[libvirt] [PATCH 2/5] Introduce SMM feature

[Michal Privoznik]

On 01.08.2016 21:10, Laszlo Ersek wrote:
> On 08/01/16 19:05, Gerd Hoffmann wrote:
>>   Hi,
>>
>>> If it does, then the host kernel should be 4.4 or later. (If we want to
>>> capture version numbers, then for each minor release, the latest patch
>>> level should be required: 4.4.16, 4.5.7, 4.6.5, 4.7.0, because there
>>> have been a number of KVM tweaks and stable backports for SMM support.)
>>
>> Better check /dev/kvm for the KVM_CAP_X86_SMM capability, otherwise the
>> rhel-7 kernel is out even though smm is backported.
>>
>> Probably libvirt already has checks for other caps so it should be easy.
> 
> The problem is that KVM_CAP_X86_SMM does not guarantee that all the
> tricky bugfixes are present in the host kernel.
> 
>

Moreover, libvirt does not validate nor check guest kernel. And the only
/dev/kvm/ caps we check are:

KVM_CAP_IOMMU - to see if legacy PCI passthrough works

KVM_CAP_PPC_SMT -
KVM_CAP_MAX_VCPUS -
KVM_CAP_NR_VCPUS  - for some vCPUs counts

I don't think libvirt should check for KVM_CAP_x86_SMM. I mean, if we go
down the rabbit hole, libvirt would have to check everything. The buck
has to stop somewhere.

Michal