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Date:   Sat, 22 Dec 2018 10:16:49 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Andy Lutomirski <luto@kernel.org>,
        Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Jethro Beekman <jethro@fortanix.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "x86@kernel.org" <x86@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Haitao Huang <haitao.huang@linux.intel.com>,
        "Dr . Greg Wettstein" <greg@enjellic.com>
Subject: Re: x86/sgx: uapi change proposal
Message-ID: <20181222081649.GB8895@linux.intel.com>
References: <20181214215729.4221-1-sean.j.christopherson@intel.com>
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 <20181219144515.GA30909@linux.intel.com>
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On Thu, Dec 20, 2018 at 12:32:04PM +0200, Jarkko Sakkinen wrote:
> On Wed, Dec 19, 2018 at 06:58:48PM -0800, Andy Lutomirski wrote:
> > Can one of you explain why SGX_ENCLAVE_CREATE is better than just
> > opening a new instance of /dev/sgx for each encalve?
> 
> I think that fits better to the SCM_RIGHTS scenario i.e. you could send
> the enclav to a process that does not have necessarily have rights to
> /dev/sgx. Gives more robust environment to configure SGX.

Sean, is this why you wanted enclave fd and anon inode and not just use
the address space of /dev/sgx? Just taking notes of all observations.
I'm not sure what your rationale was (maybe it was somewhere). This was
something I made up, and this one is wrong deduction. You can easily
get the same benefit with /dev/sgx associated fd representing the
enclave.

This all means that for v19 I'm going without enclave fd involved with
fd to /dev/sgx representing the enclave. No anon inodes will be
involved.

/Jarkko