target/mips: Set CP0St_{KX, SX, UX} for Loongson-2F

As per an unpublished document, in later reversion of chips
CP0St_{KX, SX, UX} is not writeable and hardcoded to 1.

Without those bits set, kernel is unable to access XKPHYS address
segment. So just set them up on CPU reset.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221031132531.18122-2-jiaxun.yang@flygoat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

diff --git a/target/mips/cpu.c b/target/mips/cpu.c
index e997c1b9cb1d3f3efc5a0f6ffbea1d66cba761b8..7a565466cb3fed3c5f0997439ce032976dab9a89 100644 (file)
--- a/target/mips/cpu.c
+++ b/target/mips/cpu.c
@@ -302,6 +302,12 @@ static void mips_cpu_reset(DeviceState *dev)
     env->CP0_EntryHi_ASID_mask = (env->CP0_Config5 & (1 << CP0C5_MI)) ?
             0x0 : (env->CP0_Config4 & (1 << CP0C4_AE)) ? 0x3ff : 0xff;
     env->CP0_Status = (1 << CP0St_BEV) | (1 << CP0St_ERL);
+    if (env->insn_flags & INSN_LOONGSON2F) {
+        /* Loongson-2F has those bits hardcoded to 1 */
+        env->CP0_Status |= (1 << CP0St_KX) | (1 << CP0St_SX) |
+                            (1 << CP0St_UX);
+    }
+
     /*
      * Vectored interrupts not implemented, timer on int 7,
      * no performance counters.