Re: [PATCH RFC] target: riscv: Add Svvptc extension support

[Andrew Jones]

On Tue, Feb 13, 2024 at 03:53:08PM +0100, Alexandre Ghiti wrote:
> The Svvptc extension describes a uarch that does not cache invalid TLB
> entries: that's the case for qemu so there is nothing particular to
> implement other than the introduction of this extension, which is done
> here.
> 
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> ---
> 
> That's an RFC since the extension has not been ratified yet.

Hi Alex,

No need for the RFC tag. You can add not-yet-ratified extension support
to QEMU as long as the CPU property is off by default (as you've done)
and you add it to the riscv_cpu_experimental_exts[] array with an "x-"
prefix on its property name.

Thanks,
drew

> 
>  target/riscv/cpu.c     | 2 ++
>  target/riscv/cpu_cfg.h | 1 +
>  2 files changed, 3 insertions(+)
> 
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 1b8d001d23..4beb5d0350 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -178,6 +178,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(svinval, PRIV_VERSION_1_12_0, ext_svinval),
>      ISA_EXT_DATA_ENTRY(svnapot, PRIV_VERSION_1_12_0, ext_svnapot),
>      ISA_EXT_DATA_ENTRY(svpbmt, PRIV_VERSION_1_12_0, ext_svpbmt),
> +    ISA_EXT_DATA_ENTRY(svvptc, PRIV_VERSION_1_12_0, ext_svvptc),
>      ISA_EXT_DATA_ENTRY(xtheadba, PRIV_VERSION_1_11_0, ext_xtheadba),
>      ISA_EXT_DATA_ENTRY(xtheadbb, PRIV_VERSION_1_11_0, ext_xtheadbb),
>      ISA_EXT_DATA_ENTRY(xtheadbs, PRIV_VERSION_1_11_0, ext_xtheadbs),
> @@ -1467,6 +1468,7 @@ const RISCVCPUMultiExtConfig riscv_cpu_extensions[] = {
>      MULTI_EXT_CFG_BOOL("svinval", ext_svinval, false),
>      MULTI_EXT_CFG_BOOL("svnapot", ext_svnapot, false),
>      MULTI_EXT_CFG_BOOL("svpbmt", ext_svpbmt, false),
> +    MULTI_EXT_CFG_BOOL("svvptc", ext_svvptc, false),
>  
>      MULTI_EXT_CFG_BOOL("zicntr", ext_zicntr, true),
>      MULTI_EXT_CFG_BOOL("zihpm", ext_zihpm, true),
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index 833bf58217..c973693b6e 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -77,6 +77,7 @@ struct RISCVCPUConfig {
>      bool ext_svinval;
>      bool ext_svnapot;
>      bool ext_svpbmt;
> +    bool ext_svvptc;
>      bool ext_zdinx;
>      bool ext_zaamo;
>      bool ext_zacas;
> -- 
> 2.39.2
> 
>