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Message-ID: <f031ac1bd6b16509f1d714cd65e6b017f054940c.camel@linux.intel.com>
Subject: Re: [RFC PATCH 03/20] x86/sgx: Track owning enclave in VA EPC pages
From:   Kristen Carlson Accardi <kristen@linux.intel.com>
To:     Dave Hansen <dave.hansen@intel.com>, linux-kernel@vger.kernel.org,
        linux-sgx@vger.kernel.org, cgroups@vger.kernel.org,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Cc:     Sean Christopherson <seanjc@google.com>
Date:   Thu, 22 Sep 2022 13:04:06 -0700
In-Reply-To: <1adb03c8-1274-3898-0677-03015a1f5a5d@intel.com>
References: <20220922171057.1236139-1-kristen@linux.intel.com>
         <20220922171057.1236139-4-kristen@linux.intel.com>
         <1adb03c8-1274-3898-0677-03015a1f5a5d@intel.com>
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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;
...