Re: [Xen-devel] [PATCH v4 12/17] xen/arm: ITS: Initialize LPI irq descriptors and route

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Vijay,

On 15/07/2015 20:13, Julien Grall wrote:
> > +uint8_t vgic_its_get_priority(struct vcpu *v, uint32_t pid)
> > +{
> > +    uint8_t priority;
> > +
> > +    priority =  readb_relaxed(v->domain->arch.vits->prop_page + pid);
> Why do you use readb_relaxed here? This should only be used for Device
> MMIO.
>
> Although, you need to ensure that the value will be correctly
> synchronize if another CPU is writing in prop_page which is protected by
> prop_lock.
I though a bit more during the night about this function. On patch #11, 
where you allocate prop_page, you allow to have a smaller table than the 
number of LPIs. If the pid is too high, even though valid, you may read 
Xen memory or even crash Xen.
Although, what does mean pid? Should not it be vlpi?

Regards,

--
Julien Grall

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