riscv: vector: use a mask to write vstate_ctrl

riscv_v_ctrl_set() should only touch bits within
PR_RISCV_V_VSTATE_CTRL_MASK. So, use the mask when we really set task's
vstate_ctrl.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240115055929.4736-9-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c
index 66e8c6ab09d257c8f50cd8d966c1ac7e0b2a1517..c1f28bc89ec64b8973c12330fe40cab3d79e304a 100644 (file)
--- a/arch/riscv/kernel/vector.c
+++ b/arch/riscv/kernel/vector.c
@@ -122,7 +122,8 @@ static inline void riscv_v_ctrl_set(struct task_struct *tsk, int cur, int nxt,
        ctrl |= VSTATE_CTRL_MAKE_NEXT(nxt);
        if (inherit)
                ctrl |= PR_RISCV_V_VSTATE_CTRL_INHERIT;
-       tsk->thread.vstate_ctrl = ctrl;
+       tsk->thread.vstate_ctrl &= ~PR_RISCV_V_VSTATE_CTRL_MASK;
+       tsk->thread.vstate_ctrl |= ctrl;
 }
 
 bool riscv_v_vstate_ctrl_user_allowed(void)