[PATCH -next v20 05/26] riscv: Clear vector regfile on bootup

[Andy Chiu]

From: Greentime Hu <greentime.hu at sifive.com>

clear vector registers on boot if kernel supports V.

Signed-off-by: Greentime Hu <greentime.hu at sifive.com>
Signed-off-by: Vineet Gupta <vineetg at rivosinc.com>
Signed-off-by: Andy Chiu <andy.chiu at sifive.com>
Acked-by: Conor Dooley <conor.dooley at microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner at vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner at vrull.eu>
Reviewed-by: Palmer Dabbelt <palmer at rivosinc.com>
---
 arch/riscv/kernel/head.S | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 4bf6c449d78b..3fd6a4bd9c3e 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -392,7 +392,7 @@ ENTRY(reset_regs)
 #ifdef CONFIG_FPU
 	csrr	t0, CSR_MISA
 	andi	t0, t0, (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D)
-	beqz	t0, .Lreset_regs_done
+	beqz	t0, .Lreset_regs_done_fpu
 
 	li	t1, SR_FS
 	csrs	CSR_STATUS, t1
@@ -430,8 +430,31 @@ ENTRY(reset_regs)
 	fmv.s.x	f31, zero
 	csrw	fcsr, 0
 	/* note that the caller must clear SR_FS */
+.Lreset_regs_done_fpu:
 #endif /* CONFIG_FPU */
-.Lreset_regs_done:
+
+#ifdef CONFIG_RISCV_ISA_V
+	csrr	t0, CSR_MISA
+	li	t1, COMPAT_HWCAP_ISA_V
+	and	t0, t0, t1
+	beqz	t0, .Lreset_regs_done_vector
+
+	/*
+	 * Clear vector registers and reset vcsr
+	 * VLMAX has a defined value, VLEN is a constant,
+	 * and this form of vsetvli is defined to set vl to VLMAX.
+	 */
+	li	t1, SR_VS
+	csrs	CSR_STATUS, t1
+	csrs	CSR_VCSR, x0
+	vsetvli t1, x0, e8, m8, ta, ma
+	vmv.v.i v0, 0
+	vmv.v.i v8, 0
+	vmv.v.i v16, 0
+	vmv.v.i v24, 0
+	/* note that the caller must clear SR_VS */
+.Lreset_regs_done_vector:
+#endif /* CONFIG_RISCV_ISA_V */
 	ret
 END(reset_regs)
 #endif /* CONFIG_RISCV_M_MODE */
-- 
2.17.1