The VmConfig that arrives over the migration stream carries the
source's device paths and stale FDs, none of which are usable on the
destination. A received VFIO device therefore needs fresh descriptors
supplied with the request.
VmReceiveMigrationData gains vfio_fds, pairing each device id with a
cdev FD, and iommufd_fd for the backing iommufd, both arriving over
SCM_RIGHTS. Once the received VmConfig is available, each named
device's path or FD is swapped for the received one and the iommufd is
installed before the VM is built, so the device comes up FD backed.
The request is rejected when a substituted device lacks the iommufd
backend, when an id is unknown or repeated, or when a device names no
replacement in vfio_fds. These checks run against the migrated VmConfig
once it has been received.
ch-remote gains the vfio_fds and iommufd_fd options and forwards the
descriptors over SCM_RIGHTS. The D-Bus transport cannot carry file
descriptors and drops them.
Signed-off-by: Saravanan D <saravanand@crusoe.ai>
A VFIO device restored onto a different host has a device path and
iommufd that are meaningless there, and an FD backed device cannot
serialize a live descriptor into the snapshot at all. Restoring one
therefore needs fresh descriptors supplied with the request.
RestoreConfig gains vfio_fds, pairing each device id with a cdev FD,
and iommufd_fd for the backing iommufd. Both arrive over SCM_RIGHTS on
the restore request. vm_restore swaps each named device's stale path
or FD for the received one and installs the iommufd before the VM is
built, so the device comes up FD backed.
The request is rejected when a substituted device lacks the iommufd
backend, when an id is unknown or repeated, or when an FD backed device
names no replacement.
ch-remote gains the vfio_fds and iommufd_fd options and forwards the
descriptors through the SCM_RIGHTS pool.
Signed-off-by: Saravanan D <saravanand@crusoe.ai>
Import the modules used in the crate instead of spelling the full paths
at every use site, and drop the now-unnecessary crate-level
Signed-off-by: Henry Hrvoje Tonkovac <htonkovac@gmail.com>
Assisted-by: Claude:Opus-4.8
The HTTP API mapped every ApiError to 500 Internal Server Error, so an
API client could not distinguish "the VM has not been created yet" from
a genuine server-side failure without parsing the error message text.
Derive the HTTP status code from the error itself in error_response():
errors whose root cause is VmError::VmNotCreated or VmMissingConfig are
now reported as 404 Not Found, regardless of which API action surfaced
them. The existing 400 (bad request) and 429 (too many requests)
mappings are preserved.
State-conflict errors such as VmNotRunning would ideally map to 409
Conflict, but micro_http's StatusCode has no Conflict variant, so they
remain 500 for now.
Fixes: #7774
Signed-off-by: Max Makarov <maxpain@linux.com>
Assisted-by: Claude:claude-opus-4-8 [Claude Code]
Switch NetConfig over to using the newly extracted struct members as
used by all PCI based devices. The use of #[serde(flatten)] means that
this change has no impact on the JSON format that the data is stored as.
Signed-off-by: Rob Bradford <rbradford@meta.com>
## TL;DR
This unifies error handling, implementation, and logging of config
objects that are populated with additional FDs received as part of
the HTTP API request from the management software. This prevents current
and future code in repetition.
In the future, if we want to support let's say virtio-blk with external
FDs, the AddBlk API handler simply needs a call to `attach_fds_to_cfg()`
and gets all the magic for free.
## Motivation
The motivation of the new abstraction is to provide a verbose, solid,
and bulletproof solution for a complex domain. The interaction between
- the management layer,
- the passing of file descriptors over UNIX domain sockets via
SCM_RIGHTS,
- the attachment of configurations to those FDs,
- and the ability to give new developers clear insights into what
happens under the hood
is not trivial. These factors justify encapsulating the complexity
behind a convenient and well-documented abstraction, making the system
both robust in production and approachable for new developers.
In addition, it allows us to perform unit testing. Further, We get rid
of existing partial code duplication and inconsistencies.
Finally, while this approach may initially result in more code, every
new handler that accepts FDs benefits from reduced duplication and a
correct implementation by relying on the shared abstraction. This will
also enable future functionality, such as virtio-blk devices backed by
FDs which can then be integrated with ease.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
Live migration, state save/resume, and hotplug are not trivial when it
comes to virtio-net devices backed by externally provided FDs. As the
mechanism behind it can be considered as quite "multi-step magic" even
for experienced programmers, it makes sense to thoroughly document this
to ease debugging and to improve the mental model of developers working
on this in the future.
Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com
Although the CPU manager gives us a quite descriptive error, on the
application side (the part calling Cloud Hypervisor) we have absolutely
no way to distinguish such error from any other error that may happen
when resizing a VM.
With this in mind, let's be more specific and return a TooManyRequests
(429) error, allowing the caller to have a chance to decide whether they
want to retry the operation or not.
https://datatracker.ietf.org/doc/html/rfc6585#section-4
Signed-off-by: Fabiano Fidêncio <fidencio@northflank.com>
This patch removes pub import vm_config in config.rs to eliminate
the ambiguity of vm_comfig reference.
Signed-off-by: Songqian Li <sionli@tencent.com>
Historically the Cloud Hypervisor coding style has been to ensure that
all imports are ordered and placed in a single group. Unfortunately
cargo fmt has no support for ensuring that all imports are in a single
group so if whitespace lines were added as part of the import statements
then they would only be odered correctly in the group.
By adopting "group_imports="StdExternalCrate" we can enforce a style
where imports are placed in at most three groups for std, external
crates and the crate itself. Choosing a style enforceable by the tooling
reduces the reviewer burden.
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
This patch removes locks in VmCreate request and VmInfo response
since we needn't use a lock here and should ensure that internal
implementation is transparent to the runtime.
Signed-off-by: Songqian Li <sionli@tencent.com>
Consume FDs passed via SCM_RIGHTs to VmRestore API and assign them
appropriately to RestoredNetConfig's fds field.
Signed-off-by: Purna Pavan Chandra <paekkaladevi@linux.microsoft.com>
Uses of the old ApiRequest enum conflated two different concerns:
identifying an API request endpoint, and storing data for an API
request. This led to ApiRequest values being passed around with junk
data just to communicate a request type, which forced all API request
body types to implement Default, which in some cases doesn't make any
sense — what's the "default" path for a vhost-user socket? The
nonsensical Default values have led to tests relying on being able to
use nonsensical data, which is an impediment to adding better
validation for these types.
Rather than having API request types be represented by an enum, which
has to carry associated body data everywhere it's used, it makes more
sense to represent API request types as trait objects. These can have
an associated type for the type of the request body, and this makes it
possible to pass API request types and data around as siblings in a
type-safe way without forcing them into a single value even where it
doesn't make sense. Trait objects also give us dynamic dispatch,
which lets us get rid of several large match blocks.
To keep it possible to fuzz the HTTP API, all the Vmm methods called
by the HTTP API are pulled out into a trait, so the fuzzer can provide
its own stub implementation of the VMM.
Signed-off-by: Alyssa Ross <hi@alyssa.is>
This does the same thing as df2a7c17 ("vmm: Ignore and warn TAP FDs
sent via the HTTP request body"), but for the vm.create endpoint,
which also previously would accept file descriptors in the body, and
try to use whatever fd occupied that number as a TAP device.
Signed-off-by: Alyssa Ross <hi@alyssa.is>
