On Mon, Jun 29, 2020 at 08:27:19AM -0700, Sean Christopherson wrote:

Hmm, I was going to say that SGX_ENCL_INITIALIZED can't be checked until
encl->lock is held, but that's not true for this path as mutual exclusion
is provided by the SGX_ENCL_IOCTL flag.  So yeah, this can be checked at
the same time as SGX_ENCL_CREATED in sgx_ioc_enclave_init().

Right, so my point is to have state checks for flags which make sense in
all ioctl entry points, in order to catch a misuse early. But we're on
the same page.

ENCLS[EINIT] is interruptible because it has such a high latency, e.g. 50k+
cycles on success.  If an IRQ/NMI/SMI becomes pending, EINIT may fail with
SGX_UNMASKED_EVENT so that the event can be serviced.

The idea behind the double loop is to try EINIT in a tight loop, then back
off and sleep for a while before retrying that tight inner loop.

That gist of that kinda wants to be in a comment over that double-loop for
future on-lookers.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette