Re: [PATCH v29 00/20] Intel SGX foundations

[Jarkko Sakkinen]

On Sun, Apr 26, 2020 at 11:57:53AM -0500, Dr. Greg wrote:
> On Wed, Apr 22, 2020 at 12:52:56AM +0300, Jarkko Sakkinen wrote:
> 
> Good day, I hope the weekend is going well for everyone.
> 
> > Intel(R) SGX is a set of CPU instructions that can be used by applications
> > to set aside private regions of code and data. The code outside the enclave
> > is disallowed to access the memory inside the enclave by the CPU access
> > control.
> >
> > ... [ elided ] ..
> > 
> > The current implementation requires that the firmware sets
> > IA32_SGXLEPUBKEYHASH* MSRs as writable so that ultimately the kernel can
> > decide what enclaves it wants run. The implementation does not create
> > any bottlenecks to support read-only MSRs later on.
> 
> It seems highly unlikely that a driver implementation with any type of
> support for read-only launch control registers would ever get into the
> kernel.  All one needs to do is review the conversations that Matthew
> Garrett's lockdown patches engender to get a sense of that, ie:
> 
> https://lwn.net/Articles/818277/

We do not require read-only MSRs.

/Jarkko