openhcl: fix lower vtl permissions guard drop order and new failures (#4205) - #4213
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Chris Oo (chris-oo) merged 1 commit intoAug 13, 2026
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…icrosoft#4205) Fix two bugs in lower vtl permissiosn guard. One is around drop ordering, where we must restore VTL protections to allocated pages before returning them to allocation pools, and the other is to handle partial failures on construction by rolling back protections.
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Steven Malis (smalis-msft)
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Aug 11, 2026
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Pull request overview
Fixes correctness issues in the OpenHCL lower_vtl_permissions_guard around (1) ensuring VTL protections are restored before pages are returned to allocation pools, and (2) improving behavior when lowering permissions fails partway through guard construction.
Changes:
- Track successfully-updated PFNs during
PagesAccessibleToLowerVtlconstruction to enable rollback on partial failures. - Reorder
LowerVtlDmaBufferfields so the VTL guard is dropped before the underlyingMemoryBlock.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
openhcl/lower_vtl_permissions_guard/src/lib.rs |
Tracks updated pages during guard construction to support rollback on partial failures. |
openhcl/lower_vtl_permissions_guard/src/device_dma.rs |
Reorders fields to ensure VTL protections are restored before freeing the DMA MemoryBlock. |
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Comment on lines
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| for pfn in pages { | ||
| vtl_protect | ||
| guard | ||
| .vtl_protect | ||
| .modify_vtl_page_setting(*pfn, hvdef::HV_MAP_GPA_PERMISSIONS_ALL) | ||
| .context("failed to update VTL protections on page")?; |
Chris Oo (chris-oo)
merged commit Aug 13, 2026
b85db1e
into
microsoft:release/1.8.2607
185 of 193 checks passed
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Fix two bugs in lower vtl permissiosn guard. One is around drop ordering, where we must restore VTL protections to allocated pages before returning them to allocation pools, and the other is to handle partial failures on construction by rolling back protections.
Clean cherry pick of (#4205).