rust-vmm/vhost

Inflight I/O: Fix the memory layout of queue region header

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#356 opened on Apr 28, 2026

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good first issue

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Description

From https://github.com/rust-vmm/vhost/pull/88:

As defined in the vhost-user protocol[1], the last field of queue region header should be a zero-sized array. However, current implementation uses u64, which will cause a wrong inflight I/O memfd memory layout.

That PR was never merged, because we should fix the issue using vmm_sys_util::fam.

Contributor guide

Research direction
Investigate the vhost user protocol specification for the queue region header, then implement the fix using vmm sys util::fam to change the last field from u64 to a zero sized array.
Tech stack
rust
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Rustvhost protocolflexible array members
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40