Re: [Xen-devel] [PATCH v2 10/21] xen/arm: Implement hypercall PHYSDEVOP_{, un}map_pirq

[Andrii Tseglytskyi <andrii.tseglytskyi@xxxxxxxxxxxxxxx>]

Hi Julien,


On Fri, Aug 29, 2014 at 10:08 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
>
>
> On 29/08/14 08:34, Andrii Tseglytskyi wrote:
>>
>> Hi Julien,
>
>
> Hi Andrii,
>
>
>>> +static int physdev_map_pirq(domid_t domid, int type, int index, int
>>> *pirq_p)
>>> +{
>>> +    struct domain *d;
>>> +    int ret;
>>> +    int irq = index;
>>> +    int virq = 0;
>>> +
>>> +    d = rcu_lock_domain_by_any_id(domid);
>>> +    if ( d == NULL )
>>> +        return -ESRCH;
>>> +
>>> +    ret = xsm_map_domain_pirq(XSM_TARGET, d);
>>> +    if ( ret )
>>> +        goto free_domain;
>>> +
>>> +    /* For now we only suport GSI */
>>> +    if ( type != MAP_PIRQ_TYPE_GSI )
>>> +    {
>>> +        ret = -EINVAL;
>>> +        dprintk(XENLOG_G_ERR, "dom%u: wrong map_pirq type 0x%x\n",
>>> +                d->domain_id, type);
>>> +        goto free_domain;
>>> +    }
>>> +
>>> +    if ( !is_assignable_irq(irq) )
>>> +    {
>>> +        ret = -EINVAL;
>>> +        dprintk(XENLOG_G_ERR, "IRQ%u is not routable to a guest\n",
>>> irq);
>>> +        goto free_domain;
>>> +    }
>>> +
>>> +    ret = -EPERM;
>>> +    if ( !irq_access_permitted(current->domain, irq) )
>>> +        goto free_domain;
>>
>>
>> I have a question here. This code is executed when dom0 creates domU.
>> current->domain points to dom0 here, in other words access to IRQ must
>> be permitted for dom0. Right ?
>> But in this case following call of route_irq_to_guest() fails with
>> message:
>>
>> (XEN) irq.c:459: IRQ 53 is already used by domain 0
>>
>> I reproduced this in the following steps:
>> - define IRQ in device tree, which is used by dom0, as result IRQ is
>> mapped to dom0
>> - after I defined it in domU configuration file, tried to launch domU
>> and got this error
>>
>> What I'm doing wrong here?
>
>
> PHYSDEVOP_map_pirq can assign an IRQ to a domain if it's free.
>
> My series is assuming that the device is not used by anyone (status =
> "disabled" property in the device tree node).
>
> In general, a device should not be shared between domains. If you need to
> use it at boot in DOM0, for now, you will have to disable the drivers and
> unmap every IRQ (see PHYSDEVOP_unmap_irq).
>

Do you mean, that status=disabled in device tree will be enough to
pass irq_access_permitted(current->domain, irq) check ?
I don't need to share devices between domains and I don't need to have
these IRQs in dom0. I'm just trying to figure out how
to pass irq_access_permitted() check. Because I took a look inside it
and see that it checks rangeset, which may be added only by
irq_permit_access(). And I suppose that this call provides exclusive
access to IRQ for selected domain.

>
>>> +
>>> +    virq = vgic_allocate_virq(d, irq);
>>> +    ret = -EMFILE;
>>> +    if ( virq == -1 )
>>> +        goto free_domain;
>>> +
>>> +    ret = route_irq_to_guest(d, virq, irq, "routed IRQ");
>>> +
>>
>>
>> This call fails for me with the message:
>>
>> (XEN) irq.c:440: IRQ 53 has not been configured.
>>
>> Locally I added the following code, which sets IRQ type:
>>
>> diff --git a/xen/arch/arm/physdev.c b/xen/arch/arm/physdev.c
>> index 9333aa0..e853e80 100644
>> --- a/xen/arch/arm/physdev.c
>> +++ b/xen/arch/arm/physdev.c
>> @@ -55,6 +55,7 @@ static int physdev_map_pirq(domid_t domid, int type,
>> int index, int *pirq_p)
>>       if ( virq == -1 )
>>           goto free_domain;
>>
>> +    irq_set_spi_type(irq, DT_IRQ_TYPE_LEVEL_MASK);
>>       ret = route_irq_to_guest(d, virq, irq, "routed IRQ");
>>
>>       if ( !ret )
>>
>>
>> Should it be added, or I need to do this in a different way - some
>> extra options for IRQ in config file, or something else?
>
>
> At boot Xen is browsing the device tree to configure every IRQ. Does you IRQ
> describe in the device tree?
>

This is related to previous comment. If I describe IRQ in device tree
- it is assigned exclusively to dom0.
If I don't describe it - I need to set it type here.

> Regards,
>
> --
> Julien Grall



-- 

Andrii Tseglytskyi | Embedded Dev
GlobalLogic
www.globallogic.com

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