linux-kernel - Re: [PATCH RESEND 0/3] x86/sgx: eextend ioctl

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Date:   Thu, 8 Apr 2021 08:54:34 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Jethro Beekman <jethro@...tanix.com>,
        Raoul Strackx <raoul.strackx@...tanix.com>,
        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>,
        linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND 0/3] x86/sgx: eextend ioctl


On 4/8/21 8:27 AM, Jethro Beekman wrote:
> But the native “executable format” for SGX is very clearly defined in
> the Intel SDM as a specific sequence of ECREATE, EADD, EEXTEND and
> EINIT calls. It's that sequence that's used for loading the enclave
> and it's that sequence that's used for code signing. So when I say
> save space I mean save space in the native format.
> 
> Not EEXTENDing unnecessarily also reduces enclave load time if
> you're looking for additional arguments.
I look forward to all of this being clearly explained in your resubmission.

> SGX defines lots of things and you may not see the use case for all
> of this immediately. No one has a usecase for creating enclaves with
> SECS.SSAFRAMESIZE = 1000 or TCS.NSSA = 3. Why did you not demand
> checks for this in the ECREATE/EADD ioctls?
There's a difference between adding code to support a feature and adding
code to *RESTRICT* use of a feature.