Re: [Xen-devel] [PATCH] xen/setup: Don't relocate p2m/initrd over existing one

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

On 12/12/2016 08:19 AM, Juergen Gross wrote:
> On 09/12/16 16:50, Ross Lagerwall wrote:
> > When relocating the p2m/initrd, take special care not to relocate it so
> > that is overlaps with the current location of the p2m/initrd. This is
> > needed since the full extent of the current location is not marked as a
> > reserved region in the e820 (and it shouldn't be since it is about to be
> > moved).
> >
> > This was seen to happen to a dom0 with a large initial p2m and a small
> > reserved region in the middle of the initial p2m.
> >
> > Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> Wouldn't it be more natural to memblock_reserve() the hypervisor
> supplied p2m list even in case of an E820 conflict and do a
> memblock_free() of that region after moving the p2m list in
> xen_relocate_p2m() ?
>
> This would avoid the need to supply a range to avoid for memory
> allocation when calling xen_find_free_area(), which is pointless in the
> initrd case (the original initrd area is already reserved via
> memblock_reserve() ).
I'm not familiar with the code, but I was concerned that if part of the 
hypervisor-supplied p2m was already reserved by memblock_reserve(), then 
the above approach would remove it when memblock_free is called. If this 
is not a valid concern, then I can send a patch to do it.
--
Ross Lagerwall

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