linux-kernel - Re: [RFC PATCH 03/20] x86/sgx: Track owning enclave in VA EPC pages

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Message-ID: <f031ac1bd6b16509f1d714cd65e6b017f054940c.camel@linux.intel.com>
Date:   Thu, 22 Sep 2022 13:04:06 -0700
From:   Kristen Carlson Accardi <kristen@...ux.intel.com>
To:     Dave Hansen <dave.hansen@...el.com>, linux-kernel@...r.kernel.org,
        linux-sgx@...r.kernel.org, cgroups@...r.kernel.org,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>
Cc:     Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH 03/20] x86/sgx: Track owning enclave in VA EPC pages

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)
> >  {
> >         struct sgx_epc_page *epc_page;
> >         int ret;
> > @@ -1218,6 +1219,8 @@ struct sgx_epc_page *sgx_alloc_va_page(bool
> > reclaim)
> >                 return ERR_PTR(-EFAULT);
> >         }
> >  
> > +       epc_page->owner = encl;
> > +
> >         return epc_page;
> >  }
> 
> 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 = ((struct sgx_encl_page *)epc_page->owner)->encl;
        else if (epc_page->flags & SGX_EPC_PAGE_VERSION_ARRAY)
                encl = epc_page->owner;
...