On 14/06/2017 17:45, Richard Henderson wrote:
> While the next TB would detect the exit flag has been set there is no
> point if we can exit sooner. We also check cpu->interrupt_request as
> some front-ends can set it rather than using the cpu_interrupt() API
> call and would normally be expecting the IRQ to get picked up on the
> previously fairly regular exits from the run loop.
This is not what happens actually; it's not about front-ends setting
cpu->interrupt_request, it's about front-ends doing exit_tb when they
wanted to re-evaluate cpu_handle_interrupt.
cpu_exit is used when device code causes a rising edge in
cpu->interrupt_request. What we have here is that the MSR write causes
cc->cpu_exec_interrupt's return value to change from false to true.
I think this is a band-aid, and would rather fix the front-ends as in
Emilio's patch. For Alpha my guess would be:
diff --git a/target/alpha/translate.c b/target/alpha/translate.c
index 7c45ae360c..6e2ee3f958 100644
--- a/target/alpha/translate.c
+++ b/target/alpha/translate.c
@@ -1198,7 +1198,9 @@ static ExitStatus gen_call_pal(DisasContext *ctx, int
palcode)
tcg_gen_andi_i64(tmp, ctx->ir[IR_A0], PS_INT_MASK);
tcg_gen_st8_i64(tmp, cpu_env, offsetof(CPUAlphaState, ps));
tcg_temp_free(tmp);
- break;
+
+ /* Reevaluate interrupts */
+ return EXIT_PC_STALE;
case 0x36:
/* RDPS */
It's okay as a last resort I guess, but there's still a lot of
time before 2.9.
Paolo
