On Thu, Mar 11, 2021, Kai Huang wrote:

From: Jarkko Sakkinen <jarkko@kernel.org>

EREMOVE takes a page and removes any association between that page and
an enclave.  It must be run on a page before it can be added into
another enclave.  Currently, EREMOVE is run as part of pages being freed
into the SGX page allocator.  It is not expected to fail.

KVM does not track how guest pages are used, which means that SGX
virtualization use of EREMOVE might fail.

Break out the EREMOVE call from the SGX page allocator.  This will allow
the SGX virtualization code to use the allocator directly.  (SGX/KVM
will also introduce a more permissive EREMOVE helper).

Implement original sgx_free_epc_page() as sgx_encl_free_epc_page() to be
more specific that it is used to free EPC page assigned to one enclave.
Print an error message when EREMOVE fails to explicitly call out EPC
page is leaked, and requires machine reboot to get leaked pages back.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Co-developed-by: Kai Huang <redacted>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Kai Huang <redacted>
---
v2->v3:

 - Fixed bug during copy/paste which results in SECS page and va pages are not
   correctly freed in sgx_encl_release() (sorry for the mistake).
 - Added Jarkko's Acked-by.

That Acked-by should either be dropped or moved above Co-developed-by to make
checkpatch happy.

Reviewed-by: Sean Christopherson <seanjc@google.com>