vmm: fix UFFDIO_WAKE and UFFD_FEATURE_MISSING_HUGETLBFS - #8016
Merged
Merged
Conversation
UFFDIO_WAKE was 0x4010_aa02 (_IOW) but should be 0x8010_aa02, causing every wake call to silently fail with -EINVAL. UFFD_FEATURE_MISSING_HUGETLBFS was (1<<6) but should be (1<<4), colliding with UFFD_FEATURE_EVENT_UNMAP. Signed-off-by: Zhiheng Tao <[email protected]>
phip1611
approved these changes
Apr 14, 2026
phip1611
left a comment
Member
There was a problem hiding this comment.
I verified it and seems about right - thanks for your contribution!
| pub const UFFD_API: u64 = 0xAA; | ||
| pub const UFFDIO_REGISTER_MODE_MISSING: u64 = 1; | ||
| pub const UFFD_EVENT_PAGEFAULT: u8 = 0x12; | ||
| pub const UFFD_FEATURE_MISSING_HUGETLBFS: u64 = 1 << 4; |
Member
There was a problem hiding this comment.
yup. correct.
source: https://elixir.bootlin.com/linux/v7.0/source/include/uapi/linux/userfaultfd.h#L238
| pub const UFFDIO_REGISTER: u64 = 0xc020_aa00; // _IOWR(0xAA, 0x00, struct uffdio_register) | ||
| pub const UFFDIO_COPY: u64 = 0xc028_aa03; // _IOWR(0xAA, 0x03, struct uffdio_copy) | ||
| pub const UFFDIO_WAKE: u64 = 0x4010_aa02; // _IOW(0xAA, 0x02, struct uffdio_range) | ||
| pub const UFFDIO_WAKE: u64 = 0x8010_aa02; // _IOR(0xAA, 0x02, struct uffdio_range) |
Member
There was a problem hiding this comment.
Also seems about right - I verified it! thanks!
rbradford
approved these changes
Apr 14, 2026
rbradford
enabled auto-merge
April 14, 2026 06:55
github-merge-queue
Bot
removed this pull request from the merge queue due to failed status checks
Apr 14, 2026
This comment was marked as outdated.
This comment was marked as outdated.
github-merge-queue
Bot
removed this pull request from the merge queue due to failed status checks
Apr 14, 2026
Member
|
@rbradford I think I have a patch for that failure commit 29ed4622ac4a10ce05b5c5cbe6c687fb5d0f41b2
Author: Philipp Schuster <[email protected]>
Date: Tue Apr 14 10:30:26 2026 +0200
tests: make VFIO memory hotplug more robust
After memory hotplug, it may happen that it takes a few seconds until a
VFIO device is available again (IOMMU/DMA mappings need update).
On-behalf-of: SAP [email protected]
Signed-off-by: Philipp Schuster <[email protected]>
diff --git a/cloud-hypervisor/tests/integration.rs b/cloud-hypervisor/tests/integration.rs
index 82c24a4f8..1c4a49478 100644
--- a/cloud-hypervisor/tests/integration.rs
+++ b/cloud-hypervisor/tests/integration.rs
@@ -8385,8 +8385,10 @@ mod vfio {
}));
assert!(guest.get_total_memory().unwrap_or_default() > 5_760_000);
- // Check the VFIO device works when RAM is increased to 6GiB
- assert!(guest.check_nvidia_gpu());
+ // Check the VFIO device works when RAM is increased to 6GiB.
+ // After guest memory hotplug, the VMM must refresh VFIO/iommufd DMA
+ // mappings for the passthrough GPU.
+ assert!(wait_until(Duration::from_secs(10), || guest.check_nvidia_gpu()));
});
let _ = child.kill();WDYT? |
shayonj
approved these changes
Apr 14, 2026
shayonj
left a comment
Contributor
There was a problem hiding this comment.
Good catch, thank you for the fix! Verified here as well - https://github.com/torvalds/linux/blob/d60bc140158342716e13ff0f8aa65642f43ba053/include/uapi/linux/userfaultfd.h#L21
On the side, I will see if a compile-time ioctl encoding validation possible to have these caught early in CI
Contributor
|
Proposed #8019. We can see the CI catching this now for future proofing. Can rebase once this PR lands |
This file contains hidden or 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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
4 participants
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.
UFFDIO_WAKE was 0x4010_aa02 (_IOW) but should be 0x8010_aa02, causing every wake call to silently fail with -EINVAL.
UFFD_FEATURE_MISSING_HUGETLBFS was (1<<6) but should be (1<<4), colliding with UFFD_FEATURE_EVENT_UNMAP.
This PR fix these const values.