Re: [PATCH] iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()

[Will Deacon]

On Thu, 16 Jul 2026 22:16:22 +0800, Guanghui Feng wrote:
> need_sync is a per-IOMMU flag shared by all domains and devices behind
> that IOMMU. It is set whenever a command is queued with sync == true and
> cleared when a completion-wait (CWAIT) command is queued. However, a
> cleared need_sync only means that a covering CWAIT has been queued, not
> that all previously queued commands have actually completed in hardware.
> 
> iommu_completion_wait() read need_sync locklessly and returned early
> when it was false. This breaks the "block until all previously queued
> commands have completed" contract in a multi-CPU scenario:
> 
> [...]

Applied to iommu (fixes), thanks!

[1/1] iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()
      https://git.kernel.org/iommu/c/1e75a8255f11

Cheers,
-- 
Will

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