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SubjectRe: [PATCH v4 6/7] iommu/mediatek: Gather iova in iommu_unmap to achieve tlb sync once
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On 2021-01-07 12:29, Yong Wu wrote:
> In current iommu_unmap, this code is:
>
> iommu_iotlb_gather_init(&iotlb_gather);
> ret = __iommu_unmap(domain, iova, size, &iotlb_gather);
> iommu_iotlb_sync(domain, &iotlb_gather);
>
> We could gather the whole iova range in __iommu_unmap, and then do tlb
> synchronization in the iommu_iotlb_sync.
>
> This patch implement this, Gather the range in mtk_iommu_unmap.
> then iommu_iotlb_sync call tlb synchronization for the gathered iova range.
> we don't call iommu_iotlb_gather_add_page since our tlb synchronization
> could be regardless of granule size.
>
> In this way, gather->start is impossible ULONG_MAX, remove the checking.
>
> This patch aims to do tlb synchronization *once* in the iommu_unmap.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
> drivers/iommu/mtk_iommu.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 66a00a2cb445..d3b8a1649093 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -430,7 +430,12 @@ static size_t mtk_iommu_unmap(struct iommu_domain *domain,
> struct iommu_iotlb_gather *gather)
> {
> struct mtk_iommu_domain *dom = to_mtk_domain(domain);
> + unsigned long end = iova + size - 1;
>
> + if (gather->start > iova)
> + gather->start = iova;
> + if (gather->end < end)
> + gather->end = end;
> return dom->iop->unmap(dom->iop, iova, size, gather);
> }
>
> @@ -445,9 +450,6 @@ static void mtk_iommu_iotlb_sync(struct iommu_domain *domain,
> struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
> size_t length = gather->end - gather->start + 1;
>
> - if (gather->start == ULONG_MAX)
> - return;
> -
> mtk_iommu_tlb_flush_range_sync(gather->start, length, gather->pgsize,
> data);
> }
>

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