This series based on "Share sva" patch-set[1], aims to remove superfluous IOMMU IOTLB invalidations in VT-d driver. In the current VT-d driver, IOMMU IOTLB invalidation commands and device-TLB commands are performed per device, which leads to superfluous IOTLB invalidations. For example, if there are four devices behind a IOMMU are attached to one sva domain (which could be a common case in virtualization scenarios where one virtual IOMMU working for all the virtual devices), four IOTLB invalidation commands and four device-IOTLB invalidation commands will be issued. However, only one IOTLB invalidation command and four device-IOTLB invalidation commands are necessary. Superfluous IOMMU IOTLB invalidations impact run-time performance. Although the goal could be built straight-forwardly in the current VT-d driver, some refactoring works are considered necessary before landing the one solving the problem of redundant IOTLB invalidations: 1) VT-d driver uses different structures to keep attached device info. For default domain, it uses struct dev_pasids_info and some related fields of struct dmar_domain. For sva domain, it uses struct intel_svm and struct intel_svm_dev. The reason of it is because previously the sva domain is not shared among devices behind different IOMMUs and therefore dmar_domain and its fields cannot be used globally to keep all attached device info. After the patch-set[1] gets acceptance, sva domain is global to the attached devices. Thus, retiring struct intel_svm/intel_svm_dev is the main refactoring work of this patch-set. 2) Most logic of intel_svm_set_dev_pasid() can be covered by intel_iommu_set_dev_pasid(). Refactoring both intel_svm_set_dev_pasid() and intel_iommu_set_dev_pasid() and let the former call the latter for set_dev_pasid operation to avoid duplicating code. 3) Last but not least, struct mmu_notifier is proposed to iommu_domain. This is a change to IOMMU core, which helps to centralize info required by sva to sva domain and therefore can help cleanup the code in IOMMU drivers. This patchset is on github per-iommu_IOTLB_invalidation branch[2]. [1]: https://lore.kernel.org/linux-iommu/20231017004802.109618-1-tina.zhang@xxxxxxxxx/ [2]: https://github.com/TinaZhangZW/linux/tree/per-iommu_IOTLB_invalidation Tina Zhang (12): iommu/vt-d: Retire the treatment for revoking PASIDs with pending pgfaults iommu/vt-d: Remove initialization for dynamically heap-allocated rcu_head iommu/vt-d: Retire intel_svm_bind_mm() iommu/vt-d: Make dev_to_intel_iommu() helper global iommu/vt-d: Retire struct intel_svm_dev iommu: Add mmu_notifier to sva domain iommu/vt-d: Retire struct intel_svm iommu/vt-d: Use RCU for dev_pasids list updates in set/remove_dev_pasid() iommu/vt-d: Refactor intel_iommu_set_dev_pasid() iommu/vt-d: Refactor intel_iommu_remove_dev_pasid() iommu/vt-d: Use intel_iommu_set_dev_pasid() for sva domain iommu/vt-d: Remove superfluous IOMMU IOTLB invalidations drivers/iommu/intel/iommu.c | 91 +++++++++---- drivers/iommu/intel/iommu.h | 30 ++--- drivers/iommu/intel/svm.c | 261 ++++++++---------------------------- include/linux/iommu.h | 2 + 4 files changed, 128 insertions(+), 256 deletions(-) -- 2.39.3
