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    SubjectRe: [PATCH v19 058/130] KVM: x86/mmu: Add a private pointer to struct kvm_mmu_page
    Date
    On Fri, 2024-03-15 at 10:23 +1300, Huang, Kai wrote:
    > We have 3 page tables as you mentioned:
    >
    > PT: page table
    > - Shared PT is visible to KVM and it is used by CPU.
    > - Private PT is used by CPU but it is invisible to KVM.
    > - Dummy PT is visible to KVM but not used by CPU.  It is used to
    >    propagate PT change to the actual private PT which is used by CPU.
    >
    > If I recall correctly, we used to call the last one "mirrored
    > (private)
    > page table".
    >
    > I lost the tracking when we changed to use "dummy page table", but it
    > seems to me "mirrored" is better than "dummy" because the latter
    > means
    > it is useless but in fact it is used to propagate changes to the real
    > private page table used by hardware.

    Mirrored makes sense to me. So like:

    Private - Table actually mapping private alias, in TDX module
    Shared - Shared alias table, visible in KVM
    Mirror - Mirroring private, visible in KVM

    >
    > Btw, one nit, perhaps:
    >
    > "Shared PT is visible to KVM and it is used by CPU." -> "Shared PT is
    > visible to KVM and it is used by CPU for shared mappings".
    >
    > To make it more clearer it is used for "shared mappings".
    >
    > But this may be unnecessary to others, so up to you.

    Yep, this seems clearer.
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