aws: properly support instance types with > 255 cpu cores
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux-aws (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Xenial |
Fix Released
|
Medium
|
Unassigned | ||
Bionic |
Fix Released
|
Medium
|
Unassigned | ||
Focal |
Fix Released
|
Medium
|
Unassigned | ||
Groovy |
Fix Released
|
Medium
|
Andrea Righi |
Bug Description
[Impact]
To properly support instance types in AWS with > 255 cores we need to make sure that commit c40aaaac1018ff1
[Test Case]
Tests performed by AWS.
[Fix]
Apply/backport commit c40aaaac1018ff1
For groovy it's a clean cherry pick.
For Focal/Bionic the backport activity is to simply rename the patched file.
Only Xenial requires a little more backporting activity, in particular we need to change the condition in free_iommu() checking if iommu->iommu_dev is defined (instead of checking for iommu->iommu.ops, that is not available in the 4.4 kernel).
[Regression potential]
This change allows to use DMAR units that were not used before (for interrupt remapping). Theoretically this should provide a performance improvement, but we should keep an eye about potential performance regressions of drivers that are using IOMMU, in case they're using this new behavior incorrectly.
Moreover, the Xenial backport required an adjustment in free_iommu() to check when we need to call iommu_device_
CVE References
Changed in linux-aws (Ubuntu Bionic): | |
importance: | Undecided → Medium |
importance: | Medium → High |
Changed in linux-aws (Ubuntu Focal): | |
importance: | Undecided → High |
Changed in linux-aws (Ubuntu Bionic): | |
importance: | High → Medium |
Changed in linux-aws (Ubuntu Focal): | |
importance: | High → Medium |
Changed in linux-aws (Ubuntu Xenial): | |
importance: | Undecided → Medium |
status: | New → In Progress |
Changed in linux-aws (Ubuntu Focal): | |
status: | New → In Progress |
Changed in linux-aws (Ubuntu Bionic): | |
status: | New → In Progress |
Changed in linux-aws (Ubuntu Groovy): | |
importance: | Undecided → Medium |
status: | New → In Progress |
assignee: | nobody → Andrea Righi (arighi) |
description: | updated |
no longer affects: | linux-aws (Ubuntu Hirsute) |
Changed in linux-aws (Ubuntu Xenial): | |
status: | In Progress → Fix Committed |
Changed in linux-aws (Ubuntu Bionic): | |
status: | In Progress → Fix Committed |
Changed in linux-aws (Ubuntu Focal): | |
status: | In Progress → Fix Committed |
Changed in linux-aws (Ubuntu Groovy): | |
status: | In Progress → Fix Committed |
Validation results. Proper number of vpus did show up in Bionic, Focal, Groovy, and Xenial-4.15. The Xenial 4.4 kernel only saw 256 vcpus.
ubuntu@ ip-172- 31-5-48: ~$ uname -r && nproc
4.4.0-1121-aws
144
ubuntu@ ip-172- 31-5-48: ~$ uname -r && nproc
4.4.0-1122-aws
256
ubuntu@ ip-172- 31-5-48: ~$ uname -r && nproc
4.15.0-1094-aws
448