Re: [PATCH v2 02/18] x86/sgx: Store struct sgx_encl when allocating new VA pages

[Kristen Carlson Accardi]

On Fri, 2022-12-02 at 13:35 -0800, Dave Hansen wrote:
> On 12/2/22 10:36, Kristen Carlson Accardi wrote:
> > When allocating new Version Array (VA) pages, pass the struct
> > sgx_encl
> > of the enclave that is allocating the page. sgx_alloc_epc_page()
> > will
> > store this value in the encl_owner field of the struct
> > sgx_epc_page. In
> > a later patch, VA pages will be placed in an unreclaimable queue,
> > and then when the cgroup max limit is reached and there are no more
> > reclaimable pages and the enclave must be oom killed, all the
> > VA pages associated with that enclave can be uncharged and freed.
> 
> What does this have to do with the 'encl' that is being passed,
> though?
> 
> In other words, why is this new sgx_epc_page-to-encl mapping needed
> for
> VA pages now, but it wasn't before?

When we OOM kill an enclave, we want to get rid of all the associated
VA pages too. Prior to this patch, there wasn't a way to easily get the
VA pages associated with an enclave.