Re: [PATCH v3] xen/balloon: Mark unallocated host memory as UNUSABLE

From: Juergen Gross
Date: Wed Dec 20 2017 - 12:33:25 EST

On 20/12/17 15:05, Boris Ostrovsky wrote:
> Commit f5775e0b6116 ("x86/xen: discard RAM regions above the maximum
> reservation") left host memory not assigned to dom0 as available for
> memory hotplug.
> Unfortunately this also meant that those regions could be used by
> others. Specifically, commit fa564ad96366 ("x86/PCI: Enable a 64bit BAR
> on AMD Family 15h (Models 00-1f, 30-3f, 60-7f)") may try to map those
> addresses as MMIO.
> To prevent this mark unallocated host memory as E820_TYPE_UNUSABLE (thus
> effectively reverting f5775e0b6116) and keep track of that region as
> a hostmem resource that can be used for the hotplug.
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>