From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kristen Carlson Accardi <kristen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Subject: Re: [RFC PATCH 03/20] x86/sgx: Track owning enclave in VA EPC pages
Date: Thu, 22 Sep 2022 13:04:06 -0700
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To: Dave Hansen <dave.hansen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-sgx-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jarkko Sakkinen <jarkko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Dave Hansen <dave.hansen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
Cc: Sean Christopherson <seanjc-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

On Thu, 2022-09-22 at 11:55 -0700, Dave Hansen wrote:
> On 9/22/22 10:10, Kristen Carlson Accardi wrote:
> > -struct sgx_epc_page *sgx_alloc_va_page(bool reclaim)
> > +struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool
> > reclaim)
> > =C2=A0{
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct sgx_epc_page *ep=
c_page;
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0int ret;
> > @@ -1218,6 +1219,8 @@ struct sgx_epc_page *sgx_alloc_va_page(bool
> > reclaim)
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0return ERR_PTR(-EFAULT);
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0}
> > =C2=A0
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0epc_page->owner =3D encl;
> > +
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0return epc_page;
> > =C2=A0}
>=20
> BTW, is there a flag or any other way to tell to what kind of object
> ->owner points?

The owner will only be an sgx_encl type if it is a va page, so to tell
what kind of object owner is, you look at the epc page flags - like
this:
        if (epc_page->flags & SGX_EPC_PAGE_ENCLAVE)
                encl =3D ((struct sgx_encl_page *)epc_page->owner)->encl;
        else if (epc_page->flags & SGX_EPC_PAGE_VERSION_ARRAY)
                encl =3D epc_page->owner;
...