s390x: SMP for TCG

[Qemu-devel] [PATCH v2 09/30] s390x/tcg: handle WAIT PSWs during interrupt injection

Posted by David Hildenbrand 8 years, 4 months ago

If we encounter a WAIT PSW, we have to halt immediately. Using
cpu_loop_exit() at this point feels wrong. Simply leaving
cs->exception_index set doesn't result in an immediate stop.

This is also necessary to properly handle SIGP STOP interrupts later.

The CPU_INTERRUPT_HALT will be processed immediately and properly set
the CPU to halted (also resetting cs->exception_index to EXCP_HLT)

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 target/s390x/excp_helper.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
index f6747f3877..1a0d0770a9 100644
--- a/target/s390x/excp_helper.c
+++ b/target/s390x/excp_helper.c
@@ -467,6 +467,12 @@ void s390_cpu_do_interrupt(CPUState *cs)
         do_mchk_interrupt(env);
         break;
     }
+
+    /* WAIT PSW during interrupt injection */
+    if (cs->exception_index == EXCP_HLT) {
+        /* don't trigger a cpu_loop_exit(), use an interrupt instead */
+        cpu_interrupt(CPU(cpu), CPU_INTERRUPT_HALT);
+    }
     cs->exception_index = -1;
 
     /* we might still have pending interrupts, but not deliverable */
-- 
2.13.5

Re: [Qemu-devel] [PATCH v2 09/30] s390x/tcg: handle WAIT PSWs during interrupt injection

Posted by Richard Henderson 8 years, 4 months ago

On 09/28/2017 04:36 PM, David Hildenbrand wrote:
> If we encounter a WAIT PSW, we have to halt immediately. Using
> cpu_loop_exit() at this point feels wrong. Simply leaving
> cs->exception_index set doesn't result in an immediate stop.
> 
> This is also necessary to properly handle SIGP STOP interrupts later.
> 
> The CPU_INTERRUPT_HALT will be processed immediately and properly set
> the CPU to halted (also resetting cs->exception_index to EXCP_HLT)
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  target/s390x/excp_helper.c | 6 ++++++
>  1 file changed, 6 insertions(+)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~