To be clear: HyperThreading is relevant but not a panacea here. Disabling HT helps for the hypervisor leak, and while the Intel microcode changes now incorporate HyperThreading status into key generation, we don't know if that prevents the SGX leak. Ensuring untrusted code is on a sibling core and L1 flushes should be a mitigation for the SMM attack (it's identical to the VMM attack in that sense).