[Feature Request] Transparent Huge Pages Support

[JamesC1305]

(Derived from #5495)

Feature Request

We would like to be able to enable transparent huge pages for Firecracker VMs. This would allow huge pages to be used without any explicit reservation via hugetlbfs.

Describe the desired solution

A new config option that, when enabled, uses THP.

Describe possible alternatives

Firecracker currently supports huge pages via hugetlbfs. The user has to reserve huge pages before beforehand. A config option then exists to enable the use of them.

Additional context

We are interested in THP, but our concerns had previously been around the incompatibility between UFFD and THP. Ideally, we would like an implementation that would allow THP to be used in combination with UFFD, although that may require upstream kernel changes. See comments on #5495.

Checks

• Have you searched the Firecracker Issues database for similar requests?
• Have you read all the existing relevant Firecracker documentation?
• Have you read and understood Firecracker's core tenets?