Cloud Hypervisor used to crash when a VFIO DMA range crossed a mapping gap

A BAR can be backed by non-contiguous mmap areas, so a range that fits the BAR can still miss every individual mapping. ## Notes b1c796ff4471 (Leo Li, 2026-08-17). Reject VFIO DMA ranges not contained in one mmap area. A DMA range can fit a logical VFIO BAR while extending past one mmap-backed area. That used to trip an assert. The lookup now skips mappings that cannot cover the full range and returns an error if none can. Adds a regression test for a range that fits the BAR but crosses an unmapped gap. Assisted-by ChatGPT in the commit. Landed on main. Latest release remains v53.0. No GHSA. Not the cf598205 crate pin. Not virtio OOB, not 9336633a HTTP body limit.