Re: [PATCH v1 00/15] Add support for Nitro Enclaves

[Paraschiv, Andra-Irina]

On 24/04/2020 06:04, Longpeng (Mike, Cloud Infrastructure Service 
Product Dept.) wrote:
> 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 ?

Hi,

Nope, not that I know of so far.

Thanks,
Andra

> > 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.




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.