Re: [PATCH v2 12/16] KVM: x86: Make Hyper-V emulation optional

[Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>]

On 06/12/2023 13:36, Vitaly Kuznetsov wrote:
> Jeremi Piotrowski <jpiotrowski@linux.microsoft.com> writes:
> 
>> On Tue, Dec 05, 2023 at 11:36:26AM +0100, Vitaly Kuznetsov wrote:
>>> Hyper-V emulation in KVM is a fairly big chunk and in some cases it may be
>>> desirable to not compile it in to reduce module sizes as well as the attack
>>> surface. Introduce CONFIG_KVM_HYPERV option to make it possible.
>>>
>>> Note, there's room for further nVMX/nSVM code optimizations when
>>> !CONFIG_KVM_HYPERV, this will be done in follow-up patches.
>>>
>>> Reorganize Makefile a bit so all CONFIG_HYPERV and CONFIG_KVM_HYPERV files
>>> are grouped together.
>>>
>>
>> Wanted to test this for the case where KVM is running as a nested hypervisor on
>> Hyper-V but it doesn't apply cleanly - what base did you use? Tried v6.6,
>> v6.7-rc1, and v6.7-rc4.
> 
> Hi Jeremi,
> 
> the base was 'kvm/next' (git://git.kernel.org/pub/scm/virt/kvm/kvm.git,
> 'next' branch):
> 
> commit e9e60c82fe391d04db55a91c733df4a017c28b2f (kvm/next)
> Author: Paolo Bonzini <pbonzini@redhat.com>
> Date:   Tue Nov 21 11:24:08 2023 -0500
> 
>     selftests/kvm: fix compilation on non-x86_64 platforms
> 

Hi Vitaly,

Thanks. Just tested this running in an AMD Hyper-V guest with CONFIG_KVM_HYPERV
unset, and tested nested virtualization - no regressions. You can have my tag:

Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>

Jeremi