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

Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2020-04-26T01:55:40Z

On 2020/4/24 17:54, Paraschiv, Andra-Irina wrote:
>
>
> On 24/04/2020 11:19, Paraschiv, Andra-Irina wrote:
>>
>>
>> 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.
>
> And just to be a bit more clear, the reply above takes into consideration that
> it's not emulated in QEMU.
>

Thanks.

Guys in this thread are much more interested in the design of enclave VM and the
new device, but there's no any document about this device yet, so I think the
emulate code is a good alternative. However, Alex said the device specific will
be published later, so I'll wait for it.

>
> 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.
---
Regards,
Longpeng(Mike)