[PATCH v2 3/7] target/cris: add CRISCPUClass->do_interrupt_locked

[Robert Foley <robert.foley@linaro.org>]

Adding ->do_interrupt_locked to CRISCPUClass is preparation for
pushing the BQL down into the per-arch implementation of ->do_interrupt.

This is needed since Cris's *_cpu_exec_interrupt calls to *_do_interrupt.
With the push down of the BQL into *_cpu_exec_interrupt and
*_do_interrupt, *_cpu_exec_interrupt will call to ->do_interrupt
with lock held.  Since ->do_interrupt also has the lock, we need a way
to allow cpu_exec_interrupt to call do_interrupt with lock held.
This patch solves the issue of *_cpu_exec_interrupt needing
to call do_interrupt with lock held.

This patch is part of a series of transitions to move the
BQL down into the do_interrupt per arch functions.  This set of
transitions is needed to maintain bisectability.

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/2020-08/msg00784.html
https://lists.gnu.org/archive/html/qemu-devel/2020-08/msg01517.html
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/cris/cpu-qom.h | 3 +++
 target/cris/cpu.c     | 6 ++++++
 target/cris/helper.c  | 6 +++---
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/target/cris/cpu-qom.h b/target/cris/cpu-qom.h
index f1de6041dc..dc94a17ffe 100644
--- a/target/cris/cpu-qom.h
+++ b/target/cris/cpu-qom.h
@@ -36,6 +36,7 @@
  * @parent_realize: The parent class' realize handler.
  * @parent_reset: The parent class' reset handler.
  * @vr: Version Register value.
+ * @do_interrupt_locked: Handler for interrupts (lock already held).
  *
  * A CRIS CPU model.
  */
@@ -48,6 +49,8 @@ typedef struct CRISCPUClass {
     DeviceReset parent_reset;
 
     uint32_t vr;
+
+    void (*do_interrupt_locked)(CPUState *cpu);
 } CRISCPUClass;
 
 typedef struct CRISCPU CRISCPU;
diff --git a/target/cris/cpu.c b/target/cris/cpu.c
index 40b110f161..948eeb6260 100644
--- a/target/cris/cpu.c
+++ b/target/cris/cpu.c
@@ -200,6 +200,7 @@ static void crisv8_cpu_class_init(ObjectClass *oc, void *data)
 
     ccc->vr = 8;
     cc->do_interrupt = crisv10_cpu_do_interrupt_locked;
+    ccc->do_interrupt_locked = crisv10_cpu_do_interrupt_locked;
     cc->gdb_read_register = crisv10_cpu_gdb_read_register;
     cc->tcg_initialize = cris_initialize_crisv10_tcg;
 }
@@ -211,6 +212,7 @@ static void crisv9_cpu_class_init(ObjectClass *oc, void *data)
 
     ccc->vr = 9;
     cc->do_interrupt = crisv10_cpu_do_interrupt_locked;
+    ccc->do_interrupt_locked = crisv10_cpu_do_interrupt_locked;
     cc->gdb_read_register = crisv10_cpu_gdb_read_register;
     cc->tcg_initialize = cris_initialize_crisv10_tcg;
 }
@@ -222,6 +224,7 @@ static void crisv10_cpu_class_init(ObjectClass *oc, void *data)
 
     ccc->vr = 10;
     cc->do_interrupt = crisv10_cpu_do_interrupt_locked;
+    ccc->do_interrupt_locked = crisv10_cpu_do_interrupt_locked;
     cc->gdb_read_register = crisv10_cpu_gdb_read_register;
     cc->tcg_initialize = cris_initialize_crisv10_tcg;
 }
@@ -233,6 +236,7 @@ static void crisv11_cpu_class_init(ObjectClass *oc, void *data)
 
     ccc->vr = 11;
     cc->do_interrupt = crisv10_cpu_do_interrupt_locked;
+    ccc->do_interrupt_locked = crisv10_cpu_do_interrupt_locked;
     cc->gdb_read_register = crisv10_cpu_gdb_read_register;
     cc->tcg_initialize = cris_initialize_crisv10_tcg;
 }
@@ -244,6 +248,7 @@ static void crisv17_cpu_class_init(ObjectClass *oc, void *data)
 
     ccc->vr = 17;
     cc->do_interrupt = crisv10_cpu_do_interrupt_locked;
+    ccc->do_interrupt_locked = crisv10_cpu_do_interrupt_locked;
     cc->gdb_read_register = crisv10_cpu_gdb_read_register;
     cc->tcg_initialize = cris_initialize_crisv10_tcg;
 }
@@ -269,6 +274,7 @@ static void cris_cpu_class_init(ObjectClass *oc, void *data)
     cc->class_by_name = cris_cpu_class_by_name;
     cc->has_work = cris_cpu_has_work;
     cc->do_interrupt = cris_cpu_do_interrupt_locked;
+    ccc->do_interrupt_locked = cris_cpu_do_interrupt_locked;
     cc->cpu_exec_interrupt = cris_cpu_exec_interrupt;
     cc->dump_state = cris_cpu_dump_state;
     cc->set_pc = cris_cpu_set_pc;
diff --git a/target/cris/helper.c b/target/cris/helper.c
index e0ee6b4e05..3b7ee74813 100644
--- a/target/cris/helper.c
+++ b/target/cris/helper.c
@@ -290,7 +290,7 @@ hwaddr cris_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
 
 bool cris_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
 {
-    CPUClass *cc = CPU_GET_CLASS(cs);
+    CRISCPUClass *ccc = CRIS_CPU_CLASS(cs);
     CRISCPU *cpu = CRIS_CPU(cs);
     CPUCRISState *env = &cpu->env;
     bool ret = false;
@@ -299,7 +299,7 @@ bool cris_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
         && (env->pregs[PR_CCS] & I_FLAG)
         && !env->locked_irq) {
         cs->exception_index = EXCP_IRQ;
-        cc->do_interrupt(cs);
+        ccc->do_interrupt_locked(cs);
         ret = true;
     }
     if (interrupt_request & CPU_INTERRUPT_NMI) {
@@ -311,7 +311,7 @@ bool cris_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
         }
         if ((env->pregs[PR_CCS] & m_flag_archval)) {
             cs->exception_index = EXCP_NMI;
-            cc->do_interrupt(cs);
+            ccc->do_interrupt_locked(cs);
             ret = true;
         }
     }
-- 
2.17.1