[PATCH v1 09/21] target/m68k: add BQL to do_interrupt and cpu_exec_interrupt

[Robert Foley]

This is part of a series of changes to remove the implied BQL
from the common code of cpu_handle_interrupt and
cpu_handle_exception.  As part of removing the implied BQL
from the common code, we are pushing the BQL holding
down into the per-arch implementation functions of
do_interrupt and cpu_exec_interrupt.

The purpose of this set of changes is to set the groundwork
so that an arch could move towards removing
the BQL from the cpu_handle_interrupt/exception paths.

This approach was suggested by Paolo Bonzini.
For reference, here are two key posts in the discussion, explaining
the reasoning/benefits of this approach.
https://lists.gnu.org/archive/html/qemu-devel/2020-07/msg08731.html
https://lists.gnu.org/archive/html/qemu-devel/2020-08/msg00044.html

Signed-off-by: Robert Foley <robert.foley@linaro.org>
---
 target/m68k/op_helper.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c
index 4a032a150e..0c3333476a 100644
--- a/target/m68k/op_helper.c
+++ b/target/m68k/op_helper.c
@@ -448,7 +448,9 @@ void m68k_cpu_do_interrupt(CPUState *cs)
     M68kCPU *cpu = M68K_CPU(cs);
     CPUM68KState *env = &cpu->env;
 
+    qemu_mutex_lock_iothread();
     do_interrupt_all(env, 0);
+    qemu_mutex_unlock_iothread();
 }
 
 static inline void do_interrupt_m68k_hardirq(CPUM68KState *env)
@@ -508,6 +510,7 @@ bool m68k_cpu_exec_interrupt(CPUState *cs, int 
interrupt_request)
 {
     M68kCPU *cpu = M68K_CPU(cs);
     CPUM68KState *env = &cpu->env;
+    qemu_mutex_lock_iothread();
 
     if (interrupt_request & CPU_INTERRUPT_HARD
         && ((env->sr & SR_I) >> SR_I_SHIFT) < env->pending_level) {
@@ -519,8 +522,10 @@ bool m68k_cpu_exec_interrupt(CPUState *cs, int 
interrupt_request)
          */
         cs->exception_index = env->pending_vector;
         do_interrupt_m68k_hardirq(env);
+        qemu_mutex_unlock_iothread();
         return true;
     }
+    qemu_mutex_unlock_iothread();
     return false;
 }
 
-- 
2.17.1