Re: [Xen-devel] [PATCH v3 08/10] xen/arm: Release timer interrupts when CPU is hot-unplugged

[Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>]

Hi Julien,

On Mon, Apr 30, 2018 at 5:58 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hi,
>
>
> On 27/04/18 18:12, Mirela Simonovic wrote:
>>
>> When a CPU is hot-unplugged timer interrupts have to be released
>> in order to free the memory that was allocated when the interrupts
>> were requested (using request_irq()). The request_irq is called
>> for each timer interrupt when the CPU gets hotplugged
>> (start_secondary->init_timer_interrupt->request_irq).
>> With this patch the timer interrupts will be released when the
>> newly added callback receives CPU_DYING event.
>>
>> Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
>>
>> ---
>> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> CC: Julien Grall <julien.grall@xxxxxxx>
>> ---
>> Changes in v3:
>> -Trigger releasing of timer interrupts using notifiers
>> ---
>>   xen/arch/arm/time.c | 39 +++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 39 insertions(+)
>>
>> diff --git a/xen/arch/arm/time.c b/xen/arch/arm/time.c
>> index c11fcfeadd..c7317e4639 100644
>> --- a/xen/arch/arm/time.c
>> +++ b/xen/arch/arm/time.c
>> @@ -29,6 +29,8 @@
>>   #include <xen/sched.h>
>>   #include <xen/event.h>
>>   #include <xen/acpi.h>
>> +#include <xen/notifier.h>
>> +#include <xen/cpu.h>
>>   #include <asm/system.h>
>>   #include <asm/time.h>
>>   #include <asm/vgic.h>
>> @@ -312,6 +314,17 @@ void init_timer_interrupt(void)
>>       check_timer_irq_cfg(timer_irq[TIMER_PHYS_NONSECURE_PPI],
>> "NS-physical");
>>   }
>>   +/*
>> + * Revert actions done in init_timer_interrupt that are required to
>> properly
>> + * disable this CPU.
>> + */
>> +static void deinit_timer_interrupt(void)
>> +{
>
>
> Any reason to not disable the timer here? But I think we need to finish the
> discussion on the previous series regarding the purpose of the mdelay before
> going further with that patch. See patch v2 7/10. I would also appreciate
> answer to my question there.
>

I just missed it. Will add disabling timers.

>
>> +    release_irq(timer_irq[TIMER_HYP_PPI], NULL);
>> +    release_irq(timer_irq[TIMER_VIRT_PPI], NULL);
>> +    release_irq(timer_irq[TIMER_PHYS_NONSECURE_PPI], NULL);
>> +}
>> +
>>   /* Wait a set number of microseconds */
>>   void udelay(unsigned long usecs)
>>   {
>> @@ -340,6 +353,32 @@ void domain_set_time_offset(struct domain *d, int64_t
>> time_offset_seconds)
>>       /* XXX update guest visible wallclock time */
>>   }
>>   +static int cpu_time_callback(
>> +    struct notifier_block *nfb, unsigned long action, void *hcpu)
>> +{
>> +    switch ( action )
>> +    {
>> +    case CPU_DYING:
>> +        deinit_timer_interrupt();
>> +        break;
>> +    default:
>> +        break;
>> +    }
>> +
>> +    return NOTIFY_DONE;
>> +}
>> +
>> +static struct notifier_block cpu_time_nfb = {
>> +    .notifier_call = cpu_time_callback,
>> +};
>> +
>> +static int __init cpu_time_notifier_init(void)
>> +{
>> +    register_cpu_notifier(&cpu_time_nfb);
>> +    return 0;
>> +}
>> +__initcall(cpu_time_notifier_init);
>> +
>>   /*
>>    * Local variables:
>>    * mode: C
>>
>
> Cheers,
>
> --
> Julien Grall


Thanks,
Mirela

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel