linux-kernel - Re: [PATCH] KVM: x86: Initialize tdp

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Message-ID: <20200528022730.GE25962@linux.intel.com>
Date:   Wed, 27 May 2020 19:27:31 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        syzbot+904752567107eefb728c@...kaller.appspotmail.com
Subject: Re: [PATCH] KVM: x86: Initialize tdp_level during vCPU creation

On Wed, May 27, 2020 at 06:56:02PM +0200, Paolo Bonzini wrote:
> On 27/05/20 18:23, Sean Christopherson wrote:
> > Hmm, one option would be to make .get_tdp_level() pure function by passing
> > in vcpu->arch.maxphyaddr.  That should make the comment redundant.  I don't
> > love bleeding VMX's implementation into the prototype, but that ship has
> > kinda already sailed.
> 
> Well, it's not bleeding the implementation that much, guest MAXPHYADDR
> is pretty much the only reason why it's a function and not a constant.
> 
> Another possibility BTW is to make the callback get_max_tdp_level and
> make get_tdp_level a function in mmu.c.

I like that idea.  We could even avoid get_max_tdp_level() by passing that
info into kvm_configure_mmu(), though that may not actually be cleaner.
I'll play around with it.