linux-kernel - Re: [PATCH 0/5] KVM: SVM: nSVM: Implement Enlightened MSR-Bitmap for Hyper-V-on-KVM and fix it for KVM-on-Hyper-V

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Date:   Tue, 01 Feb 2022 15:31:42 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] KVM: SVM: nSVM: Implement Enlightened MSR-Bitmap
 for Hyper-V-on-KVM and fix it for KVM-on-Hyper-V

Paolo Bonzini <pbonzini@...hat.com> writes:

> On 12/20/21 16:21, Vitaly Kuznetsov wrote:
>> Enlightened MSR-Bitmap feature implements a PV protocol for L0 and L1
>> hypervisors to collaborate and skip unneeded updates to MSR-Bitmap.
>> KVM implements the feature for KVM-on-Hyper-V but it seems there was
>> a flaw in the implementation and the feature may not be fully functional.
>> PATCHes 1-2 fix the problem. The rest of the series implements the same
>> feature for Hyper-V-on-KVM.
>> 
>> Vitaly Kuznetsov (5):
>>    KVM: SVM: Drop stale comment from
>>      svm_hv_vmcb_dirty_nested_enlightenments()
>>    KVM: SVM: hyper-v: Enable Enlightened MSR-Bitmap support for real
>>    KVM: nSVM: Track whether changes in L0 require MSR bitmap for L2 to be
>>      rebuilt
>>    KVM: x86: Make kvm_hv_hypercall_enabled() static inline
>>    KVM: nSVM: Implement Enlightened MSR-Bitmap feature
>> 
>>   arch/x86/kvm/hyperv.c           | 12 +--------
>>   arch/x86/kvm/hyperv.h           |  6 ++++-
>>   arch/x86/kvm/svm/nested.c       | 47 ++++++++++++++++++++++++++++-----
>>   arch/x86/kvm/svm/svm.c          |  3 ++-
>>   arch/x86/kvm/svm/svm.h          | 16 +++++++----
>>   arch/x86/kvm/svm/svm_onhyperv.h | 12 +++------
>>   6 files changed, 63 insertions(+), 33 deletions(-)
>> 
>
> Queued 3-5 now, but it would be nice to have some testcases.
>

Thanks, indeed, I'll try to draft something up, both for nVMX and nSVM.

-- 
Vitaly