linux-kernel - Re: [PATCH] riscv: hwprobe: export Zicntr and Zihpm extensions

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Message-ID: <66c418c1.7b0a0220.6faf8.1929@mx.google.com>
Date: Tue, 20 Aug 2024 06:17:04 +0200
From: Miquel Sabaté Solà <mikisabate@...il.com>
To: Conor Dooley <conor@...nel.org>
Cc: Jesse Taube <jesse@...osinc.com>,  paul.walmsley@...ive.com,
  palmer@...belt.com,  aou@...s.berkeley.edu,
  linux-riscv@...ts.infradead.org,  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: hwprobe: export Zicntr and Zihpm extensions

> On Mon, Aug 19, 2024 at 01:29:16PM -0400, Jesse Taube wrote:
>> On Sat, Aug 17, 2024 at 3:58 AM Miquel Sabaté Solà <mikisabate@...il.com> wrote:
>> >
>> > Export Zicntr and Zihpm ISA extensions through the hwprobe syscall.
>> >
>> > Signed-off-by: Miquel Sabaté Solà <mikisabate@...il.com>
>> > ---
>> >  Documentation/arch/riscv/hwprobe.rst  | 6 ++++++
>> >  arch/riscv/include/uapi/asm/hwprobe.h | 2 ++
>> >  arch/riscv/kernel/sys_hwprobe.c       | 2 ++
>> >  3 files changed, 10 insertions(+)
>> >
>> > diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
>> > index 3db60a0911df..5bb69c985cce 100644
>> > --- a/Documentation/arch/riscv/hwprobe.rst
>> > +++ b/Documentation/arch/riscv/hwprobe.rst
>> > @@ -188,10 +188,16 @@ The following keys are defined:
>> >         manual starting from commit 95cf1f9 ("Add changes requested by Ved
>> >         during signoff")
>> >
>> > +  * :c:macro:`RISCV_HWPROBE_EXT_ZICNTR`: The Zicntr extension version 2.0
>> > +       is supported as defined in the RISC-V ISA manual.
>> > +
>> >    * :c:macro:`RISCV_HWPROBE_EXT_ZIHINTPAUSE`: The Zihintpause extension is
>> >         supported as defined in the RISC-V ISA manual starting from commit
>> >         d8ab5c78c207 ("Zihintpause is ratified").
>> >
>> > +  * :c:macro:`RISCV_HWPROBE_EXT_ZIHPM`: The Zihpm extension version 2.0
>> > +       is supported as defined in the RISC-V ISA manual.
>> > +
>> >    * :c:macro:`RISCV_HWPROBE_EXT_ZVE32X`: The Vector sub-extension Zve32x is
>> >      supported, as defined by version 1.0 of the RISC-V Vector extension manual.
>> >
>> > diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
>> > index b706c8e47b02..098a815b3fd4 100644
>> > --- a/arch/riscv/include/uapi/asm/hwprobe.h
>> > +++ b/arch/riscv/include/uapi/asm/hwprobe.h
>> > @@ -72,6 +72,8 @@ struct riscv_hwprobe {
>> >  #define                RISCV_HWPROBE_EXT_ZCF           (1ULL << 46)
>> >  #define                RISCV_HWPROBE_EXT_ZCMOP         (1ULL << 47)
>> >  #define                RISCV_HWPROBE_EXT_ZAWRS         (1ULL << 48)
>> > +#define                RISCV_HWPROBE_EXT_ZICNTR        (1ULL << 49)
>> > +#define                RISCV_HWPROBE_EXT_ZIHPM         (1ULL << 50)
>> >  #define RISCV_HWPROBE_KEY_CPUPERF_0    5
>> >  #define                RISCV_HWPROBE_MISALIGNED_UNKNOWN        (0 << 0)
>> >  #define                RISCV_HWPROBE_MISALIGNED_EMULATED       (1 << 0)
>
> The sort here, by number, is fine.
>
>> > diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
>> > index 8d1b5c35d2a7..30aede1c90ff 100644
>> > --- a/arch/riscv/kernel/sys_hwprobe.c
>> > +++ b/arch/riscv/kernel/sys_hwprobe.c
>> > @@ -118,6 +118,8 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
>> >                 EXT_KEY(ZKSH);
>> >                 EXT_KEY(ZKT);
>> >                 EXT_KEY(ZTSO);
>> > +               EXT_KEY(ZICNTR);
>> > +               EXT_KEY(ZIHPM);
>> 
>> Conor, do we care about ordering?
>
> I would rather that they were sorted alphabetically. Adding to the end
> is nothing but a conflict generator and makes it harder to see what is
> and what is not in the list. IIRC Palmer applied the patch I sent a few
> weeks ago that sorted the entries in all of these EXT_KEY() lists.

Makes a lot of sense. Let me send a new version of the patch with they
keys sorted.

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