[PATCH v7 10/13] riscv: hwprobe: Add thead vendor extension probing

[Charlie Jenkins <charlie@rivosinc.com>]

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@rivosinc.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
---
 arch/riscv/include/asm/hwprobe.h                   |  5 +--
 .../include/asm/vendor_extensions/thead_hwprobe.h  | 18 +++++++++++
 .../include/asm/vendor_extensions/vendor_hwprobe.h | 37 ++++++++++++++++++++++
 arch/riscv/include/uapi/asm/hwprobe.h              |  3 +-
 arch/riscv/include/uapi/asm/vendor/thead.h         |  3 ++
 arch/riscv/kernel/sys_hwprobe.c                    |  5 +++
 arch/riscv/kernel/vendor_extensions/Makefile       |  1 +
 .../riscv/kernel/vendor_extensions/thead_hwprobe.c | 19 +++++++++++
 8 files changed, 88 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h
index 150a9877b0af..6148e1eab64c 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 7
+#define RISCV_HWPROBE_MAX_KEY 8
 
 static inline bool riscv_hwprobe_key_is_valid(__s64 key)
 {
@@ -21,6 +21,7 @@ static inline bool hwprobe_key_is_bitmask(__s64 key)
 	case RISCV_HWPROBE_KEY_BASE_BEHAVIOR:
 	case RISCV_HWPROBE_KEY_IMA_EXT_0:
 	case RISCV_HWPROBE_KEY_CPUPERF_0:
+	case RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0:
 		return true;
 	}
 
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..925fef39a2c0
--- /dev/null
+++ b/arch/riscv/include/asm/vendor_extensions/thead_hwprobe.h
@@ -0,0 +1,18 @@
+/* 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>
+
+#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_THEAD
+void hwprobe_isa_vendor_ext_thead_0(struct riscv_hwprobe *pair, const struct cpumask *cpus);
+#else
+static inline void hwprobe_isa_vendor_ext_thead_0(struct riscv_hwprobe *pair, const struct cpumask *cpus)
+{
+	pair->value = 0;
+}
+#endif
+
+#endif
diff --git a/arch/riscv/include/asm/vendor_extensions/vendor_hwprobe.h b/arch/riscv/include/asm/vendor_extensions/vendor_hwprobe.h
new file mode 100644
index 000000000000..f28f31e19cda
--- /dev/null
+++ b/arch/riscv/include/asm/vendor_extensions/vendor_hwprobe.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2024 Rivos, Inc
+ */
+
+#ifndef _ASM_RISCV_SYS_HWPROBE_H
+#define _ASM_RISCV_SYS_HWPROBE_H
+
+#include <asm/cpufeature.h>
+
+#define VENDOR_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)
+
+/*
+ * Loop through and record extensions that 1) anyone has, and 2) anyone
+ * doesn't have.
+ *
+ * _extension_checks is an arbitrary C block to set the values of pair->value
+ * and missing. It should be filled with VENDOR_EXT_KEY expressions.
+ */
+#define VENDOR_EXTENSION_SUPPORTED(pair, cpus, per_hart_vendor_bitmap, _extension_checks)	\
+	do {											\
+		int cpu;									\
+		u64 missing;									\
+		for_each_cpu(cpu, (cpus)) {							\
+			struct riscv_isavendorinfo *isainfo = &(per_hart_vendor_bitmap)[cpu];	\
+			_extension_checks							\
+		}										\
+		(pair)->value &= ~missing;							\
+	} while (false)										\
+
+#endif /* _ASM_RISCV_SYS_HWPROBE_H */
diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h
index 8b8f6ac0eae2..73ab65ac8c55 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
@@ -81,6 +81,7 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_MISALIGNED_MASK		(7 << 0)
 #define RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE	6
 #define RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS	7
+#define RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0	8
 /* 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 685594769535..4cecdb0249a2 100644
--- a/arch/riscv/kernel/sys_hwprobe.c
+++ b/arch/riscv/kernel/sys_hwprobe.c
@@ -14,6 +14,7 @@
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/vector.h>
+#include <asm/vendor_extensions/thead_hwprobe.h>
 #include <vdso/vsyscall.h>
 
 
@@ -237,6 +238,10 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
 		pair->value = user_max_virt_addr();
 		break;
 
+	case RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0:
+		hwprobe_isa_vendor_ext_thead_0(pair, cpus);
+		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 353522cb3bf0..866414c81a9f 100644
--- a/arch/riscv/kernel/vendor_extensions/Makefile
+++ b/arch/riscv/kernel/vendor_extensions/Makefile
@@ -2,3 +2,4 @@
 
 obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_ANDES)	+= andes.o
 obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_THEAD)	+= thead.o
+obj-$(CONFIG_RISCV_ISA_VENDOR_EXT_THEAD)	+= thead_hwprobe.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..2eba34011786
--- /dev/null
+++ b/arch/riscv/kernel/vendor_extensions/thead_hwprobe.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <asm/vendor_extensions/thead.h>
+#include <asm/vendor_extensions/thead_hwprobe.h>
+#include <asm/vendor_extensions/vendor_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)
+{
+	VENDOR_EXTENSION_SUPPORTED(pair, cpus,
+				   riscv_isa_vendor_ext_list_thead.per_hart_isa_bitmap, {
+		VENDOR_EXT_KEY(XTHEADVECTOR);
+	});
+}

-- 
2.44.0