Hi,
The following is a breakdown (as best I can figure) of the work needed
to demonstrate VirtIO backends in Rust on the Xen hypervisor. It
requires work across a number of projects but notably core rust and virtio
enabling in the Xen project (building on the work EPAM has already done)
and the start of enabling rust-vmm crate to work with Xen.
The first demo is a fairly simple toy to exercise the direct hypercall
approach for a unikernel backend. On it's own it isn't super impressive
but hopefully serves as a proof of concept for the idea of having
backends running in a single exception level where latency will be
important.
The second is a much more ambitious bridge between Xen and vhost-user to
allow for re-use of the existing vhost-user backends with the bridge
acting as a proxy for what would usually be a full VMM in the type-2
hypervisor case. With that in mind the rust-vmm work is only aimed at
doing the device emulation and doesn't address the larger question of
how type-1 hypervisors can be integrated into the rust-vmm hypervisor
model.
A quick note about the estimates. They are exceedingly rough guesses
plucked out of the air and I would be grateful for feedback from the
appropriate domain experts on if I'm being overly optimistic or
pessimistic.
The links to the Stratos JIRA should be at least read accessible to all
although they contain the same information as the attached document
(albeit with nicer PNG renderings of my ASCII art ;-). There is a
Stratos sync-up call next Thursday:
https://calendar.google.com/event?action=TEMPLATE&tmeid=MWpidm5lbzM5NjlydnA…
and I'm sure there will also be discussion in the various projects
(hence the wide CC list). The Stratos calls are open to anyone who wants
to attend and we welcome feedback from all who are interested.
So on with the work breakdown:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
STRATOS PLANNING FOR 21 TO 22
Alex Bennée
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Table of Contents
─────────────────
1. Xen Rust Bindings ([STR-51])
.. 1. Upstream an "official" rust crate for Xen ([STR-52])
.. 2. Basic Hypervisor Interactions hypercalls ([STR-53])
.. 3. [#10] Access to XenStore service ([STR-54])
.. 4. VirtIO support hypercalls ([STR-55])
2. Xen Hypervisor Support for Stratos ([STR-56])
.. 1. Stable ABI for foreignmemory mapping to non-dom0 ([STR-57])
.. 2. Tweaks to tooling to launch VirtIO guests
3. rust-vmm support for Xen VirtIO ([STR-59])
.. 1. Make vm-memory Xen aware ([STR-60])
.. 2. Xen IO notification and IRQ injections ([STR-61])
4. Stratos Demos
.. 1. Rust based stubdomain monitor ([STR-62])
.. 2. Xen aware vhost-user master ([STR-63])
1 Xen Rust Bindings ([STR-51])
══════════════════════════════
There exists a [placeholder repository] with the start of a set of
x86_64 bindings for Xen and a very basic hello world uni-kernel
example. This forms the basis of the initial Xen Rust work and will be
available as a [xen-sys crate] via cargo.
[STR-51] <https://linaro.atlassian.net/browse/STR-51>
[placeholder repository] <https://gitlab.com/cardoe/oxerun.git>
[xen-sys crate] <https://crates.io/crates/xen-sys>
1.1 Upstream an "official" rust crate for Xen ([STR-52])
────────────────────────────────────────────────────────
To start with we will want an upstream location for future work to be
based upon. The intention is the crate is independent of the version
of Xen it runs on (above the baseline version chosen). This will
entail:
• ☐ agreeing with upstream the name/location for the source
• ☐ documenting the rules for the "stable" hypercall ABI
• ☐ establish an internal interface to elide between ioctl mediated
and direct hypercalls
• ☐ ensure the crate is multi-arch and has feature parity for arm64
As such we expect the implementation to be standalone, i.e. not
wrapping the existing Xen libraries for mediation. There should be a
close (1-to-1) mapping between the interfaces in the crate and the
eventual hypercall made to the hypervisor.
Estimate: 4w (elapsed likely longer due to discussion)
[STR-52] <https://linaro.atlassian.net/browse/STR-52>
1.2 Basic Hypervisor Interactions hypercalls ([STR-53])
───────────────────────────────────────────────────────
These are the bare minimum hypercalls implemented as both ioctl and
direct calls. These allow for a very basic binary to:
• ☐ console_io - output IO via the Xen console
• ☐ domctl stub - basic stub for domain control (different API?)
• ☐ sysctl stub - basic stub for system control (different API?)
The idea would be this provides enough hypercall interface to query
the list of domains and output their status via the xen console. There
is an open question about if the domctl and sysctl hypercalls are way
to go.
Estimate: 6w
[STR-53] <https://linaro.atlassian.net/browse/STR-53>
1.3 [#10] Access to XenStore service ([STR-54])
───────────────────────────────────────────────
This is a shared configuration storage space accessed via either Unix
sockets (on dom0) or via the Xenbus. This is used to access
configuration information for the domain.
Is this needed for a backend though? Can everything just be passed
direct on the command line?
Estimate: 4w
[STR-54] <https://linaro.atlassian.net/browse/STR-54>
1.4 VirtIO support hypercalls ([STR-55])
────────────────────────────────────────
These are the hypercalls that need to be implemented to support a
VirtIO backend. This includes the ability to map another guests memory
into the current domains address space, register to receive IOREQ
events when the guest knocks at the doorbell and inject kicks into the
guest. The hypercalls we need to support would be:
• ☐ dmop - device model ops (*_ioreq_server, setirq, nr_vpus)
• ☐ foreignmemory - map and unmap guest memory
The DMOP space is larger than what we need for an IOREQ backend so
I've based it just on what arch/arm/dm.c exports which is the subset
introduced for EPAM's virtio work.
Estimate: 12w
[STR-55] <https://linaro.atlassian.net/browse/STR-55>
2 Xen Hypervisor Support for Stratos ([STR-56])
═══════════════════════════════════════════════
These tasks include tasks needed to support the various different
deployments of Stratos components in Xen.
[STR-56] <https://linaro.atlassian.net/browse/STR-56>
2.1 Stable ABI for foreignmemory mapping to non-dom0 ([STR-57])
───────────────────────────────────────────────────────────────
Currently the foreign memory mapping support only works for dom0 due
to reference counting issues. If we are to support backends running in
their own domains this will need to get fixed.
Estimate: 8w
[STR-57] <https://linaro.atlassian.net/browse/STR-57>
2.2 Tweaks to tooling to launch VirtIO guests
─────────────────────────────────────────────
There might not be too much to do here. The EPAM work already did
something similar for their PoC for virtio-block. Essentially we need
to ensure:
• ☐ DT bindings are passed to the guest for virtio-mmio device
discovery
• ☐ Our rust backend can be instantiated before the domU is launched
This currently assumes the tools and the backend are running in dom0.
Estimate: 4w
3 rust-vmm support for Xen VirtIO ([STR-59])
════════════════════════════════════════════
This encompasses the tasks required to get a vhost-user server up and
running while interfacing to the Xen hypervisor. This will require the
xen-sys.rs crate for the actual interface to the hypervisor.
We need to work out how a Xen configuration option would be passed to
the various bits of rust-vmm when something is being built.
[STR-59] <https://linaro.atlassian.net/browse/STR-59>
3.1 Make vm-memory Xen aware ([STR-60])
───────────────────────────────────────
The vm-memory crate is the root crate for abstracting access to the
guests memory. It currently has multiple configuration builds to
handle difference between mmap on Windows and Unix. Although mmap
isn't directly exposed the public interfaces support a mmap like
interface. We would need to:
• ☐ work out how to expose foreign memory via the vm-memory mechanism
I'm not sure if this just means implementing the GuestMemory trait for
a GuestMemoryXen or if we need to present a mmap like interface.
Estimate: 8w
[STR-60] <https://linaro.atlassian.net/browse/STR-60>
3.2 Xen IO notification and IRQ injections ([STR-61])
─────────────────────────────────────────────────────
The KVM world provides for ioeventfd (notifications) and irqfd
(injection) to signal asynchronously between the guest and the
backend. As far a I can tell this is currently handled inside the
various VMMs which assume a KVM backend.
While the vhost-user slave code doesn't see the
register_ioevent/register_irqfd events it does deal with EventFDs
throughout the code. Perhaps the best approach here would be to create
a IOREQ crate that can create EventFD descriptors which can then be
passed to the slaves to use for notification and injection.
Otherwise there might be an argument for a new crate that can
encapsulate this behaviour for both KVM/ioeventd and Xen/IOREQ setups?
Estimate: 8w?
[STR-61] <https://linaro.atlassian.net/browse/STR-61>
4 Stratos Demos
═══════════════
These tasks cover the creation of demos that brig together all the
previous bits of work to demonstrate a new area of capability that has
been opened up by Stratos work.
4.1 Rust based stubdomain monitor ([STR-62])
────────────────────────────────────────────
This is a basic demo that is a proof of concept for a unikernel style
backend written in pure Rust. This work would be a useful precursor
for things such as the RTOS Dom0 on a safety island ([STR-11]) or as a
carrier for the virtio-scmi backend.
The monitor program will periodically poll the state of the other
domains and echo their status to the Xen console.
Estimate: 4w
#+name: stub-domain-example
#+begin_src ditaa :cmdline -o :file stub_domain_example.png
Dom0 | DomU | DomStub
| |
: /-------------\ :
| |cPNK | |
| | | |
| | | |
/------------------------------------\ | | GuestOS | |
|cPNK | | | | |
EL0 | Dom0 Userspace (xl tools, QEMU) | | | | | /---------------\
| | | | | | |cYEL |
\------------------------------------/ | | | | | |
+------------------------------------+ | | | | | Rust Monitor |
EL1 |cA1B Dom0 Kernel | | | | | | |
+------------------------------------+ | \-------------/ | \---------------/
-------------------------------------------------------------------------------=------------------
+-------------------------------------------------------------------------------------+
EL2 |cC02 Xen Hypervisor |
+-------------------------------------------------------------------------------------+
#+end_src
[STR-62] <https://linaro.atlassian.net/browse/STR-62>
[STR-11] <https://linaro.atlassian.net/browse/STR-11>
4.2 Xen aware vhost-user master ([STR-63])
──────────────────────────────────────────
Usually the master side of a vhost-user system is embedded directly in
the VMM itself. However in a Xen deployment their is no overarching
VMM but a series of utility programs that query the hypervisor
directly. The Xen tooling is also responsible for setting up any
support processes that are responsible for emulating HW for the guest.
The task aims to bridge the gap between Xen's normal HW emulation path
(ioreq) and VirtIO's userspace device emulation (vhost-user). The
process would be started with some information on where the
virtio-mmio address space is and what the slave binary will be. It
will then:
• map the guest into Dom0 userspace and attach to a MemFD
• register the appropriate memory regions as IOREQ regions with Xen
• create EventFD channels for the virtio kick notifications (one each
way)
• spawn the vhost-user slave process and mediate the notifications and
kicks between the slave and Xen itself
#+name: xen-vhost-user-master
#+begin_src ditaa :cmdline -o :file xen_vhost_user_master.png
Dom0 DomU
|
|
|
|
|
|
+-------------------+ +-------------------+ |
| |----------->| | |
| vhost-user | vhost-user | vhost-user | : /------------------------------------\
| slave | protocol | master | | | |
| (existing) |<-----------| (rust) | | | |
+-------------------+ +-------------------+ | | |
^ ^ | ^ | | Guest Userspace |
| | | | | | |
| | | IOREQ | | | |
| | | | | | |
v v V | | \------------------------------------/
+---------------------------------------------------+ | +------------------------------------+
| ^ ^ | ioctl ^ | | | |
| | iofd/irqfd eventFD | | | | | | Guest Kernel |
| +---------------------------+ | | | | | +-------------+ |
| | | | | | | virtio-dev | |
| Host Kernel V | | | | +-------------+ |
+---------------------------------------------------+ | +------------------------------------+
| ^ | | ^
| hyper | | |
----------------------=------------- | -=--- | ----=------ | -----=- | --------=------------------
| call | Trap | | IRQ
V | V |
+-------------------------------------------------------------------------------------+
| | ^ | ^ |
| | +-------------+ | |
EL2 | Xen Hypervisor | | |
| +-------------------------------+ |
| |
+-------------------------------------------------------------------------------------+
#+end_src
[STR-63] <https://linaro.atlassian.net/browse/STR-63>
--
Alex Bennée
Hi Bartosz,
This patch adds rust bindings for libgpiod v2.0, this is already partially
tested with the virtio rust backend I am developing, which uses these to talk to
the host kernel.
This is based of the next/post-libgpiod-2.0 branch.
I haven't added any mock test for this as of now and I am not sure how exactly
am I required to add them. I did see what you mentioned in your patchset about
mock-test vs gpio-sim stuff. Rust also have its own test-framework and I am not
sure if that should be used instead or something else.
Since I am posting this publicly for the first time, it is still named as V1. I
have not made significant changes to the code since last time, but just divided
the same into multiple files.
--
Viresh
Viresh Kumar (2):
libgpiod: Generate rust FFI bindings
libgpiod: Add rust wrappers
.gitignore | 6 +
bindings/rust/Cargo.toml | 14 +
bindings/rust/build.rs | 60 ++++
bindings/rust/src/bindings.rs | 16 ++
bindings/rust/src/chip.rs | 197 +++++++++++++
bindings/rust/src/edge_event.rs | 78 +++++
bindings/rust/src/event_buffer.rs | 59 ++++
bindings/rust/src/info_event.rs | 70 +++++
bindings/rust/src/lib.rs | 268 +++++++++++++++++
bindings/rust/src/line_config.rs | 431 ++++++++++++++++++++++++++++
bindings/rust/src/line_info.rs | 186 ++++++++++++
bindings/rust/src/line_request.rs | 218 ++++++++++++++
bindings/rust/src/request_config.rs | 118 ++++++++
bindings/rust/wrapper.h | 2 +
14 files changed, 1723 insertions(+)
create mode 100644 bindings/rust/Cargo.toml
create mode 100644 bindings/rust/build.rs
create mode 100644 bindings/rust/src/bindings.rs
create mode 100644 bindings/rust/src/chip.rs
create mode 100644 bindings/rust/src/edge_event.rs
create mode 100644 bindings/rust/src/event_buffer.rs
create mode 100644 bindings/rust/src/info_event.rs
create mode 100644 bindings/rust/src/lib.rs
create mode 100644 bindings/rust/src/line_config.rs
create mode 100644 bindings/rust/src/line_info.rs
create mode 100644 bindings/rust/src/line_request.rs
create mode 100644 bindings/rust/src/request_config.rs
create mode 100644 bindings/rust/wrapper.h
--
2.31.1.272.g89b43f80a514
Hi Ilias/Akashi-san,
So after the call earlier this week Mike asked me to write-up a EPIC for
the measurement work. I think this covers the deployments we want to
measure but any feedback is welcome. The Xen documentation talks rather
euphemistically about Open vSwitch but I don't know if that is just the
management name for using the same network routing internals as the
other ePPF ones.
Anyway any thoughts?
━━━━━━━━━━━━━━━━━━━━━━━
STRATOS XDP MEASURING
Alex Bennée
━━━━━━━━━━━━━━━━━━━━━━━
Table of Contents
─────────────────
1. Abstract
2. Networking Setups
.. 1. Test Setup
.. 2. Potential Packet Paths
.. 3. Host Networking
.. 4. KVM Guest with vhost networking
.. 5. Pass-through (SR-IOV or virtualised HW)
.. 6. Open vSwitch routing (Xen)
1 Abstract
══════════
As we move network endpoints into different VM configurations we need
to understand the costs and latency effects those choices will have.
With that understanding we can then consider various approaches to
optimising packet flow through virtual machines.
2 Networking Setups
═══════════════════
2.1 Test Setup
──────────────
The test setup will require two machines. The test controller will be
the source of the test packets and measure the round trip latency to
get a reply from the test client. The test client will be setup in
multiple configurations so the latency can be checked.
+-----------------------+ +-----------------------+
|c1AB | |c1AB |
| Test Control | | Test Client |
| | | |
+-+--------+-+--------+-+ +-+--------+-+--------+-+
|{mo} | |{mo} | |{mo} | |{mo} |
| eth0 | | eth1 | | eth1 | | eth0 |
|cRED | |cPNK | |cPNK | |cRED |
+--------+ +--------+ +--------+ +--------+
| ^ ^ |
| | test link | |
: +---------------------------+ :
| 10GbE |
| |
/--------------------------------------------=-----------\
| LAN |
\---------------------------------------------=----------/
2.2 Potential Packet Paths
──────────────────────────
For each experiment we need to measure the latency of 3 different
packet reflectors. A simple ping pong running either via:
• xdp_xmit - lowest latency turnaround at the driver
• xdp_redir - bypass linux networking stack to user-space
• xpd_pass - normal packet path to conventional AF_INET socket
+--------------------------------------------------------------------------+
|cDED |
| /---------------\ /---------------\ |
| |cGRE | |cGRE | |
| | Test | | Test | |
| | Program | | Program | |
| | | | | |
| +---------------+ +---------------+ user-space |
| |cYEL | |cCEF | |
| | AF_INET | | AF_XDP | |
| | | | | |
| +---------------+ +---------------+ |
| ^ ^ |
| | | |
| : : |
+--------------------------------------------------------------------------+
: :
| |
+--------------------------------------------------------------------------+
|cBAD | | |
| +---------------+ : 2. xdp_redir |
| |cYEL | | kernel-space |
| | | 3. xdp_pass +---------+ |
| | Linux | <-----=------ | XDP | ---=----+ |
| | Networking | +----+---------+----+ | 1. xdp_xmit |
| | stack | |cRED | | |
| | | | Driver | <--+ |
| | | | | |
| \---------------/ \-------------------/ |
| |
+--------------------------------------------------------------------------+
2.3 Host Networking
───────────────────
This is the default case with no virtualisation involved.
/---------------------\
|cGRE |
| Network Test | Host User Space
| Program |
| |
+---------------------+
+------------------------------------------------+
| +---------------------+ |
| |cYEL | |
| | Packet Routing | |
SW | | | |
| +---------------------+ Host Kernel Space |
| |cRED | |
| | Driver | |
| | | |
| \---------------------/ |
+------------------------------------------------+
----=-----------------------------------------------------------------------------------------
+---------------------+
|{mo} |
HW | Network |
| Card |
|c444 |
+---------------------+
2.4 KVM Guest with vhost networking
───────────────────────────────────
This is a KVM only case where the vhost device allows packets to be
delivered directly from the guest kernels address space. It still
relies on the host kernels networking stack though.
|
| /------------\
| |cGRE |
| | | Guest User
| +------------+
| ----------------=------
| +------------+
| |cYEL |
: +------------+ Guest Kernel
| |cRED |
| | virtio-net |
| +------------+
+------------------------------------------------+
| +---------------------+---------------------+ |
| |cYEL |cPNK vhost-virtio | |
| | Packet Routing +---------------------/ |
SW | | | |
| +---------------------+ Host Kernel Space |
| |cRED | |
| | Driver | |
| | | |
| \---------------------/ |
+------------------------------------------------+
----=------------------------------------------------------
+---------------------+
|{mo} |
HW | Network |
| Card |
|c444 |
+---------------------+
2.5 Pass-through (SR-IOV or virtualised HW)
───────────────────────────────────────────
Either using direct pass-through to a discrete ethernet device or a
virtualised function. The control of the packet starts and ends in the
guests kernel.
Host System/Dom0 Guest VM/DomU
| /---------\
| |cGRE |
/---------------------\ | /-----------+---------+
|cBAD Kernel | : |cBAD |cYEL |
\---------------------/ | \-----------+---------+
+-------------------------------------+ |cRED |
|cB9C Hypervisor | | Driver |
+-------------------------------------+ +---------/
----=------------------------------------------------------
+---------------+ +---------------+
|{mo} | |{mo} |
HW | NIC | | vNIC |
|c444 | |c544 |
+---------------+ +---------------+
2.6 Open vSwitch routing (Xen)
──────────────────────────────
Here the packets are switched into paravirtualized Xen interfaces by
the Dom0 kernel. I'm a little unsure as to what Open vSwitch uses to
route stuff and if it's the same as the existing eBPF stuff.
|
|
Dom0/Host : DomU Guest
|
|
| /-----------\
| |cGRE | Guest
| | | User
+------------------------------------------------+ | +-+-----------+---------------+
| +-----------------------------------------+ | | | +-------+ |
SW | |cYEL Open vSwitch | | | | |cYEL | |
| +---------------------+-----------+-------+ | | | +-------+ Guest |
| |cRED | |cPNK | | | | |cRED | Kernel |
| | Driver | | XenPV |<-=|-=|=-|=->| XenPV | |
| | | | BE | | | | | FE | |
| \---------------------/ \-------+ | | | +-------/ |
+------------------------------------------------+ | +-----------------------------+
+------------------------------------------------------------------------------------+
|cB9C Hypervisor |
+------------------------------------------------------------------------------------+
-----------------------------------------------------------------------------------------------=------------
+---------------------+
|{mo} |
HW | Network |
| Card |
|c444 |
+---------------------+
--
Alex Bennée
Hi,
Any topics to be added to the agenda for tomorrows sync-up call. I
should have the AF_XDP cards done and hopefully we will have another
topic to discuss as well.
--
Alex Bennée
Hi Bartosz/Miguel,
Here is another attempt to add rust wrappers for libgpiod, hopefully it would
look much better this time.
V1->V2
- Propagate proper errors returned by the kernel to the user. Improved error
handling overall.
- Improved Enum support, with their own helpers to reduce redundant code.
- Improved names for methods of various structures, they are updated to match
the underlying libgpiod helpers.
- SAFETY comments added to methods that return strings.
- Based off next/post-libgpiod-2.0 branch.
--
Viresh
Viresh Kumar (2):
libgpiod: Generate rust FFI bindings
libgpiod: Add rust wrappers
.gitignore | 7 +
Cargo.toml | 14 +
build.rs | 60 ++
src/bindings.h | 3 +
src/bindings.rs | 16 +
src/lib.rs | 1474 +++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 1574 insertions(+)
create mode 100644 Cargo.toml
create mode 100644 build.rs
create mode 100644 src/bindings.h
create mode 100644 src/bindings.rs
create mode 100644 src/lib.rs
--
2.31.1.272.g89b43f80a514
Hi,
Any topics to cover?
I know there are some bits that should be ready for the next sync-up and
we have some holiday clashes tomorrow.
--
Alex Bennée
