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Date:   Fri, 29 Jul 2022 19:25:45 +0530
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Subject: Re: [PATCHv2 5/7] KVM: SVM: Add VNMI support in inject_nmi
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To:     Sean Christopherson <seanjc@google.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Maxim Levitsky <mlevitsk@redhat.com>,
        Tom Lendacky <thomas.lendacky@amd.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20220709134230.2397-1-santosh.shukla@amd.com>
 <20220709134230.2397-6-santosh.shukla@amd.com> <Yth2eik6usFvC4vW@google.com>
 <23b43ea0-0a92-e132-ada3-ebe86dbaf673@amd.com> <YuPmRbBcUp931KMP@google.com>
From:   "Shukla, Santosh" <santosh.shukla@amd.com>
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On 7/29/2022 7:23 PM, Sean Christopherson wrote:
> On Fri, Jul 29, 2022, Shukla, Santosh wrote:
>> Hi Sean,
>>
>> On 7/21/2022 3:11 AM, Sean Christopherson wrote:
>>> On Sat, Jul 09, 2022, Santosh Shukla wrote:
>>>> +	++vcpu->stat.nmi_injections;
>>>> +	if (is_vnmi_enabled(svm)) {
>>>> +		vmcb = get_vnmi_vmcb(svm);
>>>> +		WARN_ON(vmcb->control.int_ctl & V_NMI_PENDING);
>>>
>>> Haven't read the spec, but based on the changelog I assume the flag doesn't get
>>> cleared until the NMI is fully delivered.  That means this WARN will fire if a
>>> VM-Exit occurs during delivery as KVM will re-inject the event, e.g. if KVM is
>>> using shadow paging and a #PF handle by KVM occurs during delivery.
>>>
>>
>> Right,.
>>
>>
>> For the above scenario i.e.. if VMEXIT happens during delivery of virtual NMI
>> then EXITINTINFO will be set accordingly and V_NMI_MASK is saved as 0.
>> hypervisor will re-inject event in next VMRUN.
>>
>> I just wanted to track above scenario,. I will replace it with pr_debug().
> 
> No, this is normal (albeit uncommon) behavior, don't print anything.  Even if it

Ok.

Thanks,
Santosh

> weren't normal behavior, pr_debug() is usually the wrong choice in KVM.