linux-kernel - [PATCH v4 1/2] riscv: hwprobe: Expose Zicbop extension and its block size

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Message-ID: <20251117163333.31182-2-zihong.plct@isrc.iscas.ac.cn>
Date: Tue, 18 Nov 2025 00:32:39 +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,
	zihong.plct@...c.iscas.ac.cn,
	zihongyao@...look.com,
	zhangyin2018@...as.ac.cn,
	Jonathan Corbet <corbet@....net>,
	Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Clément Léger <cleger@...osinc.com>,
	Cyan Yang <cyan.yang@...ive.com>,
	Yunhui Cui <cuiyunhui@...edance.com>,
	Charlie Jenkins <charlie@...osinc.com>,
	Miquel Sabaté Solà <mikisabate@...il.com>,
	Nam Cao <namcao@...utronix.de>,
	Jingwei Wang <wangjingwei@...as.ac.cn>,
	Aleksa Paunovic <aleksa.paunovic@...cgroup.com>,
	Inochi Amaoto <inochiama@...il.com>,
	Thomas Weißschuh <thomas.weissschuh@...utronix.de>,
	linux-doc@...r.kernel.org (open list:DOCUMENTATION)
Subject: [PATCH v4 1/2] riscv: hwprobe: Expose Zicbop extension and its block size

- Add `RISCV_HWPROBE_EXT_ZICBOP` to report the presence of the
  Zicbop extension.
- Add `RISCV_HWPROBE_KEY_ZICBOP_BLOCK_SIZE` to expose the block
  size (in bytes) when Zicbop is supported.
- Update hwprobe.rst to document the new extension bit and block
  size key, following the existing Zicbom/Zicboz style.

Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
Signed-off-by: Yao Zihong <zihong.plct@...c.iscas.ac.cn>
---
 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 ++++++
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
index 2f449c9b15bd..52f12af43b9d 100644
--- a/Documentation/arch/riscv/hwprobe.rst
+++ b/Documentation/arch/riscv/hwprobe.rst
@@ -275,6 +275,9 @@ The following keys are defined:
        ratified in commit 49f49c842ff9 ("Update to Rafified state") of
        riscv-zabha.
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZICBOP`: The Zicbop extension is supported, as
+       ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs.
+
 * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: Deprecated.  Returns similar values to
      :c:macro:`RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF`, but the key was
      mistakenly classified as a bitmask rather than a value.
@@ -369,4 +372,7 @@ The following keys are defined:
 
     * :c:macro:`RISCV_HWPROBE_VENDOR_EXT_XSFVFWMACCQQQ`: The Xsfvfwmaccqqq
         vendor extension is supported in version 1.0 of Matrix Multiply Accumulate
-	Instruction Extensions Specification.
\ No newline at end of file
+	Instruction Extensions Specification.
+
+* :c:macro:`RISCV_HWPROBE_KEY_ZICBOP_BLOCK_SIZE`: An unsigned int which
+  represents the size of the Zicbop block in bytes.
diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
index 58f8dda73259..8c572a464719 100644
--- a/arch/riscv/include/asm/hwprobe.h
+++ b/arch/riscv/include/asm/hwprobe.h
@@ -8,7 +8,7 @@
 
 #include <uapi/asm/hwprobe.h>
 
-#define RISCV_HWPROBE_MAX_KEY 14
+#define RISCV_HWPROBE_MAX_KEY 15
 
 static inline bool riscv_hwprobe_key_is_valid(__s64 key)
 {
diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
index 5d30a4fae37a..9cc508be54c5 100644
--- a/arch/riscv/include/uapi/asm/hwprobe.h
+++ b/arch/riscv/include/uapi/asm/hwprobe.h
@@ -82,6 +82,7 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_ZAAMO		(1ULL << 56)
 #define		RISCV_HWPROBE_EXT_ZALRSC	(1ULL << 57)
 #define		RISCV_HWPROBE_EXT_ZABHA		(1ULL << 58)
+#define		RISCV_HWPROBE_EXT_ZICBOP	(1ULL << 59)
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)
@@ -107,6 +108,7 @@ struct riscv_hwprobe {
 #define RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE	12
 #define RISCV_HWPROBE_KEY_VENDOR_EXT_SIFIVE_0	13
 #define RISCV_HWPROBE_KEY_VENDOR_EXT_MIPS_0	14
+#define RISCV_HWPROBE_KEY_ZICBOP_BLOCK_SIZE	15
 /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */
 
 /* Flags */
diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c
index 199d13f86f31..6b33fd88bf3e 100644
--- a/arch/riscv/kernel/sys_hwprobe.c
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -122,6 +122,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 		EXT_KEY(ZCB);
 		EXT_KEY(ZCMOP);
 		EXT_KEY(ZICBOM);
+		EXT_KEY(ZICBOP);
 		EXT_KEY(ZICBOZ);
 		EXT_KEY(ZICNTR);
 		EXT_KEY(ZICOND);
@@ -302,6 +303,11 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
 		if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOM))
 			pair->value = riscv_cbom_block_size;
 		break;
+	case RISCV_HWPROBE_KEY_ZICBOP_BLOCK_SIZE:
+		pair->value = 0;
+		if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOP))
+			pair->value = riscv_cbop_block_size;
+		break;
 	case RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS:
 		pair->value = user_max_virt_addr();
 		break;
-- 
2.47.2