kvm vmx shadow paging question

kvm vmx shadow paging question

[Mika Penttilä]

Hi,

While studying the vmx code, and the shadow page tables usage (no ept involved),
I wondered the GUEST_CR3 usage. If no ept, GUEST_CR3 points to the shadow tables.
But the format of sptes is always 64 bit. How is that with 32 bit hosts, is the GUEST_CR3
similar to EPT format, 4 level 64 bit always or how is this working on 32 bit?

Thanks,
Mika

Re: kvm vmx shadow paging question

[Mika Penttilä]

On 13.08.2016 17:38, Mika Penttilä wrote:

> Hi,
>
> While studying the vmx code, and the shadow page tables usage (no ept involved),
> I wondered the GUEST_CR3 usage. If no ept, GUEST_CR3 points to the shadow tables.
> But the format of sptes is always 64 bit. How is that with 32 bit hosts, is the GUEST_CR3
> similar to EPT format, 4 level 64 bit always or how is this working on 32 bit?
>
> Thanks,
> Mika
>
Hmm seems non PAE 32 bit host without ept enabled is not supported combination, right ?

--Mika

Re: kvm vmx shadow paging question

[Mika Penttilä]

On 13.08.2016 18:47, Mika Penttilä wrote:

> On 13.08.2016 17:38, Mika Penttilä wrote:
>
>> Hi,
>>
>> While studying the vmx code, and the shadow page tables usage (no ept involved),
>> I wondered the GUEST_CR3 usage. If no ept, GUEST_CR3 points to the shadow tables.
>> But the format of sptes is always 64 bit. How is that with 32 bit hosts, is the GUEST_CR3
>> similar to EPT format, 4 level 64 bit always or how is this working on 32 bit?
>>
>> Thanks,
>> Mika
>>
> Hmm seems non PAE 32 bit host without ept enabled is not supported combination, right ?
>
> --Mika
>
>

Ping, am I correct that for using shadow mmu with x86 kvm host you need at least 32bit PAE enabled host
(because shadow ptes are always 64 bit, in PAE or long format)?

--Mika