Re: [PATCH v17 18/23] platform/x86: Intel SGX driver

From: Andy Lutomirski
Date: Mon Dec 17 2018 - 14:55:28 EST

On Mon, Dec 17, 2018 at 11:53 AM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> On 12/17/18 11:49 AM, Jarkko Sakkinen wrote:
> >> Yeah, the code is built to have one VMA and only one VMA per enclave.
> >> You need to go over the origin of this restriction and what enforces this.
> > It is before ECREATE but after that you can split it with mprotect().
> >
> > Lets take an example. I'm not sure how we would acquire mm efficiently
> > in sgx_encl_page_reclaim() otherwise than having it as a field in encl.
> You're effectively rebuilding reverse-mapping infrastructure here. It's
> a frequent thing for the core VM to need to go from 'struct page' back
> to the page tables mapping it. For that we go (logically)
> page->{anon_vma,mapping}->vma->vm_mm->pagetable.

This is a bit outside my expertise here, but doesn't
unmap_mapping_range() do exactly what SGX wants?