Re: [Qemu-devel] [PATCH] Reworking MIPS interrupts handling

[Aurelien Jarno <aurelien@aurel32.net>]

On Tue, Jan 23, 2007 at 07:42:20PM +0100, Aurelien Jarno wrote:
> Hi all,
> 
> Please find below a patch to fix the IRQ issue on the MIPS platform. I
> have tested it on both 2.4 and 2.6 kernel and it works fine.
> 

Here is an updated patch including the comments from Paul Brook via IRC.
Thanks Paul for the review.


--- hw/mips_int.c	2007-01-18 20:37:29.623079789 +0100
+++ hw/mips_int.c	2007-01-23 20:55:13.000000000 +0100
@@ -0,0 +1,39 @@
+#include "vl.h"
+#include "cpu.h"
+
+/* Raise IRQ to CPU if necessary. It must be called every time the active
+   IRQ may change */
+void cpu_mips_update_irq(CPUState *env)
+{
+    if ((env->CP0_Status & env->CP0_Cause & CP0Ca_IP_mask) &&
+        (env->CP0_Status & (1 << CP0St_IE)) &&
+        !(env->hflags & MIPS_HFLAG_EXL) &&
+	!(env->hflags & MIPS_HFLAG_ERL) &&
+	!(env->hflags & MIPS_HFLAG_DM)) {
+        if (! (env->interrupt_request & CPU_INTERRUPT_HARD)) {
+            cpu_interrupt(env, CPU_INTERRUPT_HARD);
+	}
+    } else {
+        cpu_reset_interrupt(env, CPU_INTERRUPT_HARD);
+    }
+}
+
+void cpu_mips_irq_request(void *opaque, int irq, int level)
+{
+    CPUState *env = first_cpu;
+   
+    uint32_t mask;
+
+    if (irq >= 16)
+        return;
+
+    mask = 1 << (irq + CP0Ca_IP);
+
+    if (level) {
+        env->CP0_Cause |= mask;
+    } else {
+        env->CP0_Cause &= ~mask;
+    }
+    cpu_mips_update_irq(env);
+}
+
? hw/mips_int.c
Index: Makefile.target
===================================================================
RCS file: /sources/qemu/qemu/Makefile.target,v
retrieving revision 1.140
diff -u -d -p -r1.140 Makefile.target
--- Makefile.target	21 Jan 2007 22:40:04 -0000	1.140
+++ Makefile.target	23 Jan 2007 19:57:09 -0000
@@ -376,7 +376,7 @@ VL_OBJS+= grackle_pci.o prep_pci.o unin_
 CPPFLAGS += -DHAS_AUDIO
 endif
 ifeq ($(TARGET_ARCH), mips)
-VL_OBJS+= mips_r4k.o mips_malta.o mips_timer.o dma.o vga.o serial.o i8254.o i8259.o
+VL_OBJS+= mips_r4k.o mips_malta.o mips_timer.o mips_int.o dma.o vga.o serial.o i8254.o i8259.o
 VL_OBJS+= ide.o gt64xxx.o pckbd.o ps2.o fdc.o mc146818rtc.o usb-uhci.o acpi.o
 VL_OBJS+= piix_pci.o parallel.o mixeng.o cirrus_vga.o $(SOUND_HW) $(AUDIODRV)
 DEFINES += -DHAS_AUDIO
Index: cpu-exec.c
===================================================================
RCS file: /sources/qemu/qemu/cpu-exec.c,v
retrieving revision 1.88
diff -u -d -p -r1.88 cpu-exec.c
--- cpu-exec.c	7 Dec 2006 18:28:42 -0000	1.88
+++ cpu-exec.c	23 Jan 2007 19:57:10 -0000
@@ -535,7 +535,6 @@ int cpu_exec(CPUState *env1)
                         env->exception_index = EXCP_EXT_INTERRUPT;
                         env->error_code = 0;
                         do_interrupt(env);
-                        env->interrupt_request &= ~CPU_INTERRUPT_HARD;
 #if defined(__sparc__) && !defined(HOST_SOLARIS)
                         tmp_T0 = 0;
 #else
Index: vl.h
===================================================================
RCS file: /sources/qemu/qemu/vl.h,v
retrieving revision 1.175
diff -u -d -p -r1.175 vl.h
--- vl.h	21 Jan 2007 16:47:01 -0000	1.175
+++ vl.h	23 Jan 2007 19:57:10 -0000
@@ -1067,6 +1067,9 @@ extern QEMUMachine mips_machine;
 /* mips_malta.c */
 extern QEMUMachine mips_malta_machine;
 
+/* mips_int */
+extern void cpu_mips_irq_request(void *opaque, int irq, int level);
+
 /* mips_timer.c */
 extern void cpu_mips_clock_init(CPUState *);
 extern void cpu_mips_irqctrl_init (void);
Index: hw/gt64xxx.c
===================================================================
RCS file: /sources/qemu/qemu/hw/gt64xxx.c,v
retrieving revision 1.2
diff -u -d -p -r1.2 gt64xxx.c
--- hw/gt64xxx.c	17 Jan 2007 23:35:01 -0000	1.2
+++ hw/gt64xxx.c	23 Jan 2007 19:57:10 -0000
@@ -1,7 +1,7 @@
 /*
  * QEMU GT64120 PCI host
  *
- * Copyright (c) 2006 Aurelien Jarno
+ * Copyright (c) 2006,2007 Aurelien Jarno
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -433,7 +436,8 @@ static uint32_t gt64120_readl (void *opa
         val = s->regs[saddr];
         break;
     case GT_PCI0_IACK:
- 	val = pic_intack_read(isa_pic);
+        /* Read the IRQ number */ 
+        val = pic_read_irq(isa_pic);
         break;
 
     /* SDRAM Parameters */
Index: hw/i8259.c
===================================================================
RCS file: /sources/qemu/qemu/hw/i8259.c,v
retrieving revision 1.19
diff -u -d -p -r1.19 i8259.c
--- hw/i8259.c	25 Jun 2006 18:15:31 -0000	1.19
+++ hw/i8259.c	23 Jan 2007 19:57:10 -0000
@@ -161,6 +161,13 @@ void pic_update_irq(PicState2 *s)
 #endif
         s->irq_request(s->irq_request_opaque, 1);
     }
+
+/* all targets should do this rather than acking the IRQ in the cpu */
+#if defined(TARGET_MIPS)
+    else {
+        s->irq_request(s->irq_request_opaque, 0);
+    }
+#endif
 }
 
 #ifdef DEBUG_IRQ_LATENCY
Index: hw/mips_malta.c
===================================================================
RCS file: /sources/qemu/qemu/hw/mips_malta.c,v
retrieving revision 1.4
diff -u -d -p -r1.4 mips_malta.c
--- hw/mips_malta.c	20 Jan 2007 00:29:01 -0000	1.4
+++ hw/mips_malta.c	23 Jan 2007 19:57:10 -0000
@@ -54,16 +54,10 @@ typedef struct {
 
 static PITState *pit;
 
+/* The 8259 is attached to the MIPS CPU INT0 pin, ie interrupt 2 */
 static void pic_irq_request(void *opaque, int level)
 {
-    CPUState *env = first_cpu;
-    if (level) {
-        env->CP0_Cause |= 0x00000400;
-        cpu_interrupt(env, CPU_INTERRUPT_HARD);
-    } else {
-	env->CP0_Cause &= ~0x00000400;
-        cpu_reset_interrupt(env, CPU_INTERRUPT_HARD);
-    }
+    cpu_mips_irq_request(opaque, 2, level);
 }
 
 /* Malta FPGA */
Index: hw/mips_r4k.c
===================================================================
RCS file: /sources/qemu/qemu/hw/mips_r4k.c,v
retrieving revision 1.31
diff -u -d -p -r1.31 mips_r4k.c
--- hw/mips_r4k.c	6 Jan 2007 02:24:15 -0000	1.31
+++ hw/mips_r4k.c	23 Jan 2007 19:57:10 -0000
@@ -38,14 +38,7 @@ static PITState *pit; /* PIT i8254 */
 /*The PIC is attached to the MIPS CPU INT0 pin */
 static void pic_irq_request(void *opaque, int level)
 {
-    CPUState *env = first_cpu;
-    if (level) {
-        env->CP0_Cause |= 0x00000400;
-        cpu_interrupt(env, CPU_INTERRUPT_HARD);
-    } else {
-	env->CP0_Cause &= ~0x00000400;
-        cpu_reset_interrupt(env, CPU_INTERRUPT_HARD);
-    }
+    cpu_mips_irq_request(opaque, 2, level);
 }
 
 static void mips_qemu_writel (void *opaque, target_phys_addr_t addr,
Index: hw/mips_timer.c
===================================================================
RCS file: /sources/qemu/qemu/hw/mips_timer.c,v
retrieving revision 1.1
diff -u -d -p -r1.1 mips_timer.c
--- hw/mips_timer.c	6 Dec 2006 21:38:37 -0000	1.1
+++ hw/mips_timer.c	23 Jan 2007 19:57:10 -0000
@@ -57,8 +57,7 @@ void cpu_mips_store_count (CPUState *env
 void cpu_mips_store_compare (CPUState *env, uint32_t value)
 {
     cpu_mips_update_count(env, cpu_mips_get_count(env), value);
-    env->CP0_Cause &= ~0x00008000;
-    cpu_reset_interrupt(env, CPU_INTERRUPT_HARD);
+    cpu_mips_irq_request(env, 7, 0);
 }
 
 static void mips_timer_cb (void *opaque)
@@ -72,8 +71,7 @@ static void mips_timer_cb (void *opaque)
     }
 #endif
     cpu_mips_update_count(env, cpu_mips_get_count(env), env->CP0_Compare);
-    env->CP0_Cause |= 0x00008000;
-    cpu_interrupt(env, CPU_INTERRUPT_HARD);
+    cpu_mips_irq_request(env, 7, 1);
 }
 
 void cpu_mips_clock_init (CPUState *env)
Index: target-mips/cpu.h
===================================================================
RCS file: /sources/qemu/qemu/target-mips/cpu.h,v
retrieving revision 1.17
diff -u -d -p -r1.17 cpu.h
--- target-mips/cpu.h	22 Jan 2007 20:50:42 -0000	1.17
+++ target-mips/cpu.h	23 Jan 2007 19:57:10 -0000
@@ -157,6 +157,7 @@ struct CPUMIPSState {
 #define CP0Ca_IV   23
 #define CP0Ca_WP   22
 #define CP0Ca_IP    8
+#define CP0Ca_IP_mask 0x0000FF00
 #define CP0Ca_EC    2
     target_ulong CP0_EPC;
     uint32_t CP0_PRid;
Index: target-mips/exec.h
===================================================================
RCS file: /sources/qemu/qemu/target-mips/exec.h,v
retrieving revision 1.15
diff -u -d -p -r1.15 exec.h
--- target-mips/exec.h	3 Jan 2007 15:18:08 -0000	1.15
+++ target-mips/exec.h	23 Jan 2007 19:57:10 -0000
@@ -164,6 +164,7 @@ uint32_t cpu_mips_get_random (CPUState *
 uint32_t cpu_mips_get_count (CPUState *env);
 void cpu_mips_store_count (CPUState *env, uint32_t value);
 void cpu_mips_store_compare (CPUState *env, uint32_t value);
+void cpu_mips_update_irq(CPUState *env);
 void cpu_mips_clock_init (CPUState *env);
 void cpu_mips_tlb_flush (CPUState *env, int flush_global);
 
Index: target-mips/op.c
===================================================================
RCS file: /sources/qemu/qemu/target-mips/op.c,v
retrieving revision 1.19
diff -u -d -p -r1.19 op.c
--- target-mips/op.c	1 Jan 2007 20:35:21 -0000	1.19
+++ target-mips/op.c	23 Jan 2007 19:57:10 -0000
@@ -1351,7 +1351,7 @@ void op_mtc0_compare (void)
 
 void op_mtc0_status (void)
 {
-    uint32_t val, old, mask;
+    uint32_t val, old;
 
     val = T0 & (int32_t)0xFA78FF01;
     old = env->CP0_Status;
@@ -1368,21 +1368,9 @@ void op_mtc0_status (void)
     else
         env->hflags &= ~MIPS_HFLAG_EXL;
     env->CP0_Status = val;
-    /* If we unmasked an asserted IRQ, raise it */
-    mask = 0x0000FF00;
     if (loglevel & CPU_LOG_TB_IN_ASM)
        CALL_FROM_TB2(do_mtc0_status_debug, old, val);
-    if ((val & (1 << CP0St_IE)) && !(old & (1 << CP0St_IE)) &&
-        !(env->hflags & MIPS_HFLAG_EXL) &&
-        !(env->hflags & MIPS_HFLAG_ERL) &&
-        !(env->hflags & MIPS_HFLAG_DM) &&
-        (env->CP0_Status & env->CP0_Cause & mask)) {
-        env->interrupt_request |= CPU_INTERRUPT_HARD;
-       if (logfile)
-           CALL_FROM_TB0(do_mtc0_status_irqraise_debug);
-    } else if (!(val & (1 << CP0St_IE)) && (old & (1 << CP0St_IE))) {
-        env->interrupt_request &= ~CPU_INTERRUPT_HARD;
-    }
+    CALL_FROM_TB1(cpu_mips_update_irq, env);
     RETURN();
 }
 
@@ -1402,22 +1390,13 @@ void op_mtc0_srsctl (void)
 
 void op_mtc0_cause (void)
 {
-    uint32_t val, old;
+    env->CP0_Cause = (env->CP0_Cause & 0xB000F87C) | (T0 & 0x00C00300);
 
-    val = (env->CP0_Cause & 0xB000F87C) | (T0 & 0x00C00300);
-    old = env->CP0_Cause;
-    env->CP0_Cause = val;
-#if 0
-    {
-        int i, mask;
-       /* Check if we ever asserted a software IRQ */
-        for (i = 0; i < 2; i++) {
-            mask = 0x100 << i;
-            if ((val & mask) & !(old & mask))
-                CALL_FROM_TB1(mips_set_irq, i);
-        }
+    /* Handle the software interrupt as an hardware one, as they
+       are very similar */
+    if (T0 & CP0Ca_IP_mask) {
+        CALL_FROM_TB1(cpu_mips_update_irq, env);
     }
-#endif
     RETURN();
 }
 
@@ -1928,36 +1907,17 @@ void op_pmon (void)
 
 void op_di (void)
 {
-    uint32_t val;
-
     T0 = env->CP0_Status;
-    val = T0 & ~(1 << CP0St_IE);
-    if (val != T0) {
-        env->interrupt_request &= ~CPU_INTERRUPT_HARD;
-        env->CP0_Status = val;
-    }
+    env->CP0_Status = T0 & ~(1 << CP0St_IE);
+    CALL_FROM_TB1(cpu_mips_update_irq, env);
     RETURN();
 }
 
 void op_ei (void)
 {
-    uint32_t val;
-
     T0 = env->CP0_Status;
-    val = T0 | (1 << CP0St_IE);
-    if (val != T0) {
-       const uint32_t mask = 0x0000FF00;
-
-       env->CP0_Status = val;
-       if (!(env->hflags & MIPS_HFLAG_EXL) &&
-           !(env->hflags & MIPS_HFLAG_ERL) &&
-           !(env->hflags & MIPS_HFLAG_DM) &&
-           (env->CP0_Status & env->CP0_Cause & mask)) {
-               env->interrupt_request |= CPU_INTERRUPT_HARD;
-               if (logfile)
-                   CALL_FROM_TB0(do_mtc0_status_irqraise_debug);
-       }
-    }
+    env->CP0_Status = T0 | (1 << CP0St_IE);
+    CALL_FROM_TB1(cpu_mips_update_irq, env);
     RETURN();
 }
 
Index: target-mips/op_helper.c
===================================================================
RCS file: /sources/qemu/qemu/target-mips/op_helper.c,v
retrieving revision 1.26
diff -u -d -p -r1.26 op_helper.c
--- target-mips/op_helper.c	22 Jan 2007 20:50:42 -0000	1.26
+++ target-mips/op_helper.c	23 Jan 2007 19:57:10 -0000
@@ -265,6 +265,11 @@ void cpu_mips_store_compare(CPUState *en
     cpu_abort(env, "mtc0 compare\n");
 }
 
+void cpu_mips_update_irq(CPUState *env)
+{
+    cpu_abort(env, "mtc0 status / mtc0 cause\n");
+}
+
 void do_mtc0_status_debug(uint32_t old, uint32_t val)
 {
     cpu_abort(env, "mtc0 status debug\n");

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net