Re: [Xen-devel] [PATCH v4 2/4] xen/arm: inflight irqs during migration

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 06/11/2014 03:15 PM, Stefano Stabellini wrote:
>>> +        {
>>> +            unsigned int irq, target, old_target;
>>> +            struct vcpu *v_target, *v_old;
>>> +
>>> +            target = i % 8;
>>> +
>>> +            irq = offset + (i / 8);
>>> +            v_target = v->domain->vcpu[target];
>>> +            old_target = byte_read(rank->itargets[REG_RANK_INDEX(8, 
>>> gicd_reg - GICD_ITARGETSR)], 0, i/8);
>>> +            v_old = v->domain->vcpu[old_target];
>>
>> v_target and v_old might be the same.
> 
> No, they could not: if they were find_next_bit wouldn't find the bit set.

Even though v_target is always != v_old (because of the tr = r & ~val
stuff), why do you migrate if the old_target will be in the new mask?

BTW, this code suffers the same issue as #1, i.e this register can be
accessed by byte.

Regards,

-- 
Julien Grall

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