linux-kernel - [RFC PATCH v8 06/21] riscv: Add has_vector/riscv

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Message-Id: <05f277fa32f74cefc76a8171abd7430e772753e3.1631121222.git.greentime.hu@sifive.com>
Date:   Thu,  9 Sep 2021 01:45:18 +0800
From:   Greentime Hu <greentime.hu@...ive.com>
To:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        aou@...s.berkeley.edu, palmer@...belt.com,
        paul.walmsley@...ive.com, vincent.chen@...ive.com
Subject: [RFC PATCH v8 06/21] riscv: Add has_vector/riscv_vsize to save vector features.

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

[guoren@...ux.alibaba.com: add has_vector checking]
Signed-off-by: Greentime Hu <greentime.hu@...ive.com>
Co-developed-by: Guo Ren <guoren@...ux.alibaba.com>
Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Co-developed-by: Vincent Chen <vincent.chen@...ive.com>
Signed-off-by: Vincent Chen <vincent.chen@...ive.com>
---
 arch/riscv/kernel/cpufeature.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 7069e55335d0..7265d947d981 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -21,6 +21,10 @@ static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
 #ifdef CONFIG_FPU
 __ro_after_init DEFINE_STATIC_KEY_FALSE(cpu_hwcap_fpu);
 #endif
+#ifdef CONFIG_VECTOR
+bool has_vector __read_mostly;
+unsigned long riscv_vsize __read_mostly;
+#endif
 
 /**
  * riscv_isa_extension_base() - Get base extension word
@@ -149,4 +153,12 @@ void __init riscv_fill_hwcap(void)
 	if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
 		static_branch_enable(&cpu_hwcap_fpu);
 #endif
+
+#ifdef CONFIG_VECTOR
+	if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
+		has_vector = true;
+		/* There are 32 vector registers with vlenb length. */
+		riscv_vsize = csr_read(CSR_VLENB) * 32;
+	}
+#endif
 }
-- 
2.31.1