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Message-ID: <ZjKc6I9vf5fYcQZe@ghost>
Date: Wed, 1 May 2024 12:50:00 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Evan Green <evan@...osinc.com>
Cc: Conor Dooley <conor@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>, Guo Ren <guoren@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Samuel Holland <samuel@...lland.org>,
Conor Dooley <conor.dooley@...rochip.com>,
Clément Léger <cleger@...osinc.com>,
Jonathan Corbet <corbet@....net>, Shuah Khan <shuah@...nel.org>,
linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, Palmer Dabbelt <palmer@...osinc.com>,
linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v4 13/16] riscv: hwprobe: Add thead vendor extension
probing
On Wed, May 01, 2024 at 09:46:00AM -0700, Evan Green wrote:
> On Fri, Apr 26, 2024 at 2:37 PM Charlie Jenkins <charlie@...osinc.com> 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@...osinc.com>
> > ---
> > arch/riscv/include/asm/hwprobe.h | 4 +--
> > .../include/asm/vendor_extensions/thead_hwprobe.h | 11 ++++++
> > arch/riscv/include/uapi/asm/hwprobe.h | 3 +-
> > arch/riscv/include/uapi/asm/vendor/thead.h | 3 ++
> > arch/riscv/kernel/sys_hwprobe.c | 9 +++++
> > arch/riscv/kernel/vendor_extensions/Makefile | 1 +
> > .../riscv/kernel/vendor_extensions/thead_hwprobe.c | 42 ++++++++++++++++++++++
> > 7 files changed, 70 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
> > index 630507dff5ea..e68496b4f8de 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
> > @@ -8,7 +8,7 @@
> >
> > #include <uapi/asm/hwprobe.h>
> >
> > -#define RISCV_HWPROBE_MAX_KEY 6
> > +#define RISCV_HWPROBE_MAX_KEY 7
> >
> > static inline bool riscv_hwprobe_key_is_valid(__s64 key)
> > {
> > 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..907cfc4eb4dc
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/vendor_extensions/thead_hwprobe.h
> > @@ -0,0 +1,11 @@
> > +/* 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>
> > +
> > +void hwprobe_isa_vendor_ext_thead_0(struct riscv_hwprobe *pair, const struct cpumask *cpus);
> > +
> > +#endif
> > diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
> > index 9f2a8e3ff204..21e96a63f9ea 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
> > @@ -67,6 +67,7 @@ struct riscv_hwprobe {
> > #define RISCV_HWPROBE_MISALIGNED_UNSUPPORTED (4 << 0)
> > #define RISCV_HWPROBE_MISALIGNED_MASK (7 << 0)
> > #define RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE 6
> > +#define RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 7
> > /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */
> >
> > /* 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 8cae41a502dd..e59cac545df5 100644
> > --- a/arch/riscv/kernel/sys_hwprobe.c
> > +++ b/arch/riscv/kernel/sys_hwprobe.c
> > @@ -13,6 +13,7 @@
> > #include <asm/uaccess.h>
> > #include <asm/unistd.h>
> > #include <asm/vector.h>
> > +#include <asm/vendor_extensions/thead_hwprobe.h>
> > #include <vdso/vsyscall.h>
> >
> >
> > @@ -216,6 +217,14 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
> > pair->value = riscv_cboz_block_size;
> > break;
> >
> > + case RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0:
> > +#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_THEAD
> > + hwprobe_isa_vendor_ext_thead_0(pair, cpus);
> > +#else
> > + pair->value = 0;
> > +#endif
>
> Could we move this ifdef into the header by declaring a dummy
> hwprobe_isa_vendor_ext_thead_0() in the header for the !ENABLED case?
Whoops I didn't respond to this in my last message, this is a good idea,
thanks!
- Charlie
>
> > + 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 8f1c5a4dc38f..f511fd269e8a 100644
> > --- a/arch/riscv/kernel/vendor_extensions/Makefile
> > +++ b/arch/riscv/kernel/vendor_extensions/Makefile
> > @@ -1,4 +1,5 @@
> > # SPDX-License-Identifier: GPL-2.0-only
> >
> > obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_THEAD) += thead.o
> > +obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_THEAD) += thead_hwprobe.o
> > obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_ANDES) += andes.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..e8e2de292032
> > --- /dev/null
> > +++ b/arch/riscv/kernel/vendor_extensions/thead_hwprobe.c
> > @@ -0,0 +1,42 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +
> > +#include <asm/vector.h>
> > +#include <asm/vendor_extensions/thead.h>
> > +#include <asm/vendor_extensions/thead_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)
> > +{
> > + /*
> > + * Loop through and record extensions that 1) anyone has, and 2) anyone
> > + * doesn't have.
> > + */
> > +
> > + struct riscv_isainfo *per_hart_thead_bitmap = riscv_isa_vendor_ext_list_thead.per_hart_vendor_bitmap;
> > + int cpu;
> > + u64 missing;
> > +
> > + for_each_cpu(cpu, cpus) {
> > + struct riscv_isainfo *isainfo = &per_hart_thead_bitmap[cpu];
> > +
> > +#define 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)
> > +
> > + EXT_KEY(XTHEADVECTOR);
> > +
> > +#undef EXT_KEY
> > + }
> > +
> > + /* Now turn off reporting features if any CPU is missing it. */> + pair->value &= ~missing;
> > +}
>
> Something to consider, perhaps when there's a second vendor, is how we
> might reduce this boilerplate on the second vendor. Probably best to
> wait though until we know exactly what the commonalities are. This
> looks good for now.
>
>
> >
> > --
> > 2.44.0
> >
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