Re: [Xen-devel] Xen 4.5 random freeze question

[Andrii Tseglytskyi <andrii.tseglytskyi@xxxxxxxxxxxxxxx>]

Hi Stefano,



On Wed, Nov 19, 2014 at 4:52 PM, Stefano Stabellini
<stefano.stabellini@xxxxxxxxxxxxx> wrote:
> On Wed, 19 Nov 2014, Andrii Tseglytskyi wrote:
>> Hi Stefano,
>>
>> > >      if ( !list_empty(&current->arch.vgic.lr_pending) && lr_all_full() )
>> > > -        GICH[GICH_HCR] |= GICH_HCR_UIE;
>> > > +        GICH[GICH_HCR] |= GICH_HCR_NPIE;
>> > >      else
>> > > -        GICH[GICH_HCR] &= ~GICH_HCR_UIE;
>> > > +        GICH[GICH_HCR] &= ~GICH_HCR_NPIE;
>> > >
>> > >  }
>> >
>> > Yes, exactly
>>
>> I tried, hang still occurs with this change
>
> We need to figure out why during the hang you still have all the LRs
> busy even if you are getting maintenance interrupts that should cause
> them to be cleared.
>

I see that I have free LRs during maintenance interrupt

(XEN) gic.c:871:d0v0 maintenance interrupt
(XEN) GICH_LRs (vcpu 0) mask=0
(XEN)    HW_LR[0]=9a015856
(XEN)    HW_LR[1]=0
(XEN)    HW_LR[2]=0
(XEN)    HW_LR[3]=0
(XEN) Inflight irq=86 lr=0
(XEN) Inflight irq=2 lr=255
(XEN) Pending irq=2

But I see that after I got hang - maintenance interrupts are generated
continuously. Platform continues printing the same log till reboot.


My diff is on top of 394b7e587b05d0f4a5fd6f067b38339ab5a77121

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index b7516c0..1e0316a 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -66,7 +66,7 @@ static DEFINE_PER_CPU(u8, gic_cpu_id);
 /* Maximum cpu interface per GIC */
 #define NR_GIC_CPU_IF 8

-#undef GIC_DEBUG
+#define GIC_DEBUG 1

 static void gic_update_one_lr(struct vcpu *v, int i);

@@ -868,6 +868,8 @@ static void maintenance_interrupt(int irq, void
*dev_id, struct cpu_user_regs *r
      * on return to guest that is going to clear the old LRs and inject
      * new interrupts.
      */
+    gdprintk(XENLOG_DEBUG, "maintenance interrupt\n");
+    gic_dump_info(current);
 }

 void gic_dump_info(struct vcpu *v)


> Could you please call gic_dump_info(current) from maintenance_interrupt,
> and post the output during the hang? Remove the other gic_dump_info to
> avoid confusion, we want to understand what is the status of the LRs
> after clearing them upon receiving a maintenance interrupt at busy times.



-- 

Andrii Tseglytskyi | Embedded Dev
GlobalLogic
www.globallogic.com

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