Re: [PATCH] kvm, x86: Properly check whether a pfn is an MMIO or not

From: Raslan, KarimAllah
Date: Thu Sep 15 2016 - 01:55:06 EST



> On Jun 22, 2016, at 3:41 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
>
>
> On 22/06/2016 04:34, KarimAllah Ahmed wrote:
>> pfn_valid check is not sufficient because it only checks if a page has a struct
>> page or not, if for example "mem=" was passed to the kernel some valid pages
>> won't have a struct page. This means that if guests were assigned valid memory
>> that lies after the mem= boundary it will be passed uncached to the guest no
>> matter what the guest caching attributes are for this memory.
>
> How can you pass memory after the mem= boundary to the guest?

Does my previous reply answer your question?

>
> Paolo
>

Amazon Development Center Germany GmbH
Berlin - Dresden - Aachen
main office: Krausenstr. 38, 10117 Berlin
Geschaeftsfuehrer: Dr. Ralf Herbrich, Christian Schlaeger
Ust-ID: DE289237879
Eingetragen am Amtsgericht Charlottenburg HRB 149173 B