Re: [Qemu-devel] [PATCH v1 3/3] tcg-runtime: short-circuit lookup_tb_ptr on IRQs

[Paolo Bonzini <pbonzini@redhat.com>]

On 14/06/2017 18:51, Richard Henderson wrote:
> On 06/14/2017 09:08 AM, Paolo Bonzini wrote:
>> 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 */
> 
> Thanks!
> 
> You're right that adjusting SWPIPL along these lines does fix the
> problem for Alpha.  Given that Alpha would typically hang in arch_idle,
> I'd been focusing primarily on WTINT.

And MIPS:

diff --git a/target/mips/translate.c b/target/mips/translate.c
index 559f8fed89..244f3cb9ab 100644
--- a/target/mips/translate.c
+++ b/target/mips/translate.c
@@ -13403,8 +13403,9 @@ static void gen_pool32axf (CPUMIPSState *env, DisasContext *ctx, int rt, int rs)
                 save_cpu_state(ctx, 1);
                 gen_helper_ei(t0, cpu_env);
                 gen_store_gpr(t0, rs);
-                /* Stop translation as we may have switched the execution mode */
-                ctx->bstate = BS_STOP;
+                /* BS_STOP isn't good enough here, reevaluate cpu_mips_hw_interrupts_enabled. */
+                gen_save_pc(ctx->pc + 4);
+                ctx->bstate = BS_EXCP;
                 tcg_temp_free(t0);
             }
             break;

The others seem okay.

Paolo