From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
"Huang, Kai" <kai.huang@intel.com>,
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
Date: Fri, 11 Jan 2019 15:19:56 -0800 [thread overview]
Message-ID: <20190111231956.GB29769@linux.intel.com> (raw)
In-Reply-To: <20190111125826.GA5400@linux.intel.com>
On Fri, Jan 11, 2019 at 02:58:26PM +0200, Jarkko Sakkinen wrote:
> On Wed, Jan 09, 2019 at 08:31:37AM -0800, Sean Christopherson wrote:
> > On Tue, Jan 08, 2019 at 02:54:11PM -0800, Andy Lutomirski wrote:
> > > On Tue, Jan 8, 2019 at 2:09 PM Sean Christopherson
> > > <sean.j.christopherson@intel.com> wrote:
> > > >
> > > > Cleaner in the sense that it's faster to get basic support up and running
> > > > since there are fewer touchpoints, but there are long term ramifications
> > > > to cramming EPC management in KVM.
> > > >
> > > > And at this point I'm not stating any absolutes, e.g. how EPC will be
> > > > handled by KVM. What I'm pushing for is to not eliminate the possibility
> > > > of having the SGX subsystem own all EPC management, e.g. don't tie
> > > > /dev/sgx to a single enclave.
> > >
> > > I haven't gone and re-read all the relevant SDM bits, so I'll just
> > > ask: what, if anything, are the actual semantics of mapping "raw EPC"
> > > like this? You can't actually do anything with the mapping from user
> > > mode unless you actually get an enclave created and initialized in it
> > > and have it mapped at the correct linear address, right? I still
> > > think you have the right idea, but it is a bit unusual.
> >
> > Correct, the EPC is inaccessible until a range is "mapped" with ECREATE.
> > But I'd argue that it's not unusual, just different. And really it's not
> > all that different than userspace mmap'ing /dev/sgx/enclave prior to
> > ioctl(ENCLAVE_CREATE). In that case, userspace can still (attempt to)
> > access the "raw" EPC, i.e. generate a #PF, the kernel/driver just happens
> > to consider any faulting EPC address without an associated enclave as
> > illegal, e.g. signals SIGBUS.
> >
> > The /dev/sgx/epc case simply has different semantics for moving pages in
> > and out of the EPC, i.e. different fault and eviction semantics. Yes,
> > this allows the guest kernel to directly access the "raw" EPC, but that's
> > conceptually in line with hardware where priveleged software can directly
> > "access" the EPC (or rather, the abort page for all intents and purposes).
> > I.e. it's an argument for requiring certain privileges to open /dev/sgx/epc,
> > but IMO it's not unusual.
> >
> > Maybe /dev/sgx/epc is a poor name and is causing confusion, e.g.
> > /dev/sgx/virtualmachine might be more appropriate.
>
> What do you mean by saying "requiring certain privileges"? Are you
> saying that "raw EPC" (lets say /dev/vmsgx, which probably the name I
> will use for the device *if* it is required) device would require
> differet privileged than /dev/sgx?
I don't think it would be mandatory, especially if PROVISION and EINITTOKEN
attributes are routed through securityfs, but it might be nice to have
since the functionality provided by /dev/vmsgx would be different than
/dev/sgx.
Side topic, what's the reasoning for doing /dev/sgx and /dev/vmsgx instead
of /dev/sgx/{enclave,vm,etc...}?
next prev parent reply other threads:[~2019-01-11 23:19 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 21:57 [RFC PATCH v5 0/5] x86: Add vDSO exception fixup for SGX Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 1/5] x86/vdso: Add support for exception fixup in vDSO functions Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 2/5] x86/fault: Add helper function to sanitize error code Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 3/5] x86/fault: Attempt to fixup unhandled #PF on ENCLU before signaling Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 4/5] x86/traps: Attempt to fixup exceptions in vDSO " Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 5/5] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions Sean Christopherson
2018-12-19 9:21 ` Jarkko Sakkinen
2018-12-18 4:18 ` [RFC PATCH v5 0/5] x86: Add vDSO exception fixup for SGX Jarkko Sakkinen
2018-12-18 15:08 ` Sean Christopherson
2018-12-19 4:43 ` Jarkko Sakkinen
2018-12-19 5:03 ` Jarkko Sakkinen
2018-12-19 7:58 ` x86/sgx: uapi change proposal Jarkko Sakkinen
2018-12-19 8:41 ` Jethro Beekman
2018-12-19 9:11 ` Jarkko Sakkinen
2018-12-19 9:36 ` Jethro Beekman
2018-12-19 10:43 ` Jarkko Sakkinen
2018-12-19 14:45 ` Sean Christopherson
2018-12-20 2:58 ` Andy Lutomirski
2018-12-20 10:32 ` Jarkko Sakkinen
2018-12-20 13:12 ` Jarkko Sakkinen
2018-12-20 13:19 ` Jarkko Sakkinen
2018-12-22 8:16 ` Jarkko Sakkinen
[not found] ` <20181222082502.GA13275@linux.intel.com>
2018-12-23 12:52 ` Jarkko Sakkinen
2018-12-23 20:42 ` Andy Lutomirski
2018-12-24 11:52 ` Jarkko Sakkinen
2019-01-02 20:47 ` Sean Christopherson
2019-01-03 15:02 ` Jarkko Sakkinen
[not found] ` <20190103162634.GA8610@linux.intel.com>
2019-01-09 14:45 ` Jarkko Sakkinen
2018-12-21 16:28 ` Sean Christopherson
2018-12-21 17:12 ` Andy Lutomirski
2018-12-21 18:24 ` Sean Christopherson
2018-12-21 23:41 ` Jarkko Sakkinen
2018-12-23 20:41 ` Andy Lutomirski
2018-12-24 12:01 ` Jarkko Sakkinen
2018-12-21 23:37 ` Jarkko Sakkinen
2018-12-22 6:32 ` Jarkko Sakkinen
2019-01-08 19:27 ` Huang, Kai
2019-01-08 22:09 ` Sean Christopherson
2019-01-08 22:54 ` Andy Lutomirski
2019-01-09 16:31 ` Sean Christopherson
2019-01-10 21:34 ` Andy Lutomirski
2019-01-10 22:22 ` Huang, Kai
2019-01-10 23:54 ` Sean Christopherson
2019-01-11 0:30 ` Andy Lutomirski
2019-01-11 1:32 ` Sean Christopherson
2019-01-11 12:58 ` Jarkko Sakkinen
2019-01-11 13:00 ` Jarkko Sakkinen
2019-01-11 23:19 ` Sean Christopherson [this message]
2019-01-18 14:37 ` Jarkko Sakkinen
2019-01-10 17:45 ` Jarkko Sakkinen
2019-01-10 21:36 ` Andy Lutomirski
2019-01-11 16:07 ` Jarkko Sakkinen
2019-01-09 5:24 ` Huang, Kai
2019-01-09 17:16 ` Sean Christopherson
2019-01-10 0:21 ` Huang, Kai
2019-01-10 0:40 ` Sean Christopherson
2019-01-10 17:43 ` Jarkko Sakkinen
2018-12-20 10:30 ` Jarkko Sakkinen
2018-12-19 14:43 ` Dr. Greg
2018-12-20 10:34 ` Jarkko Sakkinen
2018-12-20 22:06 ` Dr. Greg
2018-12-21 13:48 ` Jarkko Sakkinen
2018-12-20 12:08 ` Arnd Bergmann
2018-12-20 12:49 ` Jarkko Sakkinen
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