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Date:   Wed, 5 Jun 2019 17:29:08 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Jethro Beekman <jethro@fortanix.com>,
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Subject: Re: [PATCH v20 15/28] x86/sgx: Add the Linux SGX Enclave Driver
Message-ID: <20190605142908.GD11331@linux.intel.com>
References: <20190417103938.7762-1-jarkko.sakkinen@linux.intel.com>
 <20190417103938.7762-16-jarkko.sakkinen@linux.intel.com>
 <20190422215831.GL1236@linux.intel.com>
 <6dd981a7-0e38-1273-45c1-b2c0d8bf6fed@fortanix.com>
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 <20190604201232.GA7775@linux.intel.com>
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On Tue, Jun 04, 2019 at 01:12:32PM -0700, Sean Christopherson wrote:
> On Tue, Apr 23, 2019 at 05:26:53PM -0700, Sean Christopherson wrote:
> > On Tue, Apr 23, 2019 at 11:29:24PM +0000, Jethro Beekman wrote:
> > > On 2019-04-22 14:58, Sean Christopherson wrote:
> > > >Where do we stand on removing the ACPI and platform_driver dependencies?
> > > >Can we get rid of them sooner rather than later?
> > > 
> > > You know my position on this...
> > > https://www.spinics.net/lists/linux-sgx/msg00624.html . I don't really have
> > > any new arguments.
> > > 
> > > Considering the amount of planned changes for the driver post-merge, I think
> > > it's crucial that the driver part can be swapped out with alternative
> > > implementations.
> > 
> > This gets far outside of my area of expertise as I think this is more of
> > a policy question as opposed to a technical question, e.g. do we export
> > function simply to allow out-of-tree alternatives.
> > 
> > > >Now that the core SGX code is approaching stability, I'd like to start
> > > >sending RFCs for the EPC virtualization and KVM bits to hash out that side
> > > >of things.  The ACPI crud is the last chunk of code that would require
> > > >non-trivial changes to the core SGX code for the proposed virtualization
> > > >implementation.  I'd strongly prefer to get it out of the way before
> > > >sending the KVM RFCs.
> > > 
> > > What kind of changes? Wouldn't KVM just be another consumer of the same API
> > > used by the driver?
> > 
> > Nope, userspace "only" needs to be able to mmap() arbitrary chunks of EPC.
> > Except for EPC management, which is already in built into the kernel, the
> > EPC virtualization code has effectively zero overlap with the driver.  Of
> > course this is all technically speculative since none of this is upstream...
> 
> Jarkko, can you weigh in with your thoughts on the ACPI stuff?

If there is LKM, then it is required (for loading the LKM).

I think we should see how the access control gets implemented first and
see what constraints it introduces. It might help with to make the right
decision whether to allow LKM or not.

/Jarkko