[PATCH 3/3] target/mips: implement CP0.Config7.WII bit support

[Marcin Nowakowski]

Some older cores use CP0.Config7.WII bit to indicate that a disabled
interrupt should wake up a sleeping CPU.
Enable this bit by default for M14Kc, which supports that. There are
potentially other cores that support this feature, but I do not have a
complete list.

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@fungible.com>
---
 target/mips/cpu-defs.c.inc | 1 +
 target/mips/cpu.c          | 6 ++++--
 target/mips/cpu.h          | 1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/target/mips/cpu-defs.c.inc b/target/mips/cpu-defs.c.inc
index 480e60aeec..57856e2e72 100644
--- a/target/mips/cpu-defs.c.inc
+++ b/target/mips/cpu-defs.c.inc
@@ -354,6 +354,7 @@ const mips_def_t mips_defs[] =
                        (0 << CP0C1_DS) | (3 << CP0C1_DL) | (1 << CP0C1_DA),
         .CP0_Config2 = MIPS_CONFIG2,
         .CP0_Config3 = MIPS_CONFIG3 | (0x2 << CP0C3_ISA) | (0 << CP0C3_VInt),
+        .CP0_Config7 = 0x1 << CP0C7_WII,
         .CP0_LLAddr_rw_bitmask = 0,
         .CP0_LLAddr_shift = 4,
         .SYNCI_Step = 32,
diff --git a/target/mips/cpu.c b/target/mips/cpu.c
index 7a565466cb..7ba359696f 100644
--- a/target/mips/cpu.c
+++ b/target/mips/cpu.c
@@ -144,12 +144,14 @@ static bool mips_cpu_has_work(CPUState *cs)
     /*
      * Prior to MIPS Release 6 it is implementation dependent if non-enabled
      * interrupts wake-up the CPU, however most of the implementations only
-     * check for interrupts that can be taken.
+     * check for interrupts that can be taken. For pre-release 6 CPUs,
+     * check for CP0 Config7 'Wait IE ignore' bit.
      */
     if ((cs->interrupt_request & CPU_INTERRUPT_HARD) &&
         cpu_mips_hw_interrupts_pending(env)) {
         if (cpu_mips_hw_interrupts_enabled(env) ||
-            (env->insn_flags & ISA_MIPS_R6)) {
+            (env->insn_flags & ISA_MIPS_R6) ||
+            (env->CP0_Config7 & (1 << CP0C7_WII))) {
             has_work = true;
         }
     }
diff --git a/target/mips/cpu.h b/target/mips/cpu.h
index 0a085643a3..abee7a99d7 100644
--- a/target/mips/cpu.h
+++ b/target/mips/cpu.h
@@ -980,6 +980,7 @@ typedef struct CPUArchState {
 #define CP0C6_DATAPREF        0
     int32_t CP0_Config7;
     int64_t CP0_Config7_rw_bitmask;
+#define CP0C7_WII          31
 #define CP0C7_NAPCGEN       2
 #define CP0C7_UNIMUEN       1
 #define CP0C7_VFPUCGEN      0
-- 
2.25.1