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Date:   Fri, 30 Jul 2021 16:47:57 -0400
From:   Hamza Mahfooz <someguy@effective-light.com>
Subject: Re: [PATCH] KVM: const-ify all relevant uses of struct
 kvm_memory_slot
To:     Peter Xu <peterx@redhat.com>
Cc:     linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        kvm@vger.kernel.org
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References: <20210713023338.57108-1-someguy@effective-light.com>
        <YQReyaxp/rwypHbR@t490s>
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Hey Peter,

On Fri, Jul 30 2021 at 04:19:21 PM -0400, Peter Xu <peterx@redhat.com> 
wrote:
> This patch breaks kvm/queue with above issue.  Constify of 
> kvm_memory_slot
> pointer should have nothing to do with this so at least it should 
> need a
> separate patch.  At the meantime I also don't understand why memcpy() 
> here,
> which seems to be even slower..

To const-ify the slot member of struct slot_rmap_walk_iterator, we need 
to
initialize a new struct and then copy it over (otherwise we would need 
to relay
on casting again or the compiler will complain about it).