Re: [Xen-devel] reserve e820 ram

[Tim Deegan <tim@xxxxxxx>]

At 15:36 +0100 on 18 Apr (1334763404), Francisco Rocha wrote:
> Hi Tim,
> 
> I was thinking about changing my approach.
> 
> I think that for now I will leave those pages off because I am
> mostly interested in protecting other areas.
> 
> Those accesses for now are inevitable to get the VM to properly
> operate. Now, the question is if it is possible to use page table
> entries to do what I want to do.
> 
> The objective would be to use a bit flag that would determine if
> the pages are returned when a call to map_foreign_range is made.
> So, my final objective would be that only pages used for the three
> operations you describe are accessible to Dom0.
> Everything that is not BIOS and related, Qemu or PV backend
> drivers will not be returned.
> 
> From what I see in the header files you use 12-bits from a 24-bit
> flag (x86_64). Can we do it? This would again take us to controlling
> access at get_page_from_l1e(), right?

Are you talking about the count_info and type_info fields?  yes, I think
you can probably put a new flag or two in there.  Choosing which pages
qemu can map will be interesting, though -- it needs to map anything the
VM uses for I/O.  But maybe you can just define the things you protect
and declare taht they can't be used for I/O.  That sounds easier. :)

Cheers,

Tim.



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