linux-kernel - Re: [PATCH v11 09/13] x86, sgx: basic routines for enclave page cache

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Date:   Mon, 25 Jun 2018 12:21:55 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>,
        x86@...nel.org, platform-driver-x86@...r.kernel.org
Cc:     dave.hansen@...el.com, nhorman@...hat.com, npmccallum@...hat.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>,
        "open list:INTEL SGX" <intel-sgx-kernel-dev@...ts.01.org>
Subject: Re: [PATCH v11 09/13] x86, sgx: basic routines for enclave page
 cache

On Wed, 2018-06-20 at 08:26 -0700, Sean Christopherson wrote:
> >  bool sgx_enabled __ro_after_init = false;
> >  EXPORT_SYMBOL(sgx_enabled);
> > +bool sgx_lc_enabled __ro_after_init;
> > +EXPORT_SYMBOL(sgx_lc_enabled);
> > +atomic_t sgx_nr_free_pages = ATOMIC_INIT(0);
> > +EXPORT_SYMBOL(sgx_nr_free_pages);
> > +struct sgx_epc_bank sgx_epc_banks[SGX_MAX_EPC_BANKS];
> > +EXPORT_SYMBOL(sgx_epc_banks);
> > +int sgx_nr_epc_banks;
> > +EXPORT_SYMBOL(sgx_nr_epc_banks);
> > +LIST_HEAD(sgx_active_page_list);
> > +EXPORT_SYMBOL(sgx_active_page_list);
> > +DEFINE_SPINLOCK(sgx_active_page_list_lock);
> > +EXPORT_SYMBOL(sgx_active_page_list_lock);
> 
> I don't think we should be exporting anything other than sgx_enabled
> and sgx_lc_enabled.  The only external use of a symbol that can't be
> trivially (re)moved is in the driver's sgx_pm_suspend() in sgx_main.c,
> which uses the sgx_active_page_list to invalidate enclaves.  And that
> behavior seems unsafe, e.g. an enclave could theoretically have zero
> pages on the active list and so could be missed in the suspend flow.

Fully agreed. Just forgotten cruft...

/Jarkko