On 24/05/2018 19:04, Liran Alon wrote:
>
> ----- liran.alon@xxxxxxxxxx wrote:
>
>> ----- sean.j.christopherson@xxxxxxxxx wrote:
>>
>>> On Tue, 2018-05-22 at 08:50 -0700, Jim Mattson wrote:
>>>> While we're on the subject, is there any need for L0 to allocate
>> a
>>>> vpid02 in the common case, where nested EPT is enabled?
>>>>
>>>> Per section 28.3.2 of the SDM, volume 3, when EPT is enabled,
>>> combined
>>>> mappings in the TLB are tagged by {VPID, PCID, EP4TA}. With
>> nested
>>>> EPT, vmcs02 and vmcs01 do not share an EP4TA. Therefore, I think
>> it
>>>> suffices to simply copy the VPID field from vmcs12 to vmcs02 in
>>> this
>>>> case.
>>>
>>> VPID handling in general looks like it could use a good once-over,
>>> e.g. vpid02 allocation can be delayed until prepare_vmcs02_full(),
>>> we never re-attempt VPID allocation in the (extremely unlikely)
>>> case that there are no available VPIDs at vmx_create_vcpu(), and
>>> load_vmcs12_host_state() explicitly flushes the TLB when VPID is
>>> enabled because it has obsolete code that assumes L1 and L2 always
>>> share a VPID.
>>
>> Agree with all the above.
>> As a starting point, I think we should apply this current series as it
>> at-least
>> handle the load_vmcs12_host_state() issue. :)
>>
>> Will also add handling for the rest of these issues in my upcoming
>> series.
>> Thanks for explicitly pointing these out.
>>
>>>
>
> Paolo / Radim:
> Do you agree with me that it makes sense to first apply this series as a first step?
> Or do you want me to resend these patches as part of a bigger series that will fix the extra issues we discussed here?
>
Yes, I agree enitrely.
Paolo
