riscv: hwprobe: export Zfa ISA extension

Export Zfa ISA extension[1] through hwprobe.

Link: https://drive.google.com/file/d/1VT6QIggpb59-8QRV266dEE4T8FZTxGq4/view [1]
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Link: https://lore.kernel.org/r/20231114141256.126749-20-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: clementleger

Documentation/arch/riscv/hwprobe.rst

@@ -157,6 +157,10 @@ The following keys are defined:
        defined in the RISC-V Vector manual starting from commit e2ccd0548d6c
        ("Remove draft warnings from Zvfh[min]").
 
+  * :c:macro:`RISCV_HWPROBE_EXT_ZFA`: The Zfa extension is supported as
+       defined in the RISC-V ISA manual starting from commit 056b6ff467c7
+       ("Zfa is ratified").
+
 * :c:macro:`RISCV_HWPROBE_KEY_CPUPERF_0`: A bitmask that contains performance
   information about the selected set of processors.
 

arch/riscv/include/uapi/asm/hwprobe.h

@@ -55,6 +55,7 @@ struct riscv_hwprobe {
 #define		RISCV_HWPROBE_EXT_ZIHINTNTL	(1 << 29)
 #define		RISCV_HWPROBE_EXT_ZVFH		(1 << 30)
 #define		RISCV_HWPROBE_EXT_ZVFHMIN	(1 << 31)
+#define		RISCV_HWPROBE_EXT_ZFA		(1ULL << 32)
 #define RISCV_HWPROBE_KEY_CPUPERF_0	5
 #define		RISCV_HWPROBE_MISALIGNED_UNKNOWN	(0 << 0)
 #define		RISCV_HWPROBE_MISALIGNED_EMULATED	(1 << 0)

arch/riscv/kernel/sys_riscv.c

@@ -193,6 +193,7 @@ static void hwprobe_isa_ext0(struct riscv_hwprobe *pair,
 		if (has_fpu()) {
 			EXT_KEY(ZFH);
 			EXT_KEY(ZFHMIN);
+			EXT_KEY(ZFA);
 		}
 #undef EXT_KEY
 	}