[PATCH 3/6] RISC-V: hwprobe: Expose Zicboz extension and its block size

[Conor Dooley]

On Wed, Aug 09, 2023 at 01:55:20PM +0200, Andrew Jones wrote:
> Expose Zicboz through hwprobe and also provide a key to extract its
> respective block size. Opportunistically add a macro and apply it to
> current extensions in order to avoid duplicating code.
> 
> Signed-off-by: Andrew Jones <ajones at ventanamicro.com>
> ---
>  Documentation/riscv/hwprobe.rst       |  6 ++++
>  arch/riscv/include/asm/hwprobe.h      |  2 +-
>  arch/riscv/include/uapi/asm/hwprobe.h |  2 ++
>  arch/riscv/kernel/sys_riscv.c         | 41 ++++++++++++++++++---------
>  4 files changed, 36 insertions(+), 15 deletions(-)
> 
> diff --git a/Documentation/riscv/hwprobe.rst b/Documentation/riscv/hwprobe.rst
> index 933c715065d6..6a17c2872660 100644
> --- a/Documentation/riscv/hwprobe.rst
> +++ b/Documentation/riscv/hwprobe.rst
> @@ -77,6 +77,9 @@ The following keys are defined:
>    * :c:macro:`RISCV_HWPROBE_EXT_ZBS`: The Zbs extension is supported, as defined
>         in version 1.0 of the Bit-Manipulation ISA extensions.
>  
> +  * :c:macro:`RISCV_HWPROBE_EXT_ZICBOZ`: The Zicboz extension is supported, as
> +       ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs.
> +
>  * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
>    information about the selected set of processors.
>  
> @@ -97,3 +100,6 @@ The following keys are defined:
>  
>    * :c:macro:`RISCV_HWPROBE_MISALIGNED_UNSUPPORTED`: Misaligned accesses are
>      not supported at all and will generate a misaligned address fault.
> +
> +* :c:macro:`RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE`: An unsigned int which
> +  represents the size of the Zicboz block in bytes.
> diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
> index 78936f4ff513..39df8604fea1 100644
> --- a/arch/riscv/include/asm/hwprobe.h
> +++ b/arch/riscv/include/asm/hwprobe.h
> @@ -8,6 +8,6 @@
>  
>  #include <uapi/asm/hwprobe.h>
>  
> -#define RISCV_HWPROBE_MAX_KEY 5
> +#define RISCV_HWPROBE_MAX_KEY 6
>  
>  #endif
> diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
> index 006bfb48343d..86d08a0e617b 100644
> --- a/arch/riscv/include/uapi/asm/hwprobe.h
> +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> @@ -29,6 +29,7 @@ struct riscv_hwprobe {
>  #define		RISCV_HWPROBE_EXT_ZBA		(1 << 3)
>  #define		RISCV_HWPROBE_EXT_ZBB		(1 << 4)
>  #define		RISCV_HWPROBE_EXT_ZBS		(1 << 5)
> +#define		RISCV_HWPROBE_EXT_ZICBOZ	(1 << 6)
>  #define RISCV_HWPROBE_KEY_CPUPERF_0	5
>  #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
>  #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)
> @@ -36,6 +37,7 @@ struct riscv_hwprobe {
>  #define		RISCV_HWPROBE_MISALIGNED_FAST		(3 << 0)
>  #define		RISCV_HWPROBE_MISALIGNED_UNSUPPORTED	(4 << 0)
>  #define		RISCV_HWPROBE_MISALIGNED_MASK		(7 << 0)
> +#define RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE	6
>  /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */
>  
>  #endif
> diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
> index 26ef5526bfb4..7d970358597b 100644
> --- a/arch/riscv/kernel/sys_riscv.c
> +++ b/arch/riscv/kernel/sys_riscv.c
> @@ -145,26 +145,33 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
>  	for_each_cpu(cpu, cpus) {
>  		struct riscv_isainfo *isainfo = &hart_isa[cpu];
>  
> -		if (riscv_isa_extension_available(isainfo->isa, ZBA))
> -			pair->value |= RISCV_HWPROBE_EXT_ZBA;
> -		else
> -			missing |= RISCV_HWPROBE_EXT_ZBA;
> -
> -		if (riscv_isa_extension_available(isainfo->isa, ZBB))
> -			pair->value |= RISCV_HWPROBE_EXT_ZBB;
> -		else
> -			missing |= RISCV_HWPROBE_EXT_ZBB;
> -
> -		if (riscv_isa_extension_available(isainfo->isa, ZBS))
> -			pair->value |= RISCV_HWPROBE_EXT_ZBS;
> -		else
> -			missing |= RISCV_HWPROBE_EXT_ZBS;
> +#define EXT_KEY(ext)									\
> +	do {										\
> +		if (__riscv_isa_extension_available(isainfo->isa, RISCV_ISA_EXT_##ext))	\
> +			pair->value |= RISCV_HWPROBE_EXT_##ext;				\
> +		else									\
> +			missing |= RISCV_HWPROBE_EXT_##ext;				\
> +	} while (false)

Would you mind adding a comment here that using this macro is only
permitted for extensions that can be used by userspace regardless of kernel
config options?

> +		EXT_KEY(ZBA);
> +		EXT_KEY(ZBB);
> +		EXT_KEY(ZBS);
> +		EXT_KEY(ZICBOZ);
> +#undef EXT_KEY
>  	}
>  
>  	/* Now turn off reporting features if any CPU is missing it. */
>  	pair->value &= ~missing;
>  }
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 228 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-riscv/attachments/20230810/e059c68a/attachment.sig>