Messages in this thread | | | Date | Thu, 9 Mar 2023 22:02:21 +0800 | Subject | Re: [PATCH 00/12] iommufd: Add nesting infrastructure | From | Baolu Lu <> |
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On 2023/3/9 16:08, Yi Liu wrote: > Nested translation is a hardware feature that is supported by many modern > IOMMU hardwares. It has two stages (stage-1, stage-2) address translation > to get access to the physical address. stage-1 translation table is owned > by userspace (e.g. by a guest OS), while stage-2 is owned by kernel. Changes > to stage-1 translation table should be followed by an IOTLB invalidation.
The last sentence is not always true. If any entry of the stage-1 translation table is changed from non-present to present, the IOTLB has no chance to cache it yet. Hence there's no need for invalidation.
Best regards, baolu
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