Add a core_scheduling option to --cpus with three modes of operation.
This feature takes advantage of a kernel feature that restricts
scheduling of processes on the SMT threads on the same core. This is
useful for mitigating certain classes of side-channel attacks and has
better performance that disabling SMT on the CPU.
- vm (default): All vCPU threads share one core scheduling cookie.
They may be co-scheduled on SMT siblings while host threads are
excluded - this has minimal performance impact and can even
potentially improve performance from co-location.
- vcpu: Each vCPU gets a unique cookie preventing any two vCPUs from
sharing SMT siblings. This has the strongest isolation but at some
compromise of performance.
- off: No core scheduling applied (old behaviour).
This isolation is done by the kernel maintaining a "cookie" - threads
with the same cookie can share the same core.
In vCPU mode each vCPU thread the cookie is created when the thread
starts and each gets a unique cookie. For VM mode the first vCPU thread
(the leader) will create the cookie. All other vCPU threads started (via
hotplug or during boot) will have that cookie shared to it.
EINVAL/ENODEV from prctl is silently ignored so this works transparently
on kernels older than 5.14 that lack PR_SCHED_CORE or when SMT disabled.
Full details of this kernel feature can be found at:
https://docs.kernel.org/admin-guide/hw-vuln/core-scheduling.html
This implementation was inspired by crosvm's implementation - in
particular the enable_core_scheduling() function.
This is challenging to test via integration testing but the logging of
the received cookie shows it working:
VM case:
cloud-hypervisor: 0.243102s: <vcpu1> INFO:vmm/src/cpu.rs:1247 -- vCPU 1: core scheduling cookie = 0x33e4c167
cloud-hypervisor: 0.243102s: <vcpu0> INFO:vmm/src/cpu.rs:1247 -- vCPU 0: core scheduling cookie = 0x33e4c167
vCPU case:
cloud-hypervisor: 0.089356s: <vcpu0> INFO:vmm/src/cpu.rs:1247 -- vCPU 0: core scheduling cookie = 0x13993ad6
cloud-hypervisor: 0.089380s: <vcpu1> INFO:vmm/src/cpu.rs:1247 -- vCPU 1: core scheduling cookie = 0xd48e86e
Signed-off-by: Rob Bradford <rbradford@meta.com>
Add an image_type to DiskConfig to specify the image type. If none is
specified autodetect the image type but disable potentially unsafe
behaviour in the QCOW2 backend by disabling the backing file support.
If the image type is autodetected then fix it in the config so that it
will be persistant across reboots and migrations/snapshot & restores.
This also handles the case where the image type was not specified as
part of the disk configuration.
Signed-off-by: Rob Bradford <rbradford@meta.com>
TL;DR: cargo clippy|check|... now runs on whole workspace by default.
## Steps
- add new workspace member `cloud-hypervisor`
- move `./src` to new workspace member
- move `./tests` to new workspace member
- move relevant parts from Cargo.toml to new workspace member
- kept necessary parts in main Cargo.toml, such as profile
configurations
## About
The main Cargo.toml historically mixes workspace and crate definitions
for cloud-hypervisor and ch-remote. This makes it hard to read and
requires `--workspace` to run cargo clippy or cargo test on all
workspace members, which is counter-intuitive.
This patch separates the workspace from the crate definition in the main
Cargo.toml file. After this, cargo clippy, cargo test, etc., work on the
whole workspace naturally, giving a smoother developer experience. The
Cargo.toml without a package definition is also called a virtual
workspace or virtual manifest by Cargo [0].
Backporting is not a concern: CHV no longer backports, but the affected
files are rarely modified anyway.
[0] https://doc.rust-lang.org/cargo/reference/workspaces.html#virtual-workspace
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
