linux-kernel - Re: [PATCH v15 15/23] x86/sgx: Add wrappers for ENCLS leaf functions

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Date:   Sat, 3 Nov 2018 15:17:35 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-sgx@...r.kernel.org, Dave Hansen <dave.hansen@...el.com>,
        sean.j.christopherson@...el.com, nhorman@...hat.com,
        npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, haitao.huang@...el.com,
        mark.shanahan@...el.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, suresh.b.siddha@...el.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v15 15/23] x86/sgx: Add wrappers for ENCLS leaf functions

On Sat, Nov 3, 2018 at 1:18 AM Jarkko Sakkinen
<jarkko.sakkinen@...ux.intel.com> wrote:
>
> ENCLS is an umbrella instruction for a variety of cpl0 SGX functions.
> The ENCLS function that is executed is specified in EAX, with each
> function potentially having more leaf-specific operands beyond EAX.
> ENCLS introduces its own (positive value) error codes that (some)
> leafs use to return failure information in EAX.  Leafs that return
> an error code also modify RFLAGS.  And finally, ENCLS generates
> ENCLS-specific non-fatal #GPs and #PFs, i.e. a bug-free kernel may
> encounter faults on ENCLS that must be handled gracefully.
>
> Because of the complexity involved in encoding ENCLS and handling its
> assortment of failure paths, executing any given leaf is not a simple
> matter of emitting ENCLS.
>
> To enable adding support for ENCLS leafs with minimal fuss, add a
> two-layer macro system along with an encoding scheme to allow wrappers
> to return trap numbers along ENCLS-specific error codes.  The bottom
> layer of the macro system splits between the leafs that return an
> error code and those that do not.  The second layer generates the
> correct input/output annotations based on the number of operands for
> each leaf function.

> +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */

> +/**

I dunno if kernel-doc script still complains about this.

> + * Copyright(c) 2016-18 Intel Corporation.
> + */

-- 
With Best Regards,
Andy Shevchenko