diff mbox series

[v2,2/3] target/riscv/cpu.c: create flag for ziccrse

Message ID 20250221141834.626722-3-dbarboza@ventanamicro.com (mailing list archive)
State New
Headers show
Series target/riscv/kvm: update to Linux 6.14-rc3 | expand

Commit Message

Daniel Henrique Barboza Feb. 21, 2025, 2:18 p.m. UTC
At this moment ziccrse is a TCG always enabled named feature for
priv_ver > 1.11 that has no exclusive flag. In the next patch we'll make
the KVM driver update ziccrse as well, turning it on/off depending on
host settings, but for that we'll need an ext_ziccrse flag in the CPU
state.

Create an exclusive flag for it like we do with other named features.
As with any named features we already have, it won't be exposed to
users. TCG will keep the same restiction for it (always enabled if
has_priv_1_11 is true) and KVM will be free to turn it on/off as
required.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/cpu.c         | 3 ++-
 target/riscv/cpu_cfg.h     | 3 +++
 target/riscv/tcg/tcg-cpu.c | 2 ++
 3 files changed, 7 insertions(+), 1 deletion(-)

Comments

Andrew Jones Feb. 21, 2025, 3:11 p.m. UTC | #1
On Fri, Feb 21, 2025 at 11:18:33AM -0300, Daniel Henrique Barboza wrote:
> At this moment ziccrse is a TCG always enabled named feature for
> priv_ver > 1.11 that has no exclusive flag. In the next patch we'll make
> the KVM driver update ziccrse as well, turning it on/off depending on
> host settings, but for that we'll need an ext_ziccrse flag in the CPU
> state.
> 
> Create an exclusive flag for it like we do with other named features.
> As with any named features we already have, it won't be exposed to
> users. TCG will keep the same restiction for it (always enabled if
> has_priv_1_11 is true) and KVM will be free to turn it on/off as
> required.

Reading this as "KVM can choose" makes it sound wrong, since KVM can't
choose. However, KVM will turn it on/off depending on whether this
extension is/isn't present. So reading it as "TCG always has it on, but
KVM will turn it off when the extension isn't available", makes more
sense.

> 
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/cpu.c         | 3 ++-
>  target/riscv/cpu_cfg.h     | 3 +++
>  target/riscv/tcg/tcg-cpu.c | 2 ++
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 522d6584e4..fc4632ce36 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -105,7 +105,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(ziccamoa, PRIV_VERSION_1_11_0, has_priv_1_11),
>      ISA_EXT_DATA_ENTRY(ziccif, PRIV_VERSION_1_11_0, has_priv_1_11),
>      ISA_EXT_DATA_ENTRY(zicclsm, PRIV_VERSION_1_11_0, has_priv_1_11),
> -    ISA_EXT_DATA_ENTRY(ziccrse, PRIV_VERSION_1_11_0, has_priv_1_11),
> +    ISA_EXT_DATA_ENTRY(ziccrse, PRIV_VERSION_1_11_0, ext_ziccrse),
>      ISA_EXT_DATA_ENTRY(zicfilp, PRIV_VERSION_1_12_0, ext_zicfilp),
>      ISA_EXT_DATA_ENTRY(zicfiss, PRIV_VERSION_1_13_0, ext_zicfiss),
>      ISA_EXT_DATA_ENTRY(zicond, PRIV_VERSION_1_12_0, ext_zicond),
> @@ -1749,6 +1749,7 @@ const RISCVCPUMultiExtConfig riscv_cpu_named_features[] = {
>      MULTI_EXT_CFG_BOOL("zic64b", ext_zic64b, true),
>      MULTI_EXT_CFG_BOOL("ssstateen", ext_ssstateen, true),
>      MULTI_EXT_CFG_BOOL("sha", ext_sha, true),
> +    MULTI_EXT_CFG_BOOL("ziccrse", ext_ziccrse, true),
>  
>      { },
>  };
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index 3f3c1118c0..8a843482cc 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -166,6 +166,9 @@ struct RISCVCPUConfig {
>      bool has_priv_1_12;
>      bool has_priv_1_11;
>  
> +    /* Always enabled for TCG if has_priv_1_11 */
> +    bool ext_ziccrse;
> +
>      /* 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 ea8d77d06a..c93612b1da 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -360,6 +360,8 @@ static void riscv_cpu_update_named_features(RISCVCPU *cpu)
>  
>      cpu->cfg.ext_sha = riscv_has_ext(&cpu->env, RVH) &&
>                         cpu->cfg.ext_ssstateen;
> +
> +    cpu->cfg.ext_ziccrse = cpu->cfg.has_priv_1_11;
>  }
>  
>  static void riscv_cpu_validate_g(RISCVCPU *cpu)
> -- 
> 2.48.1
>

Other than my hangup on the commit message,

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
diff mbox series

Patch

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 522d6584e4..fc4632ce36 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -105,7 +105,7 @@  const RISCVIsaExtData isa_edata_arr[] = {
     ISA_EXT_DATA_ENTRY(ziccamoa, PRIV_VERSION_1_11_0, has_priv_1_11),
     ISA_EXT_DATA_ENTRY(ziccif, PRIV_VERSION_1_11_0, has_priv_1_11),
     ISA_EXT_DATA_ENTRY(zicclsm, PRIV_VERSION_1_11_0, has_priv_1_11),
-    ISA_EXT_DATA_ENTRY(ziccrse, PRIV_VERSION_1_11_0, has_priv_1_11),
+    ISA_EXT_DATA_ENTRY(ziccrse, PRIV_VERSION_1_11_0, ext_ziccrse),
     ISA_EXT_DATA_ENTRY(zicfilp, PRIV_VERSION_1_12_0, ext_zicfilp),
     ISA_EXT_DATA_ENTRY(zicfiss, PRIV_VERSION_1_13_0, ext_zicfiss),
     ISA_EXT_DATA_ENTRY(zicond, PRIV_VERSION_1_12_0, ext_zicond),
@@ -1749,6 +1749,7 @@  const RISCVCPUMultiExtConfig riscv_cpu_named_features[] = {
     MULTI_EXT_CFG_BOOL("zic64b", ext_zic64b, true),
     MULTI_EXT_CFG_BOOL("ssstateen", ext_ssstateen, true),
     MULTI_EXT_CFG_BOOL("sha", ext_sha, true),
+    MULTI_EXT_CFG_BOOL("ziccrse", ext_ziccrse, true),
 
     { },
 };
diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
index 3f3c1118c0..8a843482cc 100644
--- a/target/riscv/cpu_cfg.h
+++ b/target/riscv/cpu_cfg.h
@@ -166,6 +166,9 @@  struct RISCVCPUConfig {
     bool has_priv_1_12;
     bool has_priv_1_11;
 
+    /* Always enabled for TCG if has_priv_1_11 */
+    bool ext_ziccrse;
+
     /* 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 ea8d77d06a..c93612b1da 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -360,6 +360,8 @@  static void riscv_cpu_update_named_features(RISCVCPU *cpu)
 
     cpu->cfg.ext_sha = riscv_has_ext(&cpu->env, RVH) &&
                        cpu->cfg.ext_ssstateen;
+
+    cpu->cfg.ext_ziccrse = cpu->cfg.has_priv_1_11;
 }
 
 static void riscv_cpu_validate_g(RISCVCPU *cpu)