Re: [Xen-devel] [V9 PATCH 6/8] pvh dom0: Add and remove foreign pages

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.04.14 at 04:09, <mukesh.rathor@xxxxxxxxxx> wrote:
> Ok, how about something like shown further below?  (I think
> it would be more simpler to have one atomic_write ops, instead of two)

That's an understandable desire, but ...

> +/* returns : 0 for success, -errno otherwise */
> +static int atomic_write_ept_entry(ept_entry_t *entryptr, ept_entry_t new)
> +{
> +    unsigned long oldmfn;
> +    struct domain *fdom;
> +    bool_t new_foreign = p2m_is_foreign(new.sa_p2mt);
> +    bool_t old_foreign = p2m_is_foreign(entryptr->sa_p2mt);

... these aren't really valid for intermediate entries (they just end up
getting p2m_ram_rw put into them right now, but that's in no way
explicit, and hence not set in stone). As said before, I can see the
need to use these fields eventually, so this would end up being a
latent problem. Hence minimally I'd want you to explicitly set the
field in ept_set_middle_entry() to make clear that we now depend on
it having a certain value.

Jan


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