IOMMU support episode II #393
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
broskoTT
approved these changes
Dec 11, 2024
This should just work provided the IOMMU is enabled. It will fail if IOMMU is disabled or in passthrough mode and there are no hugepages available. I suppose a caveat here is this hasn't been extensively tested. |
broskoTT
pushed a commit
that referenced
this pull request
Dec 13, 2024
Reverts commit 3210bd9 from #393. ### Issue Metal CI failure tracked in tenstorrent/tt-metal#15675 ### Description The reverted commit removed logic that allowed applications to request more hugepages than available to UMD. Previously, UMD would issue a warning in such cases. However, this created a potential safety issue since applications had no visibility into partial hugepage allocation (e.g., requesting 4 pages but receiving only 2). This situation could lead to: - Host software segfaults when accessing unmapped pages - More critically, device software could potentially corrupt host physical address space by writing to nonexistent pages While the original change (making excessive hugepage requests a fatal error) improved safety, particularly in conjunction with IOMMU enablement, it caused failures in Metal CI tests that (possibly unintentionally?) request more hugepages than available. This revert is a temporary measure until the Metal CI tests can be updated. ### List of the changes * Revert 3210bd9 * Update comment documentation ### Testing CI ### API Changes There are no API changes in this PR.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Issue
#370
Description
Adds IOMMU support for Blackhole in a way that should be transparent to the application.
List of the changes
Testing
Manual testing was performed for both IOMMU on and IOMMU off cases using the newly-added sysmem tests for Blackhole.
With IOMMU on:
With IOMMU in passthrough:
API Changes
There are no API changes in this PR.