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Date: Wed, 24 Jan 2024 21:09:22 -0800
From: Nicolin Chen <nicolinc@nvidia.com>
To: "zhangzekun (A)" <zhangzekun11@huawei.com>
CC: Jason Gunthorpe <jgg@nvidia.com>, "will@kernel.org" <will@kernel.org>,
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Subject: Re: [PATCH 1/3] iommu/io-pgtable-arm: Add nents_per_pgtable in
 struct io_pgtable_cfg
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On Wed, Jan 24, 2024 at 02:20:14PM +0800, zhangzekun (A) wrote:
> Also, it seems to me that SVA use cases and, say, DMA API cases are
> somewhat different where we may be willing to wait longer for DMA API.
 
> Hmm, the lockup that my patch fixed was for an SVA case that
> doesn't seem to involve DMA API:
> https://lore.kernel.org/linux-iommu/20230901203904.4073-1-nicolinc@nvidia.com/
> 
> And the other lockup fix for a non-SVA case from Zhang doesn't
> seem to involve DMA API either:
> https://lore.kernel.org/linux-iommu/e74ea905-d107-4202-97ca-c2c509e7aa1e@huawei.com/
> 
> 
> Hi, Nicolin
> 
> These patches do involve DMA APIs, because it modifies arm_smmu_tlb_inv_walk() which will be called when unmapping dma address space.
> 
> iommu_dma_unmap_page
>    __iommu_dma_unmap
>        __iommu_unmap
>            arm_smmu_unmap_pages
>                arm_lpae_unmap_pages
>                    io_pgtable_tlb_flush_walk
>                        arm_smmu_tlb_inv_walk
> 

Oh, thanks for clarifying. I was just looking at your trace log
there, but overlooked other places.