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    SubjectRe: [PATCH 03/25] x86/sgx: Support VMA permissions exceeding enclave permissions
    On Wed, Dec 01, 2021 at 11:23:01AM -0800, Reinette Chatre wrote:
    > === Summary ===
    >
    > An SGX VMA can only be created if its permissions are the same or
    > weaker than the Enclave Page Cache Map (EPCM) permissions. After VMA
    > creation this rule continues to be enforced by the page fault handler.
    >
    > With SGX2 the EPCM permissions of a page can change after VMA
    > creation resulting in the VMA exceeding the EPCM permissions and the
    > page fault handler incorrectly blocking access.
    >
    > Enable the VMA's pages to remain accessible while ensuring that
    > the page table entries are installed to match the EPCM permissions
    > without exceeding the VMA perms issions.

    I don't understand what the short summary means in English, and the
    commit message is way too bloated to make any conclusions. It really
    needs a rewrite.

    These were the questions I could not find answer for:

    1. Why it would be by any means safe to remove a permission check?
    2. Why not re-issuing mmap()'s is unfeasible? I.e. close existing
    VMA's and mmap() new ones.

    /Jarkko

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