Re: [PATCH v7 00/39] KVM: x86: hyper-v: Fine-grained TLB flush + L2 TLB flush features

[Paolo Bonzini]

On 6/13/22 15:38, Vitaly Kuznetsov wrote:
> Changes since v6:
> - Rebase to the latest kvm/queue [8baacf67c76c], newly introduced
>    selftests had to be adapted to the overhauled API [blame Sean].
> - Rename 'entry' to 'flush_all_entry' in hv_tlb_flush_enqueue() [Max].
> - Add "KVM: selftests: Rename 'evmcs_test' to 'hyperv_evmcs'" patch.
> - Collect R-b tags.
>
> Original description:
>
> Currently, KVM handles HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST{,EX} requests
> by flushing the whole VPID and this is sub-optimal. This series introduces
> the required mechanism to make handling of these requests more
> fine-grained by flushing individual GVAs only (when requested). On this
> foundation, "Direct Virtual Flush" Hyper-V feature is implemented. The
> feature allows L0 to handle Hyper-V TLB flush hypercalls directly at
> L0 without the need to reflect the exit to L1. This has at least two
> benefits: reflecting vmexit and the consequent vmenter are avoided + L0
> has precise information whether the target vCPU is actually running (and
> thus requires a kick).

I haven't reviewed the selftests part yet, but for the rest I only had 
two very small comments.

Paolo