linux-kernel - Re: [PATCH v2 09/15] KVM: Move memslot deletion to helper function

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Message-ID: <20191023092919.GF2652@e113682-lin.lund.arm.com>
Date:   Wed, 23 Oct 2019 11:29:19 +0200
From:   Christoffer Dall <christoffer.dall@....com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     James Hogan <jhogan@...nel.org>,
        Paul Mackerras <paulus@...abs.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Wanpeng Li <wanpengli@...cent.com>, kvm@...r.kernel.org,
        David Hildenbrand <david@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Cornelia Huck <cohuck@...hat.com>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm-ppc@...r.kernel.org,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        kvmarm@...ts.cs.columbia.edu, Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v2 09/15] KVM: Move memslot deletion to helper function

Hi Sean,

On Mon, Oct 21, 2019 at 05:35:31PM -0700, Sean Christopherson wrote:
> Move memslot deletion into its own routine so that the success path for
> other memslot updates does not need to use kvm_free_memslot(), i.e. can
> explicitly destroy the dirty bitmap when necessary.  This paves the way
> for dropping @dont from kvm_free_memslot(), i.e. all callers now pass
> NULL for @dont.
> 
> Add a comment above the code to make a copy of the existing memslot
> prior to deletion, it is not at all obvious that the pointer will become
> stale due sorting and/or installation of new memslots.

nit: due to / during

> 
> Note, kvm_arch_commit_memory_region() allows an architecture to free
> resources when moving a memslot or changing its flags, i.e. implement
> logic similar to the dirty bitmap is handling, if such functionality is

nit: s/is handling/handling/

> needed in the future.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>

Otherwise looks good to me.

Acked-by: Christoffer Dall <christoffer.dall@....com>