Re: [PATCH v17 18/23] platform/x86: Intel SGX driver

[Jarkko Sakkinen]

On Mon, Dec 17, 2018 at 02:20:48PM -0800, Sean Christopherson wrote:
> The only potential hiccup I can see is the build flow.  Currently,
> EADD+EEXTEND is done via a work queue to avoid major performance issues
> (10x regression) when userspace is building multiple enclaves in parallel
> using goroutines to wrap Cgo (the issue might apply to any M:N scheduler,
> but I've only confirmed the Golang case).  The issue is that allocating
> an EPC page acts like a blocking syscall when the EPC is under pressure,
> i.e. an EPC page isn't immediately available.  This causes Go's scheduler
> to thrash and tank performance[1].

I don't see any major issues having that kthread. All the code that
maps the enclave would be removed.

I would only allow to map enclave to process address space after the
enclave has been initialized i.e. SGX_IOC_ENCLAVE_ATTACH.

/Jarkko