Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
From:   Andy Lutomirski <luto@amacapital.net>
Mime-Version: 1.0 (1.0)
Subject: Re: [PATCH v36 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call
Date:   Mon, 10 Aug 2020 17:52:09 -0700
Message-Id: <DD7996A6-CBA3-47CE-8DF2-9A6ADD3FE89E@amacapital.net>
References: <20200810234837.GH14724@linux.intel.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Nathaniel McCallum <npmccallum@redhat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        X86 ML <x86@kernel.org>, linux-sgx@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Jethro Beekman <jethro@fortanix.com>,
        Cedric Xing <cedric.xing@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        asapek@google.com, Borislav Petkov <bp@alien8.de>,
        chenalexchen@google.com, Conrad Parker <conradparker@google.com>,
        cyhanish@google.com, Dave Hansen <dave.hansen@intel.com>,
        "Huang, Haitao" <haitao.huang@intel.com>,
        Josh Triplett <josh@joshtriplett.org>,
        "Huang, Kai" <kai.huang@intel.com>,
        "Svahn, Kai" <kai.svahn@intel.com>, Keith Moyer <kmoy@google.com>,
        Christian Ludloff <ludloff@google.com>,
        Neil Horman <nhorman@redhat.com>,
        Patrick Uiterwijk <puiterwijk@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Thomas Gleixner <tglx@linutronix.de>, yaozhangx@google.com
In-Reply-To: <20200810234837.GH14724@linux.intel.com>
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Aug 10, 2020, at 4:48 PM, Sean Christopherson <sean.j.christopherson@in=
tel.com> wrote:
>=20
> =EF=BB=BFOn Mon, Aug 10, 2020 at 04:08:46PM -0700, Andy Lutomirski wrote:
>> What am I missing?  I still don't really understand why we are
>> supporting this mechanism at all.  Just the asm code to invoke the
>> callback seems to be about half of the entire function.
>=20
> Because the Intel SDK (and other SDKs?) wants to use the host stack to pas=
s
> parameters out of the enclave.

Ugh, right.  I forgot about that particular abomination.

I suppose that passing a context pointer would be reasonable.=