linux-kernel - Re: [PATCH v3] kvm: svm: Use the hardware provided GPA instead of page walk

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Message-ID: <fa4e517a-2f17-eb8f-3d9e-404b40601f35@redhat.com>
Date:   Thu, 15 Dec 2016 14:31:20 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     David Hildenbrand <david@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>, kvm@...r.kernel.org
Cc:     thomas.lendacky@....com, rkrcmar@...hat.com, joro@...tes.org,
        x86@...nel.org, linux-kernel@...r.kernel.org, mingo@...hat.com,
        hpa@...or.com, tglx@...utronix.de, bp@...e.de
Subject: Re: [PATCH v3] kvm: svm: Use the hardware provided GPA instead of
 page walk



On 15/12/2016 14:09, David Hildenbrand wrote:
>>>
>>> bool exception_gpa_valid(struct kvm_vcpu)
>>> {
>>>     // check if svm
>>>     // check if exit code is NPF
>>>     // check ctxt
>>> }
>>
>> No, this would be a layering violation.  The emulator ops don't know
>> about svm and exit codes (and in fact it's trivial to implement this
>> optimization for vmx, with a slightly different logic), so we need to
>> have gpa_available.
> 
> I was rather thinking about adding an vmx/svm independent callback,
> which would return false for vmx for now. I just saw the variable
> and was wondering if it is really necessary.

The variable would probably just move into struct {vmx,svm}_vcpu.  Maybe
you could access the VMX/SVM exitcode directly, but doing that worries
me a bit...

Paolo