Messages in this thread | | | From | Nadav Amit <> | Subject | Re: [PATCH 3/4] iommu/amd: Do not sync on page size changes | Date | Tue, 1 Jun 2021 16:39:54 +0000 |
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> On Jun 1, 2021, at 8:59 AM, Robin Murphy <robin.murphy@arm.com> wrote: > > On 2021-05-02 07:59, Nadav Amit wrote: >> From: Nadav Amit <namit@vmware.com> >> Some IOMMU architectures perform invalidations regardless of the page >> size. In such architectures there is no need to sync when the page size >> changes or to regard pgsize when making interim flush in >> iommu_iotlb_gather_add_page(). >> Add a "ignore_gather_pgsize" property for each IOMMU-ops to decide >> whether gather's pgsize is tracked and triggers a flush. > > I've objected before[1], and I'll readily object again ;) > > I still think it's very silly to add a bunch of indirection all over the place to make a helper function not do the main thing it's intended to help with. If you only need trivial address gathering then it's far simpler to just implement trivial address gathering. I suppose if you really want to you could factor out another helper to share the 5 lines of code which ended up in mtk-iommu (see commit f21ae3b10084).
Thanks, Robin.
I read your comments but I cannot fully understand the alternative that you propose, although I do understand your objection to the indirection “ignore_gather_pgsize”. Would it be ok if “ignore_gather_pgsize" was provided as an argument for iommu_iotlb_gather_add_page()?
In general, I can live without this patch. It probably would have negligent impact on performance anyhow.
Regards, Nadav
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