Re: [Xen-devel] Is: EPT violations. Was:Re: Problems with pci/vga passthrough

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 01/24/2017 01:44 PM, Diederik de Haas wrote:
> On dinsdag 24 januari 2017 13:28:28 CET Boris Ostrovsky wrote:
>>>> Reported it at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=852324
>>>> but  given Ben Hutchings' reaction it seems to be a Xen problem after
>>>> all.
>>>>
>>>> Relevant part of earlier attached dmesg:
>>>>
>>>> [   13.588386] WARNING: CPU: 18 PID: 1 at 
>>>> /build/linux-zDY19G/linux-4.8.15/arch/x86/mm/dump_pagetables.c:225
>>>> note_page+0x5e8/0x790 [   13.588388] x86/mm: Found insecure W+X mapping
>>>> at address ffff880000000000/0xffff880000000000 ...
>>>> [   13.608867] x86/mm: Checked W+X mappings: FAILED, 4602 W+X pages
>>>> found.
>>> Now this is a know issue, but I'm pretty convinced one that's entirely
>>> unrelated to your problem.
>> I thought we fixed this. That's what is_hypervisor_range() was
>> introduced for, and I haven't seen this warning since then.
> When? Which commit?
> Maybe it isn't (yet) in the Debian tree and/or I am using a kernel which 
> doesn't contain that fix.


Commit f4e342c87776884f0309942a3880ca7e835239f9.

All it did was to prevent the walker from trying to verify pages in the
hypervisor range so it doesn't really fix anything. It's just that I am
surprised to see this warning again.


-boris

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