Add snapsafety features to VMClock device #5564
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Codecov Report❌ Patch coverage is
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## main #5564 +/- ##
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+ Coverage 83.22% 83.24% +0.01%
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Files 277 277
Lines 29275 29312 +37
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+ Hits 24364 24400 +36
- Misses 4911 4912 +1
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mostly lgtm, just a few clarification on the doc
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Add support for vm_generation_counter and notifications. Keep this separately for now, as a patch to the VMClock bindings, since currently upstream bindings don't include it. We will recreate this for Linux headers once they are released, at which point we will need to drop the bindgen patch. 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]>
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]>
Mention support for VMClock and give pointers that required patches for snapshot safety support. Signed-off-by: Babis Chalios <[email protected]>
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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
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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.