linux-kernel - Re: [PATCH 2/3] kvm: mmu: Separate generating and setting mmio ptes

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Date:   Wed, 5 Feb 2020 15:37:18 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Ben Gardon <bgardon@...gle.com>
Cc:     Peter Xu <peterx@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Peter Shier <pshier@...gle.com>,
        Oliver Upton <oupton@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 2/3] kvm: mmu: Separate generating and setting mmio ptes

On 05/02/20 14:37, Vitaly Kuznetsov wrote:
>> +static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn,
>> +			   unsigned int access)
>> +{
>> +	u64 mask = make_mmio_spte(vcpu, gfn, access);
>> +	unsigned int gen = get_mmio_spte_generation(mask);
>> +
>> +	access = mask & ACC_ALL;
>> +
>>  	trace_mark_mmio_spte(sptep, gfn, access, gen);
> 'access' and 'gen' are only being used for tracing, would it rather make
> sense to rename&move it to the newly introduced make_mmio_spte()? Or do
> we actually need tracing for both?

You would have the same issue with sptep.

> Also, I dislike re-purposing function parameters.

Yes, "trace_mark_mmio_spte(sptep, gfn, mask & ACC_ALL, gen);" is
slightly better.

Paolo