On 2020/4/23 21:19, Paraschiv, Andra-Irina wrote: > > > On 22/04/2020 00:46, Paolo Bonzini wrote: >> On 21/04/20 20:41, Andra Paraschiv wrote: >>> An enclave communicates with the primary VM via a local communication channel, >>> using virtio-vsock [2]. An enclave does not have a disk or a network device >>> attached. >> Is it possible to have a sample of this in the samples/ directory? > > I can add in v2 a sample file including the basic flow of how to use the ioctl > interface to create / terminate an enclave. > > Then we can update / build on top it based on the ongoing discussions on the > patch series and the received feedback. > >> >> I am interested especially in: >> >> - the initial CPU state: CPL0 vs. CPL3, initial program counter, etc. >> >> - the communication channel; does the enclave see the usual local APIC >> and IOAPIC interfaces in order to get interrupts from virtio-vsock, and >> where is the virtio-vsock device (virtio-mmio I suppose) placed in memory? >> >> - what the enclave is allowed to do: can it change privilege levels, >> what happens if the enclave performs an access to nonexistent memory, etc. >> >> - whether there are special hypercall interfaces for the enclave > > An enclave is a VM, running on the same host as the primary VM, that launched > the enclave. They are siblings. > > Here we need to think of two components: > > 1. An enclave abstraction process - a process running in the primary VM guest, > that uses the provided ioctl interface of the Nitro Enclaves kernel driver to > spawn an enclave VM (that's 2 below). > > How does all gets to an enclave VM running on the host? > > There is a Nitro Enclaves emulated PCI device exposed to the primary VM. The > driver for this new PCI device is included in the current patch series. > Hi Paraschiv, The new PCI device is emulated in QEMU ? If so, is there any plan to send the QEMU code ? > The ioctl logic is mapped to PCI device commands e.g. the NE_ENCLAVE_START ioctl > maps to an enclave start PCI command or the KVM_SET_USER_MEMORY_REGION maps to > an add memory 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. > > 2. The enclave itself - a VM running on the same host as the primary VM that > spawned it. > > The enclave VM has no persistent storage or network interface attached, it uses > its own memory and CPUs + its virtio-vsock emulated device for communication > with the primary VM. > > The memory and CPUs are carved out of the primary VM, they are dedicated for the > enclave. The Nitro hypervisor running on the host ensures memory and CPU > isolation between the primary VM and the enclave VM. > > > These two components need to reflect the same state e.g. when the enclave > abstraction process (1) is terminated, the enclave VM (2) is terminated as well. > > With regard to the communication channel, the primary VM has its own emulated > virtio-vsock PCI device. The enclave VM has its own emulated virtio-vsock device > as well. This channel is used, for example, to fetch data in the enclave and > then process it. An application that sets up the vsock socket and connects or > listens, depending on the use case, is then developed to use this channel; this > happens on both ends - primary VM and enclave VM. > > Let me know if further clarifications are needed. > >> >>> The proposed solution is following the KVM model and uses the KVM API to be able >>> to create and set resources for enclaves. An additional ioctl command, besides >>> the ones provided by KVM, is used to start an enclave and setup the addressing >>> for the communication channel and an enclave unique id. >> Reusing some KVM ioctls is definitely a good idea, but I wouldn't really >> say it's the KVM API since the VCPU file descriptor is basically non >> functional (without KVM_RUN and mmap it's not really the KVM API). > > It uses part of the KVM API or a set of KVM ioctls to model the way a VM is > created / terminated. That's true, KVM_RUN and mmap-ing the vcpu fd are not > included. > > Thanks for the feedback regarding the reuse of KVM ioctls. > > Andra > > > > > Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar > Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in > Romania. Registration number J22/2621/2005. -- --- Regards, Longpeng(Mike)
