1# Intel SGX 2 3Intel® Software Guard Extensions (Intel® SGX) is an Intel technology designed 4to increase the security of application code and data. Cloud-Hypervisor supports 5SGX virtualization through KVM. Because SGX is built on hardware features that 6cannot be emulated in software, virtualizing SGX requires support in KVM and in 7the host kernel. The required Linux and KVM changes can be found in the 8[KVM SGX Tree](https://github.com/intel/kvm-sgx). 9 10Utilizing SGX in the guest requires a kernel/OS with SGX support, e.g. a kernel 11built using the [SGX Linux Development Tree](https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-sgx.git) 12or the [KVM SGX Tree](https://github.com/intel/kvm-sgx). Running KVM SGX as the 13guest kernel allows nested virtualization of SGX. 14 15For more information about SGX, please refer to the [SGX Homepage](https://software.intel.com/sgx). 16 17For more information about SGX SDK and how to test SGX, please refer to the 18following [instructions](https://github.com/intel/linux-sgx). 19 20## Cloud-Hypervisor support 21 22Assuming the host exposes `/dev/sgx_vepc`, we can pass SGX enclaves through 23the guest. 24 25In order to use SGX enclaves within a Cloud-Hypervisor VM, we must define one 26or several Enclave Page Cache (EPC) sections. Here is an example of a VM being 27created with 2 EPC sections, the first one being 64MiB with pre-allocated 28memory, the second one being 32MiB with no pre-allocated memory. 29 30```bash 31./cloud-hypervisor \ 32 --cpus boot=1 \ 33 --memory size=1G \ 34 --disk path=focal-server-cloudimg-amd64.raw \ 35 --kernel vmlinux \ 36 --cmdline "console=ttyS0 console=hvc0 root=/dev/vda1 rw" \ 37 --sgx-epc id=epc0,size=64M,prefault=on id=epc1,size=32M,prefault=off 38``` 39 40Once booted, and assuming your guest kernel contains the patches from the 41[KVM SGX Tree](https://github.com/intel/kvm-sgx), you can validate SGX devices 42have been correctly created under `/dev/sgx`: 43 44```bash 45ls /dev/sgx* 46/dev/sgx_enclave /dev/sgx_provision /dev/sgx_vepc 47``` 48 49From this point, it is possible to run any SGX application from the guest, as 50it will access `/dev/sgx_enclave` device to create dedicated SGX enclaves. 51 52Note: There is only one contiguous SGX EPC region, which contains all SGX EPC 53sections. This region is exposed through ACPI and marked as reserved through 54the e820 table. It is treated as yet another device, which means it should 55appear at the end of the guest address space. 56