linux-kernel - [PATCH v7 2/3] RISC-V: hwprobe: Expose Zicbom extension and its block size

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Message-Id: <20250226063206.71216-3-cuiyunhui@bytedance.com>
Date: Wed, 26 Feb 2025 14:32:05 +0800
From: Yunhui Cui <cuiyunhui@...edance.com>
To: ajones@...tanamicro.com,
	alexghiti@...osinc.com,
	andybnac@...il.com,
	aou@...s.berkeley.edu,
	charlie@...osinc.com,
	cleger@...osinc.com,
	conor.dooley@...rochip.com,
	conor@...nel.org,
	corbet@....net,
	cuiyunhui@...edance.com,
	evan@...osinc.com,
	jesse@...osinc.com,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	palmer@...belt.com,
	paul.walmsley@...ive.com,
	samuel.holland@...ive.com,
	shuah@...nel.org
Subject: [PATCH v7 2/3] RISC-V: hwprobe: Expose Zicbom extension and its block size

Expose Zicbom through hwprobe and also provide a key to extract its
respective block size.

Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
Reviewed-by: Samuel Holland <samuel.holland@...ive.com>
Signed-off-by: Yunhui Cui <cuiyunhui@...edance.com>
---
 Documentation/arch/riscv/hwprobe.rst  | 6 ++++++
 arch/riscv/include/asm/hwprobe.h      | 2 +-
 arch/riscv/include/uapi/asm/hwprobe.h | 2 ++
 arch/riscv/kernel/sys_hwprobe.c       | 8 +++++++-
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
index f273ea15a8e8..d91e39e19ea0 100644
--- a/Documentation/arch/riscv/hwprobe.rst
+++ b/Documentation/arch/riscv/hwprobe.rst
@@ -242,6 +242,9 @@ The following keys are defined:
   * :c:macro:`RISCV_HWPROBE_EXT_SUPM`: The Supm extension is supported as
        defined in version 1.0 of the RISC-V Pointer Masking extensions.
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZICBOM`: The Zicbom 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.
@@ -303,3 +306,6 @@ The following keys are defined:
     * :c:macro:`RISCV_HWPROBE_VENDOR_EXT_XTHEADVECTOR`: The xtheadvector vendor
         extension is supported in the T-Head ISA extensions spec starting from
 	commit a18c801634 ("Add T-Head VECTOR vendor extension. ").
+
+* :c:macro:`RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE`: An unsigned int which
+  represents the size of the Zicbom block in bytes.
diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
index dd624523981c..1f690fea0e03 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 11
+#define RISCV_HWPROBE_MAX_KEY 12
 
 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 c3c1cc951cb9..8c706cde3777 100644
--- a/arch/riscv/include/uapi/asm/hwprobe.h
+++ b/arch/riscv/include/uapi/asm/hwprobe.h
@@ -73,6 +73,7 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_ZCMOP		(1ULL << 47)
 #define		RISCV_HWPROBE_EXT_ZAWRS		(1ULL << 48)
 #define		RISCV_HWPROBE_EXT_SUPM		(1ULL << 49)
+#define		RISCV_HWPROBE_EXT_ZICBOM	(1ULL << 50)
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)
@@ -95,6 +96,7 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_MISALIGNED_VECTOR_FAST		3
 #define		RISCV_HWPROBE_MISALIGNED_VECTOR_UNSUPPORTED	4
 #define RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0	11
+#define RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE	12
 /* 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 04a4e5495512..69fe9da320dc 100644
--- a/arch/riscv/kernel/sys_hwprobe.c
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -107,6 +107,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 		EXT_KEY(ZCA);
 		EXT_KEY(ZCB);
 		EXT_KEY(ZCMOP);
+		EXT_KEY(ZICBOM);
 		EXT_KEY(ZICBOZ);
 		EXT_KEY(ZICOND);
 		EXT_KEY(ZIHINTNTL);
@@ -161,7 +162,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 	pair->value &= ~missing;
 }
 
-static bool hwprobe_ext0_has(const struct cpumask *cpus, unsigned long ext)
+static bool hwprobe_ext0_has(const struct cpumask *cpus, u64 ext)
 {
 	struct riscv_hwprobe pair;
 
@@ -279,6 +280,11 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
 		if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOZ))
 			pair->value = riscv_cboz_block_size;
 		break;
+	case RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE:
+		pair->value = 0;
+		if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOM))
+			pair->value = riscv_cbom_block_size;
+		break;
 	case RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS:
 		pair->value = user_max_virt_addr();
 		break;
-- 
2.39.2