On Thu, 2025-08-14 at 10:34 +0300, Reshetova, Elena wrote: > == Background == > > ENCLS[EUPDATESVN] is a new SGX instruction [1] which allows enclave > attestation to include information about updated microcode SVN without a > reboot. Before an EUPDATESVN operation can be successful, all SGX memory > (aka. EPC) must be marked as “unused” in the SGX hardware metadata > (aka.EPCM). This requirement ensures that no compromised enclave can > survive the EUPDATESVN procedure and provides an opportunity to generate > new cryptographic assets. > > == Solution == > > Attempt to execute ENCLS[EUPDATESVN] every time the first file descriptor > is obtained via sgx_(vepc_)open(). In the most common case the microcode > SVN is already up-to-date, and the operation succeeds without updating SVN. > > Note: while in such cases the underlying crypto assets are regenerated, it > does not affect enclaves' visible keys obtained via EGETKEY instruction. > > If it fails with any other error code than SGX_INSUFFICIENT_ENTROPY, this > is considered unexpected and the *open() returns an error. This should not > happen in practice. > > On contrary, SGX_INSUFFICIENT_ENTROPY might happen due to a pressure on the > system's DRNG (RDSEED) and therefore the *open() can be safely retried to > allow normal enclave operation. > > [1] Runtime Microcode Updates with Intel Software Guard Extensions, > https://cdrdv2.intel.com/v1/dl/getContent/648682 > > Reviewed-by: Jarkko Sakkinen <jar...@kernel.org> > Signed-off-by: Elena Reshetova <elena.reshet...@intel.com> >
Reviewed-by: Kai Huang <kai.hu...@intel.com>
