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…rting Allow driver writes (including byte/word sub-field accesses) to both writable virtio-balloon configuration fields (`actual` and `poison_val`) while continuing to reject writes to read-only or out-of-bounds offsets. Track negotiated `BalloonFeature` flags in `Balloon::activate` (and clear `driver_feature`, `actual`, and `poison_val` in `Balloon::reset`). Per Virtio v1.4 Sec 5.5.6.6, when `VIRTIO_BALLOON_F_PAGE_POISON` is negotiated, the device must not modify reported free pages to a value other than `poison_val`. Skip `madvise(MADV_DONTNEED)` in `free_reporting` when `PAGE_POISON` is negotiated with a non-zero `poison_val`, while continuing to reclaim pages when `PAGE_POISON` is not negotiated or `poison_val == 0`. Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Coverage Report for CI Build 42955367146Coverage increased (+0.9%) to 44.524%Details
Uncovered Changes
Coverage RegressionsNo coverage regressions found. Coverage Stats
💛 - Coveralls |
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Summary
BalloonConfig::poison_valas well asBalloonConfig::actual, while continuing to reject writes to read-only fields (num_pages,free_page_hint_cmd_id), cross-field boundaries, invalid access widths, and out-of-bounds offsets.BalloonFeaturebits onBalloonduringVirtioMio::activate, and cleardriver_feature,actual, andpoison_valonVirtioMio::reset.VIRTIO_BALLOON_F_PAGE_POISONis negotiated: skipmadvise(..., MADV_DONTNEED)whenpoison_val != 0so reported free pages are not overwritten with zeroes, while continuing to reclaim reported pages whenPAGE_POISONis not negotiated orpoison_val == 0.alioth/src/virtio/dev/balloon_test.rscoveringBalloonConfigMmioread/write validation,free_reportingunder allPAGE_POISON/poison_valcombinations, and devicereset+ re-activation on both 4 KiB and 16 KiB page hosts.Verification
cargo +nightly fmt --checkcargo test -p alioth virtio::dev::ballooncargo clippy --all-targets -- -D warningscargo clippy --all-targets --target x86_64-unknown-linux-gnu -- -D warnings