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Add a tunable to disable migration of MSI-X interrupts.
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Authored by jhb on Jun 23 2016, 9:06 PM.

Details

Summary

Add a tunable to disable migration of MSI-X interrupts.

The new 'machdep.disable_msix_migration' tunable can be set to 1 to
disable migration of MSI-X interrupts.

Xen versions prior to 4.6.0 do not properly handle updates to MSI-X
table entries after the initial write. In particular, the operation
to unmask a table entry after updating it during migration is not
propagated to the "real" table for passthrough devices causing the
interrupt to remain masked. At least some systems in EC2 are
affected by this bug when using SRIOV. The tunable can be set in
loader.conf as a workaround

Submitted by: Jeremiah Lott <jlott@averesystems.com> (original patch)

Test Plan
  • Booted on a regular x86 box and saw no regressions with the tunable left off.

Diff Detail

Repository
rS FreeBSD src repository - subversion
Lint
Lint OK
Unit
No Unit Test Coverage
Build Status
Buildable 4325
Build 4370: arc lint + arc unit

Event Timeline

jhb retitled this revision from to Add a tunable to disable migration of MSI-X interrupts..
jhb updated this object.
jhb edited the test plan for this revision. (Show Details)
jhb added a reviewer: cperciva.
This revision was automatically updated to reflect the committed changes.