext_zicbop), CPU_CFG_OFFSET(ext_zicboz),
>
>          /* mandatory named features for this profile */
> -        CPU_CFG_OFFSET(zic64b),
> +        CPU_CFG_OFFSET(ext_zic64b),
>
>          RISCV_PROFILE_EXT_LIST_END
>      }
> @@ -2161,7 +2170,7 @@ static RISCVCPUProfile RVA22S64 = {
>          CPU_CFG_OFFSET(ext_svinval),
>
>          /* rva22s64 named features */
> -        CPU_CFG_OFFSET(svade),
> +        CPU_CFG_OFFSET(ext_svade),
>
>          RISCV_PROFILE_EXT_LIST_END
>      }
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index e241922f89..698f926ab1 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -117,13 +117,15 @@ struct RISCVCPUConfig {
>      bool ext_smepmp;
>      bool rvv_ta_all_1s;
>      bool rvv_ma_all_1s;
> -    bool svade;
> -    bool zic64b;
>
>      uint32_t mvendorid;
>      uint64_t marchid;
>      uint64_t mimpid;
>
> +    /* Named features  */
> +    bool ext_svade;
> +    bool ext_zic64b;
> +
>      /* Vendor-specific custom extensions */
>      bool ext_xtheadba;
>      bool ext_xtheadbb;
> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
> index 88f92d1c7d..90861cc065 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -197,12 +197,12 @@ static bool cpu_cfg_offset_is_named_feat(uint32_t ext_offset)
>  static void riscv_cpu_enable_named_feat(RISCVCPU *cpu, uint32_t feat_offset)
>  {
>      switch (feat_offset) {
> -    case CPU_CFG_OFFSET(zic64b):
> +    case CPU_CFG_OFFSET(ext_zic64b):
>          cpu->cfg.cbom_blocksize = 64;
>          cpu->cfg.cbop_blocksize = 64;
>          cpu->cfg.cboz_blocksize = 64;
>          break;
> -    case CPU_CFG_OFFSET(svade):
> +    case CPU_CFG_OFFSET(ext_svade):
>          cpu->cfg.ext_svadu = false;
>          break;
>      default:
> @@ -219,10 +219,6 @@ static void cpu_bump_multi_ext_priv_ver(CPURISCVState *env,
>          return;
>      }
>
> -    if (cpu_cfg_offset_is_named_feat(ext_offset)) {
> -        return;
> -    }
> -
>      ext_priv_ver = cpu_cfg_ext_get_min_version(ext_offset);
>
>      if (env->priv_ver < ext_priv_ver) {
> @@ -349,11 +345,11 @@ static void riscv_cpu_disable_priv_spec_isa_exts(RISCVCPU *cpu)
>
>  static void riscv_cpu_update_named_features(RISCVCPU *cpu)
>  {
> -    cpu->cfg.zic64b = cpu->cfg.cbom_blocksize == 64 &&
> -                      cpu->cfg.cbop_blocksize == 64 &&
> -                      cpu->cfg.cboz_blocksize == 64;
> +    cpu->cfg.ext_zic64b = cpu->cfg.cbom_blocksize == 64 &&
> +                          cpu->cfg.cbop_blocksize == 64 &&
> +                          cpu->cfg.cboz_blocksize == 64;
>
> -    cpu->cfg.svade = !cpu->cfg.ext_svadu;
> +    cpu->cfg.ext_svade = !cpu->cfg.ext_svadu;
>  }
>
>  static void riscv_cpu_validate_g(RISCVCPU *cpu)
> --
> 2.43.0
>
>