Hi Will, 在 2021/3/29 22:45, Will Deacon 写道:
On Sat, Mar 27, 2021 at 02:23:10PM +0800, chenxiang wrote:
From: Xiang Chen <chenxiang66@hisilicon.com>
Currently it will send a iotlb sync at end of iommu unmap even if iotlb_gather is not valid (iotlb_gather->pgsize = 0). Actually it is not necessary, so add a check to avoid invalid iotlb sync.
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com> --- include/linux/iommu.h | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 9ca6e6b..6afa61b 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -529,6 +529,9 @@ static inline void iommu_flush_iotlb_all(struct iommu_domain *domain) static inline void iommu_iotlb_sync(struct iommu_domain *domain, struct iommu_iotlb_gather *iotlb_gather) { + if (!iotlb_gather->pgsize) + return; In which circumstances does this occur?
Will
When iommu_unmap, it initializes iotlb_gather (then iotlb_gather->pgsize = 0). If the unmap size = ARM_LPAE_BLOCK_SIZE(lvl) && iopte_leaf(), it will fill the iotlb_gather (set iotlb_gather->pgsize = granule); but if the unmap size = ARM_LPAE_BLOCK_SIZE(lvl) && !iopte_leaf() (tlb flush walk situation), iotlb_gather is not filled (iotlb_gather->pgsize = 0), it will still send iommu_iotlb_sync(domain, &iotlb_gather) which is actually invalid iotlb sync at last.
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