linux-kernel - Re: [PATCH RFC 04/15] KVM: Implement ring-based dirty memory tracking

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Message-ID: <20191217164244.GE7258@xz-x1>
Date:   Tue, 17 Dec 2019 11:42:44 -0500
From:   Peter Xu <peterx@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Christophe de Dinechin <dinechin@...hat.com>,
        Christophe de Dinechin <christophe.de.dinechin@...il.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [PATCH RFC 04/15] KVM: Implement ring-based dirty memory tracking

On Tue, Dec 17, 2019 at 05:31:48PM +0100, Paolo Bonzini wrote:
> On 17/12/19 16:38, Peter Xu wrote:
> > There's still time to persuade me to going back to it. :)
> > 
> > (Though, yes I still like current solution... if we can get rid of the
> >  only kvmgt ugliness, we can even throw away the per-vm ring with its
> >  "extra" 4k page.  Then I suppose it'll be even harder to persuade me :)
> 
> Actually that's what convinced me in the first place, so let's
> absolutely get rid of both the per-VM ring and the union.  Kevin and
> Alex have answered and everybody seems to agree.

Yeah that'd be perfect.

However I just noticed something... Note that we still didn't read
into non-x86 archs, I think it's the same question as when I asked
whether we can unify the kvm[_vcpu]_write() interfaces and you'd like
me to read the non-x86 archs - I think it's time I read them, because
it's still possible that non-x86 archs will still need the per-vm
ring... then that could be another problem if we want to at last
spread the dirty ring idea outside of x86.

-- 
Peter Xu