linux-kernel - [PATCH v3 0/2] riscv: hwprobe: Add Zicbop support

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Message-ID: <20251020152924.64551-1-zihong.plct@isrc.iscas.ac.cn>
Date: Mon, 20 Oct 2025 23:29:12 +0800
From: Yao Zihong <zihong.plct@...c.iscas.ac.cn>
To: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: ajones@...tanamicro.com,
	alexghiti@...osinc.com,
	shuah@...nel.org,
	samuel.holland@...ive.com,
	evan@...osinc.com,
	cleger@...osinc.com,
	zihong.plct@...c.iscas.ac.cn,
	zihongyao@...look.com,
	zhangyin2018@...as.ac.cn,
	Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>
Subject: [PATCH v3 0/2] riscv: hwprobe: Add Zicbop support

Changes since v2:
------------------
- Squash the previous UAPI/kernel/doc patches(originally 1/4, 2/4, 3/4)
  into a single hwprobe patch for simplicity.
- Selftests:
  * Drop the `memory` clobber from the prefetch inline asm since it is
    pure hint.
  * Fix style problems. (Andrew Jones)
  * Merge the standalone prefetch test into 
    `tools/testing/selftests/riscv/hwprobe/cbo.c` (Andrew Jones)
  * Switch to `getopt_long` for option parsing. (Andrew Jones)

Changes since v1:
------------------
- Bump RISCV_HWPROBE_MAX_KEY (modified 1/4).
- Add documentation for the Zicbop hwprobe bit/key (new 3/4).
- Add a selftest(prefetch.c) for Zicbop (new 4/4).

Add UAPI and kernel plumbing to expose the Zicbop extension presence
and its block size through hwprobe. The interface mirrors
Zicbom/Zicboz. This allows userspace to safely discover and optimize
for Zicbop when available.

Background: Zicbop is mandated by the RVA22U64 profile. Downstream may
combine the presence bit with ZICBOP_BLOCK_SIZE to make profile-level
policy decisions or enable Zicbop-specific optimizations.


Yao Zihong (2):
  riscv: hwprobe: Expose Zicbop extension and its block size
  selftests/riscv: Add Zicbop prefetch test

 Documentation/arch/riscv/hwprobe.rst        |   8 +-
 arch/riscv/include/asm/hwprobe.h            |   2 +-
 arch/riscv/include/uapi/asm/hwprobe.h       |   2 +
 arch/riscv/kernel/sys_hwprobe.c             |   6 +
 tools/testing/selftests/riscv/hwprobe/cbo.c | 188 +++++++++++++++++---
 5 files changed, 175 insertions(+), 31 deletions(-)

-- 
2.47.2