linux-kernel - Re: [PATCH v2 06/11] KVM: SVM: add wrappers to enable/disable IRET interception

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Date:   Mon, 13 Feb 2023 20:20:48 +0530
From:   Santosh Shukla <santosh.shukla@....com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Cc:     Santosh Shukla <santosh.shukla@....com>, 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 06/11] KVM: SVM: add wrappers to enable/disable IRET
 interception

On 2/1/2023 2:37 AM, Sean Christopherson wrote:
> On Thu, Dec 08, 2022, Maxim Levitsky wrote:
>> On Thu, 2022-12-08 at 17:39 +0530, Santosh Shukla wrote:
>>>
>>> On 12/6/2022 5:44 PM, Maxim Levitsky wrote:
>>>>>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>>>>>> index 512b2aa21137e2..cfed6ab29c839a 100644
>>>>>> --- a/arch/x86/kvm/svm/svm.c
>>>>>> +++ b/arch/x86/kvm/svm/svm.c
>>>>>> @@ -2468,16 +2468,29 @@ static int task_switch_interception(struct kvm_vcpu *vcpu)
>>>>>>  			       has_error_code, error_code);
>>>>>>  }
>>>>>>  
>>>>>> +static void svm_disable_iret_interception(struct vcpu_svm *svm)
>>>>>> +{
>>>>>> +	if (!sev_es_guest(svm->vcpu.kvm))
>>>>>> +		svm_clr_intercept(svm, INTERCEPT_IRET);
>>>>>> +}
>>>>>> +
>>>>>> +static void svm_enable_iret_interception(struct vcpu_svm *svm)
>>>>>> +{
>>>>>> +	if (!sev_es_guest(svm->vcpu.kvm))
>>>>>> +		svm_set_intercept(svm, INTERCEPT_IRET);
>>>>>> +}
>>>>>> +
>>>>>
>>>>> nits:
>>>>> s/_iret_interception / _iret_intercept
>>>>> does that make sense?
>>>>
>>>> Makes sense.
> 
> I would rather go with svm_{clr,set}_iret_intercept().  I don't particularly like

ok.

> the SVM naming scheme, but I really dislike inconsistent naming.  If we want to
> clean up naming, I would love unify VMX and SVM nomenclature for things like this.
> 
>>>>  I can also move this to svm.h near the svm_set_intercept(), I think
>>>> it better a better place for this function there if no objections.
>>>>
>>> I think current approach is fine since function used in svm.c only. but I have
>>> no strong opinion on moving to svm.h either ways.
>>
>> I also think so, just noticed something in case there are any objections.
> 
> My vote is to keep it in svm.c unless we anticipate usage outside of svm.h.  Keeping

ok.

Thanks,
Santosh
> the implementation close to the usage makes it easer to understand what's going on,
> especially for something like this where there's a bit of "hidden" logic for SEV-ES.