Reset dirty log on full snapshot path

[Msknsngla]

Changes

• Added the get_dirty_bitmap on the full snapshot path

Reason

• The full snapshot path doesn’t call Vmm:get_dirty_bitmap thus doesn’t call KVM_GET_DIRTY_LOG which doesn’t reset dirty pages.

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

• If a specific issue led to this PR, this PR closes the issue.
• The description of changes is clear and encompassing.
• Any required documentation changes (code and docs) are included in this PR.
• API changes follow the Runbook for Firecracker API changes.
• User-facing changes are mentioned in CHANGELOG.md.
• All added/changed functionality is tested.
• New TODOs link to an issue.
• Commits meet contribution quality standards.

---

• This functionality cannot be added in rust-vmm.

[Msknsngla]

Created a draft PR to check of the logic is correct, if so will create the PR with some refactoring.

[JonathanWoollett-Light]

Unless I'm misunderstanding (@pb8o please let me know).

This replicates the behavior of diff snapshots, it won't output the non-dirty pages.

It should output all pages when taking a full snapshot e.g.

Suggested change

	SnapshotType::Full => {
	let dirty_bitmap = vmm.get_dirty_bitmap().map_err(DirtyBitmap)?;
	vmm.guest_memory()
	.dump_dirty(&mut file, &dirty_bitmap)
	.map_err(Memory)
	}
	SnapshotType::Full => {
	// Reset dirty pages.
	let _ = vmm.get_dirty_bitmap().map_err(DirtyBitmap)?;
	// Dump all pages.
	vmm.guest_memory()
	.dump(&mut file)
	.map_err(Memory)
	}

See https://github.com/firecracker-microvm/firecracker/blob/main/src/vmm/src/vstate/memory.rs#L271:L337

[JonathanWoollett-Light]

Replaced by #4385