This talk will cover the latest Xen features that have been introduced in recent releases. This includes Xen on ARM, the new x86 PVH virtualization mode and many other exiting features. The talk will also contain tips about how to correctly setup and use Xen efficiently in production environments, with performance and security in mind. Author Biography Roger Pau Monne is a Software Engineer at Citrix and a FreeBSD developer. He is currently working on maintaining and improving Xen support in FreeBSD, focusing mainly on PVH and Dom0. He also contributes to other Xen-related projects, like the Xen Hypervisor itself, the Linux kernel and Qemu.

1. What’s Going on in Xen
Status update of the Xen Project
Roger Pau Monn´e
Barcelona – October 21, 2015

2. Goals Xen overview Xen community Xen’s new features Conclusions
Goals of this presentation
Description of Xen.
Understanding how the Xen community works.
A peek into Xen’s new features.
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3. Goals Xen overview Xen community Xen’s new features Conclusions
Xen Architecture (type-1 hypervisor)
Hardware CPU MMU ...
Xen
syslog
xterm
xorg
...
Guest 1
Control
Domain
Linux, FreeBSD
or NetBSD
Guest 2
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4. Goals Xen overview Xen community Xen’s new features Conclusions
Type-2 hypervisor architecture
Hardware CPU MMU ...
syslog
xterm
xorg
...
Guest 1 Guest 2
Operating System
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5. Goals Xen overview Xen community Xen’s new features Conclusions
Paravirtualization
Virtualization technique developed in the late 90s.
Designed by:
XenoServer research project at Cambridge University.
Intel.
Microsoft labs.
x86 instructions behave differently in kernel or user mode,
options for virtualization were full software emulation or
binary translation.
Design a new interface for virtualization.
Allow guests to collaborate in virtualization.
Provide new interfaces for virtualized guests that allow to
reduce the overhead of virtualization.
The result of this work is what we know today as
paravirtualiztion.
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6. Goals Xen overview Xen community Xen’s new features Conclusions
Paravirtualization
All this changes lead to the following interfaces being
paravirtualized:
Disk and network interfaces
Interrupts and timers
Boot directly in the mode the kernel wishes to run (32 or
64bits)
Page tables
Privileged instructions
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7. Goals Xen overview Xen community Xen’s new features Conclusions
Full virtualization
With the introduction of hardware virtualization extensions
Xen is able to run unmodified guests
This requires emulated devices, which are handled by Qemu
Makes use of nested page tables when available.
Allows to use PV interfaces if guest has support for them.
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8. Goals Xen overview Xen community Xen’s new features Conclusions
New x86 virtualization mode: PVH
PV in an HVM container.
PVH should use the best aspects from both PV and HVM:
No need for any emulation.
Has a ”native” MMU from guest point of view.
Has access to the same protection levels as bare metal.
Written by Mukesh Rathor @ Oracle.
Significant revisions by George Dunlap @ Citrix.
Currently the internals of PVH in Xen are being rewritten.
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9. Goals Xen overview Xen community Xen’s new features Conclusions
The virtualization spectrum
VS Software virtualization
VH Hardware virtualization
PV Paravirtualized
Poor performance
Room for improvement
Optimal performance
D
isk
and
network
Interrupts
and
tim
ers
Em
ulated
m
otherboard
Privileged
instructions
and
page
tables
HVM VS VS VS VH
HVM with PV drivers PV VS VS VH
PVHVM PV PV VS VH
PVH PV PV PV VH
PV PV PV PV PV
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10. Goals Xen overview Xen community Xen’s new features Conclusions
Xen community overview
The Xen Hypervisor was released under the GPL2 on 2003.
The Xen Project became a Linux Foundation Collaborative
Project in 2013.
Xen Project teams:
Xen Hypervisor.
ARM Hypervisor.
XAPI.
Mirage OS.
Linux PVOPS.
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11. Goals Xen overview Xen community Xen’s new features Conclusions
Xen governance
Roles:
Maintainers: own one or more components in the Xen source
tree.
Committers: maintainers that are allowed to commit changes
into the source code repository.
Sub-projects and teams: run by individuals, projects are related
or based on the Xen Project.
See http:
//www.xenproject.org/developers/governance.html
for more information.
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12. Goals Xen overview Xen community Xen’s new features Conclusions
Xen Hypervisor
Main project, contains the hypervisor and the toolstack.
Led by 5 committers; 2 from Citrix, 1 from Suse, 1 from
Oracle, 2 Independent.
During the 4.6 release cycle the Xen Project had contributions
from 96 individuals from 30 organizations.
Organizations that contributed to the 4.6 release: Citrix,
SUSE, Intel, Oracle, Linaro, Fujitsu...
Full list can be found at http://wiki.xen.org/wiki/Xen_
Project_4.6_Acknowledgements.
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13. Goals Xen overview Xen community Xen’s new features Conclusions
Xen’s new features
Xen 4.6 released one week ago:
Improved and extended the memory event subsystem.
Improved the default XSM policy and added support for
testing it in OSStest.
vTPM 2.0 support.
Improved grant table scalability.
New locking mechanism to improve fairness (ticket locks).
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14. Goals Xen overview Xen community Xen’s new features Conclusions
x86 specific improvements
Support for several new features in upcoming Intel processors:
alternate P2M, page modification logging, cache allocation
and memory bandwidth monitoring.
Support for profiling Xen using a performance monitoring unit
(PMU).
Virtual NUMA topology for Xen guests.
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15. Goals Xen overview Xen community Xen’s new features Conclusions
ARM specific improvements
Supported number of vCPUs increased from 8 to 128.
Passthrough of non-PCI devices.
GICv2 on GICv3 support.
OVMF support (UEFI for guests).
Support for guests running with 64KB pages.
Support for new platforms: Renesas R-Car Gen2, Thunder X,
Huawei hip04-d04 and Xilinx ZynqMP SoC.
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16. Goals Xen overview Xen community Xen’s new features Conclusions
Toolstack updates
New live migration implementation (Migration v2).
Remus (HA on top of Xen) reworked on top of Migration v2.
Improved Spice/QXL support.
Xenalyze merged into Xen codebase.
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17. Goals Xen overview Xen community Xen’s new features Conclusions
Test lab
Moved the Xen test infrastructure to a new lab.
Funded by the Xen Project advisory board, currently with 24
dedicated hosts.
Expanded test coverage: XSM, libvirt...
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18. Goals Xen overview Xen community Xen’s new features Conclusions
OS related updates
Linux:
Added multipage support to blkfront.
Added xen-scsi support.
Performance improvements.
PV guests can support up to 512GB of RAM.
FreeBSD:
PVH DomU/Dom0 support.
Removal of the i386 PV port.
Support for indirect descriptors in blkfront.
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19. Goals Xen overview Xen community Xen’s new features Conclusions
The Xen Project status
The 4.6 release has been the one with the best quality and
quantity of commits so far.
The Xen Project ecosystem is a very active community with
contributions from a wide array of companies and individuals.
First release to be completely on time.
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20. Goals Xen overview Xen community Xen’s new features Conclusions
Q&A
Thanks
Questions?
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