On Mon, Aug 31, 2020 at 11:19:19AM +0300, Paraschiv, Andra-Irina wrote: > > > On 19/08/2020 14:26, Greg KH wrote: > > > > On Wed, Aug 19, 2020 at 01:15:59PM +0200, Alexander Graf wrote: > > > > > > On 17.08.20 15:09, Andra Paraschiv wrote: > > > > Nitro Enclaves (NE) is a new Amazon Elastic Compute Cloud (EC2) capability > > > > that allows customers to carve out isolated compute environments within EC2 > > > > instances [1]. > > > > > > > > For example, an application that processes sensitive data and runs in a VM, > > > > can be separated from other applications running in the same VM. This > > > > application then runs in a separate VM than the primary VM, namely an enclave. > > > > > > > > An enclave runs alongside the VM that spawned it. This setup matches low latency > > > > applications needs. The resources that are allocated for the enclave, such as > > > > memory and CPUs, are carved out of the primary VM. Each enclave is mapped to a > > > > process running in the primary VM, that communicates with the NE driver via an > > > > ioctl interface. > > > > > > > > In this sense, there are two components: > > > > > > > > 1. An enclave abstraction process - a user space process running in the primary > > > > VM guest that uses the provided ioctl interface of the NE driver to spawn an > > > > enclave VM (that's 2 below). > > > > > > > > There is a NE emulated PCI device exposed to the primary VM. The driver for this > > > > new PCI device is included in the NE driver. > > > > > > > > The ioctl logic is mapped to PCI device commands e.g. the NE_START_ENCLAVE ioctl > > > > maps to an enclave start PCI command. The PCI device commands are then > > > > translated into actions taken on the hypervisor side; that's the Nitro > > > > hypervisor running on the host where the primary VM is running. The Nitro > > > > hypervisor is based on core KVM technology. > > > > > > > > 2. The enclave itself - a VM running on the same host as the primary VM that > > > > spawned it. Memory and CPUs are carved out of the primary VM and are dedicated > > > > for the enclave VM. An enclave does not have persistent storage attached. > > > > > > > > The memory regions carved out of the primary VM and given to an enclave need to > > > > be aligned 2 MiB / 1 GiB physically contiguous memory regions (or multiple of > > > > this size e.g. 8 MiB). The memory can be allocated e.g. by using hugetlbfs from > > > > user space [2][3]. The memory size for an enclave needs to be at least 64 MiB. > > > > The enclave memory and CPUs need to be from the same NUMA node. > > > > > > > > An enclave runs on dedicated cores. CPU 0 and its CPU siblings need to remain > > > > available for the primary VM. A CPU pool has to be set for NE purposes by an > > > > user with admin capability. See the cpu list section from the kernel > > > > documentation [4] for how a CPU pool format looks. > > > > > > > > An enclave communicates with the primary VM via a local communication channel, > > > > using virtio-vsock [5]. The primary VM has virtio-pci vsock emulated device, > > > > while the enclave VM has a virtio-mmio vsock emulated device. The vsock device > > > > uses eventfd for signaling. The enclave VM sees the usual interfaces - local > > > > APIC and IOAPIC - to get interrupts from virtio-vsock device. The virtio-mmio > > > > device is placed in memory below the typical 4 GiB. > > > > > > > > The application that runs in the enclave needs to be packaged in an enclave > > > > image together with the OS ( e.g. kernel, ramdisk, init ) that will run in the > > > > enclave VM. The enclave VM has its own kernel and follows the standard Linux > > > > boot protocol. > > > > > > > > The kernel bzImage, the kernel command line, the ramdisk(s) are part of the > > > > Enclave Image Format (EIF); plus an EIF header including metadata such as magic > > > > number, eif version, image size and CRC. > > > > > > > > Hash values are computed for the entire enclave image (EIF), the kernel and > > > > ramdisk(s). That's used, for example, to check that the enclave image that is > > > > loaded in the enclave VM is the one that was intended to be run. > > > > > > > > These crypto measurements are included in a signed attestation document > > > > generated by the Nitro Hypervisor and further used to prove the identity of the > > > > enclave; KMS is an example of service that NE is integrated with and that checks > > > > the attestation doc. > > > > > > > > The enclave image (EIF) is loaded in the enclave memory at offset 8 MiB. The > > > > init process in the enclave connects to the vsock CID of the primary VM and a > > > > predefined port - 9000 - to send a heartbeat value - 0xb7. This mechanism is > > > > used to check in the primary VM that the enclave has booted. > > > > > > > > If the enclave VM crashes or gracefully exits, an interrupt event is received by > > > > the NE driver. This event is sent further to the user space enclave process > > > > running in the primary VM via a poll notification mechanism. Then the user space > > > > enclave process can exit. > > > > > > > > Thank you. > > > > > > > This version reads very well, thanks a lot Andra! > > > > > > Greg, would you mind to have another look over it? > > Will do, it's in my to-review queue, behind lots of other patches... > > > > I have a set of updates that can be included in a new revision, v8 e.g. new > NE custom error codes for invalid flags / enclave CID, "shutdown" function > for the NE PCI device driver, a couple more checks wrt invalid flags and > enclave vsock CID, documentation and sample updates. There is also the > option to have these updates as follow-up patches. > > Greg, let me know what would work fine for you with regard to the review of > the patch series. A new series is always fine with me... thanks, greg k-h
