Re: [PATCH] hvm: handle PoD and grant pages in HVMOP_get_mem_type

[Olaf Hering <olaf@aepfle.de>]

On Fri, Oct 19, Andres Lagar-Cavilla wrote:

> > +            else if ( p2m_is_magic(t) )
> > +                a.mem_type =  HVMMEM_ram_rw;
> p2m_is_magic is this bizarre thing that should just be p2m_is_pod. Can
> you take advantage of this opportunity and fix it?

I will prepare a separate patch for that rename.

> > +            else if ( p2m_is_grant(t) )
> > +                a.mem_type =  HVMMEM_ram_rw;
> 
> Yes there can be p2m_is_grant pages in an HVM, if it is running a
> backend. Note that you need to discriminate whether the grant is
> mapped writable in order to return ram_rw or ram_ro.

I will put p2m_grant_map_rw into HVMMEM_ram_rw, and p2m_grant_map_ro
into HVMMEM_ram_ro.

> It might be a good idea to extend this interface to return
> HVMMEM_grant_rw/ro. These are, in essence, different types of ram from
> an HVM point of view. However, it might be overkill for the current
> users.

Would the guest really care about the info that a given page is a grant
page? What would it do with that info?


Olaf