Re: [Xen-devel] Kernel panic with tboot E820_UNUSABLE region

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

David Vrabel <david.vrabel@xxxxxxxxxx> wrote:

>On 14/05/13 15:46, Jan Beulich wrote:
>>>>> On 14.05.13 at 16:33, Aurelien Chartier
><aurelien.chartier@xxxxxxxxxx> wrote:
>> 
>> With
>> 
>>> (XEN)  0000000000100000 - 0000000000800000 (usable)
>>> (XEN)  0000000000800000 - 0000000000975000 (unusable)
>>> (XEN)  0000000000975000 - 0000000020000000 (usable)
>>> ...
>>> The region 0000000000975000 - 0000000020000000 has been set to
>unusable
>>> by tboot.
>> 
>> ... you certainly mean the range 800000-975000.
>> 
>>> Calls to update_va_mapping show the following error messages (with
>mfn
>>> going from 800 to 974):
>>>
>>> (XEN) mm.c:911:d0 Error getting mfn 800 (pfn 5555555555555555) from
>L1
>>> entry 0000000000800463 for l1e_owner=0, pg_owner=0
>> 
>> Yes, the kernel has no business mapping that region, and the
>> hypervisor rightly refuses the attempt.
>
>Ok, so this is Xen checking the new PTE supplied in the
>update_va_mapping hypercall and saying no.
>
>I think there are two things the kernel can do here.
>
>a) Change the type of UNUSABLE regions to RAM.
>
>b) Release pages overlapping UNUSABLE regions, destroy their mapping
>and
>clear/invalidate the region in the p2m.
>
>Option a) is probably the easiest.
>
>David

But option b) seems the proper one.
-- 
Sent from my Android phone. Please excuse my brevity.

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