Hello, all
An interesting (at least to me) thinking came up to me when I found
that the lguest was removed. But I don't have enough knowledge
to find out the answer nor energy to implement it in some time.
Is it possible to implement kvm-pv which allows kvm to run on
the boxes without hardware virtualization support, so that
qemu/kvm can be used on clouds such as aws, azure?
Without hardware virtualization support, the host kvm-pv module and
the guest linux kernel need to cooperate in some ways. And some kvm
facilities can help. For instance, the existing shadow-paging, which
was not introduced when lguest had been added to kernel, could be
reused to help on mmu virtualization. For guest kernel/userspace
separation in x86_64, the intel cpu's segment registers can help too.
(or use a new set of page-table for the guest kernel on amd64).
The thought is quite shallow, but I hope this email brings some
inspirations rather than annoyance. And I'm sorry if the later things
would happen.
Thanks,
Lai.
On Thu, Aug 17, 2017 at 1:31 AM, Juergen Gross <[email protected]> wrote:
> Lguest seems to be rather unused these days. It has seen only patches
> ensuring it still builds the last two years and its official state is
> "Odd Fixes".
>
> Nuke it in order to be able to clean up the paravirt code.
On 29/09/2017 17:47, Lai Jiangshan wrote:
> Hello, all
>
> An interesting (at least to me) thinking came up to me when I found
> that the lguest was removed. But I don't have enough knowledge
> to find out the answer nor energy to implement it in some time.
>
> Is it possible to implement kvm-pv which allows kvm to run on
> the boxes without hardware virtualization support, so that
> qemu/kvm can be used on clouds such as aws, azure?
No, please don't. :) Even Xen is moving from PV to PVH (paravirtualized
hardware with event channels, grant tables and the like, but still using
hardware extensions for MMU).
Rather, cloud providers should help getting nested virtualization ready
for production use. At least for KVM it's not that far.
Paolo
> Without hardware virtualization support, the host kvm-pv module and
> the guest linux kernel need to cooperate in some ways. And some kvm
> facilities can help. For instance, the existing shadow-paging, which
> was not introduced when lguest had been added to kernel, could be
> reused to help on mmu virtualization. For guest kernel/userspace
> separation in x86_64, the intel cpu's segment registers can help too.
> (or use a new set of page-table for the guest kernel on amd64).
>
> The thought is quite shallow, but I hope this email brings some
> inspirations rather than annoyance. And I'm sorry if the later things
> would happen.
>
> Thanks,
> Lai.
>
> On Thu, Aug 17, 2017 at 1:31 AM, Juergen Gross <[email protected]> wrote:
>> Lguest seems to be rather unused these days. It has seen only patches
>> ensuring it still builds the last two years and its official state is
>> "Odd Fixes".
>>
>> Nuke it in order to be able to clean up the paravirt code.
>
On Sat, Sep 30, 2017 at 12:39 AM, Paolo Bonzini <[email protected]> wrote:
> On 29/09/2017 17:47, Lai Jiangshan wrote:
>> Hello, all
>>
>> An interesting (at least to me) thinking came up to me when I found
>> that the lguest was removed. But I don't have enough knowledge
>> to find out the answer nor energy to implement it in some time.
>>
>> Is it possible to implement kvm-pv which allows kvm to run on
>> the boxes without hardware virtualization support, so that
>> qemu/kvm can be used on clouds such as aws, azure?
>
> No, please don't. :) Even Xen is moving from PV to PVH (paravirtualized
> hardware with event channels, grant tables and the like, but still using
> hardware extensions for MMU).
>
> Rather, cloud providers should help getting nested virtualization ready
> for production use. At least for KVM it's not that far.
>
Although I'm not business man, I don't think the top cloud provider[s]
would allow nested virtualization, however mature nested virtualization
is. Even xen-pv is unable to be nested in the aws and azure.
Thanks,
Lai
>
----- Lai Jiangshan <[email protected]> ha scritto:
> On Sat, Sep 30, 2017 at 12:39 AM, Paolo Bonzini <[email protected]> wrote:
> > On 29/09/2017 17:47, Lai Jiangshan wrote:
> >> Hello, all
> >>
> >> An interesting (at least to me) thinking came up to me when I found
> >> that the lguest was removed. But I don't have enough knowledge
> >> to find out the answer nor energy to implement it in some time.
> >>
> >> Is it possible to implement kvm-pv which allows kvm to run on
> >> the boxes without hardware virtualization support, so that
> >> qemu/kvm can be used on clouds such as aws, azure?
> >
> > No, please don't. :) Even Xen is moving from PV to PVH (paravirtualized
> > hardware with event channels, grant tables and the like, but still using
> > hardware extensions for MMU).
> >
> > Rather, cloud providers should help getting nested virtualization ready
> > for production use. At least for KVM it's not that far.
> >
>
> Although I'm not business man, I don't think the top cloud provider[s]
> would allow nested virtualization, however mature nested virtualization
> is. Even xen-pv is unable to be nested in the aws and azure.
Check the contributors to KVM nested virtualization, you might be surprised.
Nested Xen PV is not possible because the Xen hypervisor cannot run as a PV guest. It's a technical limitation.
Paolo
>
> Thanks,
> Lai
>
> >