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.
On Tue, May 22, 2018 at 7:16 AM, Liran Alon <liran.alon@xxxxxxxxxx> wrote:
> Hi,
>
> This series aims to optimize KVM nested-VPID implementation.
> Note: All the patches in this series are indepdendent and can be
> applied seperately.
>
> 1st patch is just a small refactoring change.
>
> 2nd patch fixes a corner-case of not failing INVVPID type 0
> (individiual-address) in case operand.vpid==0.
>
> 3rd patch fixes an ancient issue of unnecessarely flushing TLB when
> exiting from L2 to L1 even though TLB entries populated by L2 are
> tagged with different VPID (vmx->nested.vpid02) than TLB entries
> populated by L1 (vmx->vpid).
>
> 4rd patch optimizes L1 INVVPID type 0 (individiual-address) handling
> by emulating it with INVVPID type 0 executed at L0 level. This allows
> flushing only a single TLB entry tagged with vmx->nested.vpid02
> instead of all TLB entries tagged with vmx->nested.vpid02.
>
> Regards,
> -Liran Alon
