xen and the art of embedded virtualization (elc 2017)

Stefano Stabellini @stabellinist

Xen on ARM,and the Art of Embedded Virtualization

Security, Isolation, Partitioning

Why Xen?Why an hypervisor?

Galois SMACCMPPilot

Demo

Xen Summit 2014

Why Xen?

• Efficiency and Consolidation• Isolation and Partitioning• Componentization• Resilience• Scaling• Portability

Xen: a type-1 hypervisor

Hardware

Xen

Dom0 DomU

HW drivers

PV backends PV Frontends

DomU

PV Frontends

DomU

PV Frontends

Xen: the gears of the cloud

• Large user base (> 10M individual users)

• Powers the largest clouds in production

• Not just servers

Xen: Open Source

Xen: Open Source

partial

Embedded != Cloud

Different requirements:

• short boot times• small footprint• small codebase (certifications)• non-PCI device assignment• driver domains• low, deterministic irq latency• real time schedulers• co-processor virtualization

Xen on ARM

• A lean and simple architecture– No cruft– No emulation, No QEMU– Small attack surface– One type of guest

• Exploit the hardware as much as possible• A very good match for the hardware• Clean architecture = a very small code base

– Xen, ARM and ARM64 =~ 30K LOC

Xen on ARM: a perfect match for the HW

Xen on ARM: unique features

• Device Passthrough (even Non-Discoverable Devices)– iomem and irqs VM config parameters

• No guest firmware by default - fast VM boot

• Certifications efforts ongoing

• Low, Deterministic IRQ latency (WARM_MAX < 2000ns)

Low IRQ latency: no maintenance interrupts

DomU

Xen

irq 109

virq 109

DomU

Xen

EOI

DomU

Xen

Maintenance interrupt

GICH_LRWrite

GICH_LRClear

Low IRQ latency: physical follow virtual

vcpu0 vcpu1

pcpu0 pcpu1

irq 109

virq 109

Low IRQ latency: physical follow virtual

vcpu0 vcpu1

pcpu0 pcpu1

irq 109

virq 109

Low IRQ latency: physical follow virtual

vcpu0 vcpu1

pcpu0 pcpu1

irq 109

virq 109

Xen Schedulers

CPU CPU CPU CPU

CPU CPU CPU CPU

Xen Schedulers

CPU CPU CPU CPU

CPU CPU CPU CPU

Real Time SchedulerARINC 653

Regular VM SchedulerCredit

Dedicatedto 1 VCPU

Dedicatedto 1 VCPU

Memory Introspection

PV Protocols

Existing: net, block, console, keyboard, mouse, framebuffer, XenGT

New: 9pfs, PVCalls, Multi Touch, Sound, Display

Driver Domains

Hardware

Xen

Dom0 DomU

NetFront

Disk Driver Domain

Toolstack Disk Driver

BlockBack

Network Driver

Domain

Network Driver

NetBack BlockFront

Automotive

Hardware

Xen

Dom0Linux Control Domain

UI DomainAutomotive Grade Android

HW Drivers GPU Driver

PV Block & Net frontends

PV Block & Net Backends

AudioDriver

GlobalLogic

EPAMEPAM

EPAM: DEMO

https://www.youtube.com/watch?v=jMmz1odBZb8

Xilinx Zynq MPSoC

Xen

Dom0Linux

Baremetal App

Toolstack FPGA Driver

Baremetal App

FPGA Driver

Baremetal App

FPGA Driver

Baremetal App

FPGA Driver

FPGA

Dedicated CPU Dedicated CPU Dedicated CPU Dedicated CPU

Xen: best security process in the industry

• A very transparent process

• Responsible disclosure

• Few security issues for Xen on ARM

• Xen stable trees maintained for security for 3 years

Release process

• 6 month release– December– June

• Xen 4.8 released on the 5th of December 2016• Xen 4.9 planned for the 2nd of June 2017

Xen on ARM: what’s next

● Guest creation directly from Xen at boot via Device Tree● Dynamic Memory Map● Setup VM-to-VM communication channels from VM

config

More resources

• Port Xen to a new SOC: https://goo.gl/384aD8• Add Xen support Xen to your OS: https://goo.gl/3qgqcM• Xen on ARM whitepaper: https://goo.gl/TcuqXd• Xen on ARM wiki: https://goo.gl/9qsfMf• Device Passthrough presentation: https://goo.gl/KM0f8c• OE meta-virtualization Xen recipe:

https://goo.gl/m7GuXR• OpenXT (Xen + OpenEmbedded): http://openxt.org• Biweekly ARM Community Call: https://goo.gl/8ULYRn

Please engage!

• Xen devel ML: xen-devel@lists.xenproject.org• Xen user ML: xen-users@lists.xenproject.org• IRC on freenode: #xenarm or #xen-devel

Fin