Re: [Xen-devel] [PATCH 15/22] xen/arm: Don't call p2m_alloc_table from arch_domain_create

[Julien Grall <julien.grall@xxxxxxx>]

On 22/07/16 11:39, Sergej Proskurin wrote:
> On 07/22/2016 12:26 PM, Julien Grall wrote:
> > On 22/07/16 11:16, Sergej Proskurin wrote:
> > > Hi Julien,
> > Hello,
> >
> > > On 07/22/2016 11:18 AM, Julien Grall wrote:
> > > > On 22/07/16 09:32, Sergej Proskurin wrote:
> > > > > Hi Julien,
> > > > Hello Sergej,
> > > >
> > > > > > -int p2m_alloc_table(struct domain *d)
> > > > > > +static int p2m_alloc_table(struct domain *d)
> > > > > While moving parts of the altp2m code out of ./xen/arch/arm/p2m.c, the
> > > > > function p2m_alloc_table needs to be called from
> > > > > ./xen/arch/arm/altp2m.c
> > > > > to allocate the individual altp2m views. Hence it should not be static.
> > > > No, this function should not be called outside p2m.c as it will not
> > > > fully initialize the p2m. You need to need to provide a function to
> > > > initialize a p2m (such as p2m_init).
> > > The last time we have discussed reusing existing code, among others, for
> > > individual struct p2m_domain initialization routines. Also, we have
> > > agreed to move altp2m-related parts out of p2m.c into altp2m.c, which
> > > makes it hard not to access parts required for initialization/teardown
> > > (that are equal for both p2m and altp2m).
> > I remember this discussion. However, the p2m initialize/teardown should
> > exactly be the same for the hostp2m and altp2m (except for the type of
> > the p2m). So, a function should be provided to initialize a full p2m to
> > avoid code duplication.
> This is exactly what has been done. Nevertheless, altp2m views are
> somewhat more dynamic than hostp2m and hence require frequent
> initialization/teardown of individual views. That is, by moving altp2m
> parts out of p2m.c we simply need to access this shared code multiple
> times at runtime from different altp2m-related functions. This applies
> to more functions that just to p2m_alloc_table.
I am not convinced that you need to reallocate the root page every time 
rather than clearing them. Anyway, I will need to see the code to 
understand what is done.
Regards,

--
Julien Grall

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