iommu/vt-d: Use rbtree to track iommu probed devices
Use a red-black tree(rbtree) to track devices probed by the driver's probe_device callback. These devices need to be looked up quickly by a source ID when the hardware reports a fault, either recoverable or unrecoverable. Fault reporting paths are critical. Searching a list in this scenario is inefficient, with an algorithm complexity of O(n). An rbtree is a self-balancing binary search tree, offering an average search time complexity of O(log(n)). This significant performance improvement makes rbtrees a better choice. Furthermore, rbtrees are implemented on a per-iommu basis, eliminating the need for global searches and further enhancing efficiency in critical fault paths. The rbtree is protected by a spin lock with interrupts disabled to ensure thread-safe access even within interrupt contexts. Co-developed-by: Huang Jiaqing <jiaqing.huang@intel.com> Signed-off-by: Huang Jiaqing <jiaqing.huang@intel.com> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/20240220065939.121116-2-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
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