Add snapsafety features to VMClock device #5564
Draft
+1,523
−90
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
bchalios
force-pushed
the
vmclock-snapsafe
branch
from
6818148 to
81dbeb2
Compare
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #5564 +/- ##
=======================================
Coverage 83.23% 83.24%
=======================================
Files 277 277
Lines 29265 29310 +45
=======================================
+ Hits 24359 24399 +40
- Misses 4906 4911 +5
Flags with carried forward coverage won't be shown. Click here to find out more. ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
|
bchalios
force-pushed
the
vmclock-snapsafe
branch
8 times, most recently
from
5487e22 to
115a1d6
Compare
Add support for vm_generation_counter and notifications. Keep this separately for now, since currently upstream bindings don't include it. We will recreate this for Linux headers once they are released. Signed-off-by: Babis Chalios <[email protected]>
Add support for `vm_generation_counter` field in VMClock ABI. This field is similar to `disruption_marker` but it's only updated on snapshot loading events (not in live migration). It is meant to provide the guest with snapshot safety notifications. Moreover, add support for the notification capability. This capability require us to send an ACPI notification every time we change the seq_count field to a new even value. This essentially means that we need to send a notification upon resuming from a snapshot just before resuming vCPUs. Signed-off-by: Babis Chalios <[email protected]>
Extend VMClock integration tests to also account for the vm_generation_counter field and notification support flag. Signed-off-by: Babis Chalios <[email protected]>
Expose VMClock device to guest via DT and enable compiling the vmclock for ARM architectures. Keep VMClock tests only on x86 until we get support from the guest kernel. Signed-off-by: Babis Chalios <[email protected]>
Add support to apply patches while build kernels for our CI. For the time being we use this to apply patches for snapshot safety VMClock extensions [1] (backported to 5.10 and 6.1 AL kernels). [1] https://lkml.org/lkml/2025/12/3/653 Signed-off-by: Babis Chalios <[email protected]>
Enable CONFIG_PTP_1588_CLOCK_VMCLOCK for both 5.10 and 6.1 kernels Signed-off-by: Babis Chalios <[email protected]>
We now apply backported patches that add support for VMClock on Aarch64 systems via DT bindings, so enable tests for Aarch64 as well. Moreover, backported patches add support for the poll() system calls family, so enable the relevant test. Signed-off-by: Babis Chalios <[email protected]>
bchalios
force-pushed
the
vmclock-snapsafe
branch
from
115a1d6 to
99d68b0
Compare
Manciukic
reviewed
Dec 10, 2025
| pub const VMCLOCK_FLAG_TIME_ESTERROR_VALID: u64 = 32; | ||
| pub const VMCLOCK_FLAG_TIME_MAXERROR_VALID: u64 = 64; | ||
| pub const VMCLOCK_FLAG_TIME_MONOTONIC: u64 = 128; | ||
| pub const VMCLOCK_FLAG_VM_GEN_COUNTER_PRESENT: u64 = 256; |
Contributor
There was a problem hiding this comment.
should we add this to our bindgen patches?
Comment on lines
+203
to
+207
| # Undo any patches previsouly applied, so that we can build the same kernel with different | ||
| # configs, e.g. no-acpi | ||
| git reset --hard $(get_tag $KERNEL_VERSION) | ||
| git clean -f -d | ||
|
|
Contributor
There was a problem hiding this comment.
should we just create a temporary branch for the build? iow replace
- git checkout $(get_tag $KERNEL_VERSION)
+ git checkout -B tmp $(get_tag $KERNEL_VERSION)
| # Enable PHYLIB and NETWORK_PHY_TIMESTAMPING to see the additional clocks. | ||
| # | ||
| CONFIG_PTP_1588_CLOCK_KVM=y | ||
| CONFIG_PTP_1588_CLOCK_VMCLOCK=y |
Contributor
There was a problem hiding this comment.
I think we should have this in our patches on top of this base config, otherwise we risk removing these when we rebase the config.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Changes
Implement snapshot safety features for VMClock device as described in this Linux patchset: https://lore.kernel.org/lkml/[email protected]/.
Expose the
vm_generation_counterfield in thevmclock_abi. Also, implement the notification feature. This simply means that during snapshot resume we bumpvm_gneration_counterand inject an interrupt to the guest before resuming vCPUs.Reason
Provide a means for the guest userspace to know that the microVM has been loaded from a snpahost
License Acceptance
By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache 2.0 license. For more information on following Developer
Certificate of Origin and signing off your commits, please check
CONTRIBUTING.md.PR Checklist
tools/devtool checkbuild --allto verify that the PR passesbuild checks on all supported architectures.
tools/devtool checkstyleto verify that the PR passes theautomated style checks.
how they are solving the problem in a clear and encompassing way.
in the PR.
CHANGELOG.md.Runbook for Firecracker API changes.
integration tests.
TODO.rust-vmm.