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

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Date:   Fri, 2 Apr 2021 20:31:19 +0200
From:   Jethro Beekman <jethro@...tanix.com>
To:     Dave Hansen <dave.hansen@...el.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 2021-04-02 17:53, Dave Hansen wrote:
> On 4/2/21 1:38 AM, Jethro Beekman wrote:
>>> So, we're talking here about pages that have been EEADDED, but for
>>> which we do not want to include the entire contents of the page?
>>> Do these contents always include the beginning of the page, or can
>>> the holes be anywhere?
>> Holes can be anywhere, and EEXTEND calls need not be sequential in
>> memory address or even relate to the most recently EADDed page.
> 
> I think you're referring to the SGX architecture itself here.  The
> architecture permits this, right?

Yes.

> But, why would an enclave loader application ever do this? 

e.g. to save space

> Is this something we want to support in Linux?

Why not? Is there a good reason to not fully support this part of the CPU architecture?

--
Jethro Beekman | Fortanix


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