Re: [PATCH v10 10/14] riscv: hwprobe: Add thead vendor extension probing

From: Emil Renner Berthing
Date: Wed Oct 02 2024 - 12:59:52 EST

Charlie Jenkins wrote:
> Add a new hwprobe key "RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0" which
> allows userspace to probe for the new RISCV_ISA_VENDOR_EXT_XTHEADVECTOR
> vendor extension.
>
> This new key will allow userspace code to probe for which thead vendor
> extensions are supported. This API is modeled to be consistent with
> RISCV_HWPROBE_KEY_IMA_EXT_0. The bitmask returned will have each bit
> corresponding to a supported thead vendor extension of the cpumask set.
> Just like RISCV_HWPROBE_KEY_IMA_EXT_0, this allows a userspace program
> to determine all of the supported thead vendor extensions in one call.
>
> Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
> Reviewed-by: Evan Green <evan@xxxxxxxxxxxx>
> ---
> arch/riscv/include/asm/hwprobe.h | 3 +-
> .../include/asm/vendor_extensions/thead_hwprobe.h | 19 +++++++++++
> .../include/asm/vendor_extensions/vendor_hwprobe.h | 37 ++++++++++++++++++++++
> arch/riscv/include/uapi/asm/hwprobe.h | 3 +-
> arch/riscv/include/uapi/asm/vendor/thead.h | 3 ++
> arch/riscv/kernel/sys_hwprobe.c | 5 +++
> arch/riscv/kernel/vendor_extensions/Makefile | 1 +
> .../riscv/kernel/vendor_extensions/thead_hwprobe.c | 19 +++++++++++
> 8 files changed, 88 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
> index ef01c182af2b..6148e1eab64c 100644
> --- a/arch/riscv/include/asm/hwprobe.h
> +++ b/arch/riscv/include/asm/hwprobe.h
> @@ -1,6 +1,6 @@
> /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> /*
> - * Copyright 2023 Rivos, Inc
> + * Copyright 2023-2024 Rivos, Inc
> */
>
> #ifndef _ASM_HWPROBE_H
> @@ -21,6 +21,7 @@ static inline bool hwprobe_key_is_bitmask(__s64 key)
> case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
> case RISCV_HWPROBE_KEY_IMA_EXT_0:
> case RISCV_HWPROBE_KEY_CPUPERF_0:
> + case RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0:
> return true;
> }
>
> diff --git a/arch/riscv/include/asm/vendor_extensions/thead_hwprobe.h b/arch/riscv/include/asm/vendor_extensions/thead_hwprobe.h
> new file mode 100644
> index 000000000000..65a9c5612466
> --- /dev/null
> +++ b/arch/riscv/include/asm/vendor_extensions/thead_hwprobe.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_VENDOR_EXTENSIONS_THEAD_HWPROBE_H
> +#define _ASM_RISCV_VENDOR_EXTENSIONS_THEAD_HWPROBE_H
> +
> +#include <linux/cpumask.h>
> +
> +#include <uapi/asm/hwprobe.h>
> +
> +#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_THEAD
> +void hwprobe_isa_vendor_ext_thead_0(struct riscv_hwprobe *pair, const struct cpumask *cpus);
> +#else
> +static inline void hwprobe_isa_vendor_ext_thead_0(struct riscv_hwprobe *pair,
> + const struct cpumask *cpus)
> +{
> + pair->value = 0;
> +}
> +#endif
> +
> +#endif
> diff --git a/arch/riscv/include/asm/vendor_extensions/vendor_hwprobe.h b/arch/riscv/include/asm/vendor_extensions/vendor_hwprobe.h
> new file mode 100644
> index 000000000000..6b9293e984a9
> --- /dev/null
> +++ b/arch/riscv/include/asm/vendor_extensions/vendor_hwprobe.h
> @@ -0,0 +1,37 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright 2024 Rivos, Inc
> + */
> +
> +#ifndef _ASM_RISCV_SYS_HWPROBE_H
> +#define _ASM_RISCV_SYS_HWPROBE_H
> +
> +#include <asm/cpufeature.h>
> +
> +#define VENDOR_EXT_KEY(ext) \
> + do { \
> + if (__riscv_isa_extension_available(isainfo->isa, RISCV_ISA_VENDOR_EXT_##ext)) \
> + pair->value |= RISCV_HWPROBE_VENDOR_EXT_##ext; \
> + else \
> + missing |= RISCV_HWPROBE_VENDOR_EXT_##ext; \
> + } while (false)
> +
> +/*
> + * Loop through and record extensions that 1) anyone has, and 2) anyone
> + * doesn't have.
> + *
> + * _extension_checks is an arbitrary C block to set the values of pair->value
> + * and missing. It should be filled with VENDOR_EXT_KEY expressions.
> + */
> +#define VENDOR_EXTENSION_SUPPORTED(pair, cpus, per_hart_vendor_bitmap, _extension_checks) \
> + do { \
> + int cpu; \
> + u64 missing = 0; \
> + for_each_cpu(cpu, (cpus)) { \
> + struct riscv_isavendorinfo *isainfo = &(per_hart_vendor_bitmap)[cpu]; \
> + _extension_checks \
> + } \
> + (pair)->value &= ~missing; \
> + } while (false) \
> +
> +#endif /* _ASM_RISCV_SYS_HWPROBE_H */
> diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
> index b706c8e47b02..452d0b84f17f 100644
> --- a/arch/riscv/include/uapi/asm/hwprobe.h
> +++ b/arch/riscv/include/uapi/asm/hwprobe.h
> @@ -1,6 +1,6 @@
> /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> /*
> - * Copyright 2023 Rivos, Inc
> + * Copyright 2023-2024 Rivos, Inc
> */
>
> #ifndef _UAPI_ASM_HWPROBE_H
> @@ -82,6 +82,7 @@ struct riscv_hwprobe {
> #define RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE 6
> #define RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS 7
> #define RISCV_HWPROBE_KEY_TIME_CSR_FREQ 8
> +#define RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 9
> /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */

I wanted to try this patchset on my Nezha board, but rebasing on v6.11
this conflicts with

c42e2f076769 ("RISC-V: hwprobe: Add MISALIGNED_PERF key")

While fixing it up I bumped the RISCV_HWPROBE_MAX_KEY as the comment above told
me to do, but now I notice you don't do that in this patch. Is that a bug or am
I misunderstanding something?

/Emil

>
> /* Flags */
> diff --git a/arch/riscv/include/uapi/asm/vendor/thead.h b/arch/riscv/include/uapi/asm/vendor/thead.h
> new file mode 100644
> index 000000000000..43790ebe5faf
> --- /dev/null
> +++ b/arch/riscv/include/uapi/asm/vendor/thead.h
> @@ -0,0 +1,3 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +
> +#define RISCV_HWPROBE_VENDOR_EXT_XTHEADVECTOR (1 << 0)
> diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
> index 8d1b5c35d2a7..5a3dc8e66c85 100644
> --- a/arch/riscv/kernel/sys_hwprobe.c
> +++ b/arch/riscv/kernel/sys_hwprobe.c
> @@ -15,6 +15,7 @@
> #include <asm/uaccess.h>
> #include <asm/unistd.h>
> #include <asm/vector.h>
> +#include <asm/vendor_extensions/thead_hwprobe.h>
> #include <vdso/vsyscall.h>
>
>
> @@ -241,6 +242,10 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
> pair->value = riscv_timebase;
> break;
>
> + case RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0:
> + hwprobe_isa_vendor_ext_thead_0(pair, cpus);
> + break;
> +
> /*
> * For forward compatibility, unknown keys don't fail the whole
> * call, but get their element key set to -1 and value set to 0
> diff --git a/arch/riscv/kernel/vendor_extensions/Makefile b/arch/riscv/kernel/vendor_extensions/Makefile
> index 353522cb3bf0..866414c81a9f 100644
> --- a/arch/riscv/kernel/vendor_extensions/Makefile
> +++ b/arch/riscv/kernel/vendor_extensions/Makefile
> @@ -2,3 +2,4 @@
>
> obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_ANDES) += andes.o
> obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_THEAD) += thead.o
> +obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_THEAD) += thead_hwprobe.o
> diff --git a/arch/riscv/kernel/vendor_extensions/thead_hwprobe.c b/arch/riscv/kernel/vendor_extensions/thead_hwprobe.c
> new file mode 100644
> index 000000000000..2eba34011786
> --- /dev/null
> +++ b/arch/riscv/kernel/vendor_extensions/thead_hwprobe.c
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <asm/vendor_extensions/thead.h>
> +#include <asm/vendor_extensions/thead_hwprobe.h>
> +#include <asm/vendor_extensions/vendor_hwprobe.h>
> +
> +#include <linux/cpumask.h>
> +#include <linux/types.h>
> +
> +#include <uapi/asm/hwprobe.h>
> +#include <uapi/asm/vendor/thead.h>
> +
> +void hwprobe_isa_vendor_ext_thead_0(struct riscv_hwprobe *pair, const struct cpumask *cpus)
> +{
> + VENDOR_EXTENSION_SUPPORTED(pair, cpus,
> + riscv_isa_vendor_ext_list_thead.per_hart_isa_bitmap, {
> + VENDOR_EXT_KEY(XTHEADVECTOR);
> + });
> +}
>
> --
> 2.45.0
>
>
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