[Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[octane indice]

Hello

I'm using qemu a lot for testing.

I have to test some scenarios involving intel-VT machines.

Can qemu emulates the intel-VT (or AMD pacifica) behavior on any type of
machine?

Is it possible? Is it planned?

Thank you

Eurolines : Voyagez au meilleur prix : http://www.alinto.com/pub/

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Alexander Graf]

Hi,

On Jan 20, 2008, at 7:29 PM, octane indice wrote:

> Hello
>
> I'm using qemu a lot for testing.
>
> I have to test some scenarios involving intel-VT machines.
>
> Can qemu emulates the intel-VT (or AMD pacifica) behavior on any  
> type of
> machine?

SVM (AMD pacifica) is party integrated. You don't have an IOMMU and  
high SVM exit codes don't work (mostly unused anyway), but apart from  
that it should be mostly feature-identical to what you get from a real  
K9 CPU.

You are welcome to implement VMX as well ;-).

Regards,

Alex

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Alexey Eremenko]

Note however, that as far as I know, all the Qemu accelerators - KQemu
and KVM do not support this.

-- 
-Alexey Eremenko "Technologov"

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Dor Laor]

Alexey, you're wrong again.


svm is supported.

On Sun, 2008-01-20 at 20:59 +0200, Alexey Eremenko wrote:
> Note however, that as far as I know, all the Qemu accelerators - KQemu
> and KVM do not support this.
> 

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Alexander Graf]

He was talking about running SVM code in KQemu/KVM. It might work with  
kqemu (I honestly have not tested it, but see no reason it shouldn't),  
but definitely not with KVM. Simply said, you can not run KVM inside  
of a KVM virtualized machine.

Regards,

Alex

On Jan 20, 2008, at 8:21 PM, Dor Laor wrote:

> Alexey, you're wrong again.
>
>
> svm is supported.
>
> On Sun, 2008-01-20 at 20:59 +0200, Alexey Eremenko wrote:
>> Note however, that as far as I know, all the Qemu accelerators -  
>> KQemu
>> and KVM do not support this.
>>
>
>
>

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[andrzej zaborowski]

On 20/01/2008, Alexander Graf <alex@csgraf.de> wrote:
> He was talking about running SVM code in KQemu/KVM. It might work with
> kqemu (I honestly have not tested it, but see no reason it shouldn't),
> but definitely not with KVM. Simply said, you can not run KVM inside
> of a KVM virtualized machine.

What would be the problem with supporting that in KVM? The host SVM
should just report that the guest is trying to execute an SVM insn and
generate an Illegal Operation which would be handled by qemu.

Regards

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Izik Eidus]

andrzej zaborowski wrote:
> On 20/01/2008, Alexander Graf <alex@csgraf.de> wrote:
>   
>> He was talking about running SVM code in KQemu/KVM. It might work with
>> kqemu (I honestly have not tested it, but see no reason it shouldn't),
>> but definitely not with KVM. Simply said, you can not run KVM inside
>> of a KVM virtualized machine.
>>     
>
> What would be the problem with supporting that in KVM? The host SVM
> should just report that the guest is trying to execute an SVM insn and
> generate an Illegal Operation which would be handled by qemu.
>
> Regards
>
>
>   
right now kvm never call to qemu for cpu emulation, qemu is used just 
for the devices,
if kvm have something that it need to emulate it have a small emulator 
inside the kernel,

(ofcruse with modification what you just said is possible)

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Alexander Graf]

On Jan 20, 2008, at 8:52 PM, andrzej zaborowski wrote:

> On 20/01/2008, Alexander Graf <alex@csgraf.de> wrote:
>> He was talking about running SVM code in KQemu/KVM. It might work  
>> with
>> kqemu (I honestly have not tested it, but see no reason it  
>> shouldn't),
>> but definitely not with KVM. Simply said, you can not run KVM inside
>> of a KVM virtualized machine.
>
> What would be the problem with supporting that in KVM? The host SVM
> should just report that the guest is trying to execute an SVM insn and
> generate an Illegal Operation which would be handled by qemu.
>
> Regards
>
>

Yes, you're completely right about this. The main reason it isn't  
implemented in kvm is that nobody did it yet. It is actually one of  
the things on my "would like to do"-list, so if things stay the way  
they are, maybe you will see this feature in kvm someday.

Regards,

Alex

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[octane indice]

En réponse à Alexander Graf <alex@csgraf.de> :
> >> He was talking about running SVM code in KQemu/KVM. It
> >>might work with kqemu 

No, I have a intel PIII CPU without vt extensions.

I want to test KVM.

My idea is to use a qemu machine emulating the VT instruction.

So, in the qemu machine, I could load KVM.

But it doesn't seem to work.

I downloaded a qemu-0.9.1, compiled it.

A cat /proc/cpuinfo inside qemu doesn't show me vmx nor svm.

Am I forgotting something?

Thanks

Eurolines : Voyagez au meilleur prix : http://www.alinto.com/pub/

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Alexey Eremenko]

Try: qemu-system-x86_64

By default, you use "qemu" which is a 32-bit emulator. I think SVM is
available only to 64-bit guests. The 64-bit emulator is named:
"qemu-system-x86_64", and don't worry, your CPU will work, despite
being 32-bit without SVM. 64-bit part is for guests, not for host.

I'm not sure if your guest OS also needs to be 64-bit, but it better be.

-- 
-Alexey Eremenko "Technologov"

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[octane indice]

En réponse à Alexander Graf <alex@csgraf.de> :
> He was talking about running SVM code in KQemu/KVM. It might
> work with  
> kqemu (I honestly have not tested it, but see no reason it
> shouldn't),  
> but definitely not with KVM. Simply said, you can not run KVM
> inside  
> of a KVM virtualized machine.
>
I just want to run KVM in a non VT machine. And I want to test
a lot of things. So if qemu can emulate it, it's really good for me.
I need to test hvm-Xen too.

So, as qemu emulates CPU, does it emulates [pacifica|VT] 
extensions too?
With a patch?

Do you have a link to some docs?

thanks

Eurolines : Voyagez au meilleur prix : http://www.alinto.com/pub/

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Alexey Eremenko]

> So, as qemu emulates CPU, does it emulates [pacifica|VT]
> extensions too?
> With a patch?

Yes, Qemu 0.91, can emulate AMD Pacifica/SVM, according to:
http://fabrice.bellard.free.fr/qemu/changelog.html

So yes, theoretically KVM should work inside Qemu, but don't expect
real-hardware performance.

-- 
-Alexey Eremenko "Technologov"

Re: [Qemu-devel] emulate the Intel-VT behavior on any type of CPU

[Dor Laor]

Opps, me wrong this time, it should have been private.
Didn't notice the reply address is different. Sorry.

On Sun, 2008-01-20 at 21:21 +0200, Dor Laor wrote:
> Alexey, you're wrong again.
> 
> 
> svm is supported.
> 
> On Sun, 2008-01-20 at 20:59 +0200, Alexey Eremenko wrote:
> > Note however, that as far as I know, all the Qemu accelerators - KQemu
> > and KVM do not support this.
> > 
> 
> 
>