linux-kernel - Re: [PATCH v2 07/11] KVM: x86: add a delayed hardware NMI injection interface

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Message-ID: <93051e27-ae2f-826c-d2fb-03d3144d092e@amd.com>
Date:   Wed, 8 Feb 2023 15:05:46 +0530
From:   Santosh Shukla <santosh.shukla@....com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Cc:     kvm@...r.kernel.org, Sandipan Das <sandipan.das@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        Jiaxi Chen <jiaxi.chen@...ux.intel.com>,
        Babu Moger <babu.moger@....com>, linux-kernel@...r.kernel.org,
        Jing Liu <jing2.liu@...el.com>,
        Wyes Karny <wyes.karny@....com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 07/11] KVM: x86: add a delayed hardware NMI injection
 interface

On 2/1/2023 2:42 AM, Sean Christopherson wrote:
> On Sat, Jan 28, 2023, Sean Christopherson wrote:
>> On Tue, Nov 29, 2022, Maxim Levitsky wrote:
>>> @@ -10015,13 +10022,34 @@ static void process_nmi(struct kvm_vcpu *vcpu)
>>>  	 * Otherwise, allow two (and we'll inject the first one immediately).
>>>  	 */
>>>  	if (static_call(kvm_x86_get_nmi_mask)(vcpu) || vcpu->arch.nmi_injected)
>>> -		limit = 1;
>>> +		limit--;
>>> +
>>> +	/* Also if there is already a NMI hardware queued to be injected,
>>> +	 * decrease the limit again
>>> +	 */
>>
>> 	/*
>> 	 * Block comment ...
>> 	 */
>>
>>> +	if (static_call(kvm_x86_get_hw_nmi_pending)(vcpu))
>>
>> I'd prefer "is_hw_nmi_pending()" over "get", even if it means not pairing with
>> "set".  Though I think that's a good thing since they aren't perfect pairs.
> 
> Thinking more, I vote for s/hw_nmi/vnmi.  "hardware" usually means actual hardware,
> i.e. a pending NMI for the host.

Ah!,. better. 

Thanks,
Santosh