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    SubjectRe: [PATCH 10/54] KVM: x86/mmu: Replace EPT shadow page shenanigans with simpler check
    On Wed, Jun 23, 2021, Paolo Bonzini wrote:
    > On 23/06/21 18:17, Sean Christopherson wrote:
    > > > What the commit message doesn't say is, did we miss this
    > > > opportunity all along, or has there been a change since commit
    > > > 47c42e6b4192 ("KVM: x86: fix handling of role.cr4_pae and rename it
    > > > to 'gpte_size'", 2019-03-28) that allows this?
    > >
    > > The code was wrong from the initial "unsync" commit. The 4-byte vs.
    > > 8-byte check papered over the real bug, which was that the roles were
    > > not checked for compabitility. I suspect that the bug only
    > > manisfested as an observable problem when the GPTE sizes mismatched,
    > > thus the PAE check was added.
    >
    > I meant that we really never needed is_ept_sp, and you could have used the
    > simpler check already at the time you introduced gpte_is_8_bytes. But anyway
    > I think we're in agreement.

    Ah, yes, I was too clever :-/

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