[IOMMU] Provide invalidation hint to IOMMU page selective PASID-based IOTLB invalidation

Bug #1878523 reported by quanxian
This bug affects 1 person
Affects Status Importance Assigned to Milestone

Bug Description

Invalidation Hint (IH) can be provided for page-selective-within-PASID invalidations, the Invalidation Hint specifies if the first-level and nested mappings cached in the paging-structure-caches that controls the specified address/mask range needs to be invalidated or not. For software usages that update only the leaf PTEs, the first-level and nested mappings in the paging-structure-caches can be preserved by specifying the Invalidation Hint field value of 1.

However, currently our SVM code hardcode IH=0. which is less optimal. For vSVM, we have already added a generic flag (IOMMU_INV_ADDR_FLAG_LEAF) to indicate passdown cache invalidate API is for leaf PTE only. So as long as native SVM is fixed, vSVM could set the IH w/o code change.

SW needs to obtain statistics of non-leaf paging structure to provide IH bit.

static void intel_flush_svm_range(struct intel_svm *svm, unsigned long address,
unsigned long pages, int ih, int gl)

{ struct intel_svm_dev *sdev; rcu_read_lock(); list_for_each_entry_rcu(sdev, &svm->devs, list) intel_flush_svm_range_dev(svm, sdev, address, pages, ih, gl); rcu_read_unlock(); }
/* Pages have been freed at this point */
static void intel_invalidate_range(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start, unsigned long end)

{ struct intel_svm *svm = container_of(mn, struct intel_svm, notifier); intel_flush_svm_range(svm, start, (end - start + PAGE_SIZE - 1) >> VTD_PAGE_SHIFT, 0, 0); }

Target Kernel: TBD
Target Release: 23.10

quanxian (quanxian-wang)
description: updated
tags: added: intel-kernel-21.04
removed: intel-kernel-20.10
quanxian (quanxian-wang)
description: updated
quanxian (quanxian-wang)
description: updated
tags: added: intel-kernel-22.04
removed: intel-kernel-21.04
tags: added: intel-kernel-22.10
removed: intel-kernel-22.04
description: updated
quanxian (quanxian-wang)
description: updated
tags: added: intel-kernel-23.04
removed: intel-kernel-22.10
description: updated
tags: added: intel-kernel-23.10
removed: intel-kernel-23.04
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