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SubjectRe: [PATCH 2/5] iommu/vt-d: Remove WO permissions on second-level paging entries
On Thu, Feb 25, 2021 at 02:26:51PM +0800, Lu Baolu wrote:
> When the first level page table is used for IOVA translation, it only
> supports Read-Only and Read-Write permissions. The Write-Only permission
> is not supported as the PRESENT bit (implying Read permission) should
> always set. When using second level, we still give separate permissions
> that allows WriteOnly which seems inconsistent and awkward. There is no
> use case we can think off, hence remove that configuration to make it
> consistent.

No use-case for WriteOnly mappings? How about DMA_FROM_DEVICE mappings?

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