linux-kernel - Re: [PATCH v3 00/34] KVM: x86: hyper-v: Fine-grained TLB flush + L2 TLB flush feature

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Message-ID: <87bkwe3bk0.fsf@redhat.com>
Date:   Tue, 03 May 2022 17:01:19 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 00/34] KVM: x86: hyper-v: Fine-grained TLB flush + L2
 TLB flush feature

Vitaly Kuznetsov <vkuznets@...hat.com> writes:

> Changes since v1:

This should've beed 'since v2', obviously.

...

>
> 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).

FWIW, patches still apply cleanly to kvm/queue so probably there's no
need to resend.

-- 
Vitaly