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    SubjectRe: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST
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    On 23.11.21 10:06, Paolo Bonzini wrote:
    > On 11/19/21 16:39, David Hildenbrand wrote:
    >>> If qmeu can put all the guest memory in a memfd and not map it, then
    >>> I'd also like to see that the IOMMU can use this interface too so we
    >>> can have VFIO working in this configuration.
    >>
    >> In QEMU we usually want to (and must) be able to access guest memory
    >> from user space, with the current design we wouldn't even be able to
    >> temporarily mmap it -- which makes sense for encrypted memory only. The
    >> corner case really is encrypted memory. So I don't think we'll see a
    >> broad use of this feature outside of encrypted VMs in QEMU. I might be
    >> wrong, most probably I am:)
    >
    > It's not _that_ crazy an idea, but it's going to be some work to teach
    > KVM that it has to kmap/kunmap around all memory accesses.

    I'm also concerned about userspace access. But you sound like you have a
    plan :)

    --
    Thanks,

    David / dhildenb

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