[PATCH -next v13 07/19] riscv: Introduce riscv_vsize to record size of Vector context

[Andy Chiu <andy.chiu@xxxxxxxxxx>]

From: Greentime Hu <greentime.hu@xxxxxxxxxx>

This patch is used to detect the size of CPU vector registers and use
riscv_vsize to save the size of all the vector registers. It assumes all
harts has the same capabilities in a SMP system.

[guoren@xxxxxxxxxxxxxxxxx: add has_vector checking]
Co-developed-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Co-developed-by: Vincent Chen <vincent.chen@xxxxxxxxxx>
Signed-off-by: Vincent Chen <vincent.chen@xxxxxxxxxx>
Signed-off-by: Greentime Hu <greentime.hu@xxxxxxxxxx>
Signed-off-by: Andy Chiu <andy.chiu@xxxxxxxxxx>
---
 arch/riscv/include/asm/vector.h |  3 +++
 arch/riscv/kernel/cpufeature.c  | 12 +++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h
index 0fda0faf5277..16cb4a1c1230 100644
--- a/arch/riscv/include/asm/vector.h
+++ b/arch/riscv/include/asm/vector.h
@@ -13,6 +13,8 @@
 #include <asm/hwcap.h>
 #include <asm/csr.h>
 
+extern unsigned long riscv_vsize;
+
 static __always_inline bool has_vector(void)
 {
 	return static_branch_likely(&riscv_isa_ext_keys[RISCV_ISA_EXT_KEY_VECTOR]);
@@ -31,6 +33,7 @@ static __always_inline void rvv_disable(void)
 #else /* ! CONFIG_RISCV_ISA_V  */
 
 static __always_inline bool has_vector(void) { return false; }
+#define riscv_vsize (0)
 
 #endif /* CONFIG_RISCV_ISA_V */
 
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index c433899542ff..3aaae4e0b963 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -21,6 +21,7 @@
 #include <asm/processor.h>
 #include <asm/smp.h>
 #include <asm/switch_to.h>
+#include <asm/vector.h>
 
 #define NUM_ALPHA_EXTS ('z' - 'a' + 1)
 
@@ -31,6 +32,10 @@ static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
 
 DEFINE_STATIC_KEY_ARRAY_FALSE(riscv_isa_ext_keys, RISCV_ISA_EXT_KEY_MAX);
 EXPORT_SYMBOL(riscv_isa_ext_keys);
+#ifdef CONFIG_RISCV_ISA_V
+unsigned long riscv_vsize __read_mostly;
+EXPORT_SYMBOL_GPL(riscv_vsize);
+#endif
 
 /**
  * riscv_isa_extension_base() - Get base extension word
@@ -258,7 +263,12 @@ void __init riscv_fill_hwcap(void)
 	}
 
 	if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
-#ifndef CONFIG_RISCV_ISA_V
+#ifdef CONFIG_RISCV_ISA_V
+		/* There are 32 vector registers with vlenb length. */
+		rvv_enable();
+		riscv_vsize = csr_read(CSR_VLENB) * 32;
+		rvv_disable();
+#else
 		/*
 		 * ISA string in device tree might have 'v' flag, but
 		 * CONFIG_RISCV_ISA_V is disabled in kernel.
-- 
2.17.1