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Date:   Tue, 4 Jun 2019 13:12:32 -0700
From:   Sean Christopherson <sean.j.christopherson@intel.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc:     Jethro Beekman <jethro@fortanix.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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Subject: Re: [PATCH v20 15/28] x86/sgx: Add the Linux SGX Enclave Driver
Message-ID: <20190604201232.GA7775@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>
 <20190424002653.GB14422@linux.intel.com>
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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?