On 16/06/2021 11:04, Nadav Amit wrote:
- if (iommu->cap & (1UL << IOMMU_CAP_NPCACHE))
+ if (iommu->cap & (1UL << IOMMU_CAP_NPCACHE)) {
+ if (!amd_iommu_unmap_flush)
+ pr_warn("IOMMU batching is disabled due to
virtualization");
This is missing
From: Nadav Amit
Do not use flush-queue on virtualized environments, where the NpCache
capability of the IOMMU is set. This is required to reduce
virtualization overheads.
This change follows a similar change to Intel's VT-d and a detailed
explanation as for the rationale is described in commit
