From 2fd6f6c8cb3562476c3372f36f22fd8ab81b371d Mon Sep 17 00:00:00 2001 From: Jacob Pan Date: Thu, 16 Feb 2023 21:08:14 +0800 Subject: [PATCH] iommu/vt-d: Avoid superfluous IOTLB tracking in lazy mode commit 16a75bbe480c3598b3af57a2504ea89b1e32c3ac upstream. Intel IOMMU driver implements IOTLB flush queue with domain selective or PASID selective invalidations. In this case there's no need to track IOVA page range and sync IOTLBs, which may cause significant performance hit. This patch adds a check to avoid IOVA gather page and IOTLB sync for the lazy path. The performance difference on Sapphire Rapids 100Gb NIC is improved by the following (as measured by iperf send): w/o this fix~48 Gbits/s. with this fix ~54 Gbits/s Cc: Fixes: 2a2b8eaa5b25 ("iommu: Handle freelists when using deferred flushing in iommu drivers") Reviewed-by: Robin Murphy Reviewed-by: Kevin Tian Tested-by: Sanjay Kumar Signed-off-by: Sanjay Kumar Signed-off-by: Jacob Pan Link: https://lore.kernel.org/r/20230209175330.1783556-1-jacob.jun.pan@linux.intel.com Signed-off-by: Lu Baolu Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/intel/iommu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 9666391240928..29538471c528e 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -5140,7 +5140,12 @@ static size_t intel_iommu_unmap(struct iommu_domain *domain, if (dmar_domain->max_addr == iova + size) dmar_domain->max_addr = iova; - iommu_iotlb_gather_add_page(domain, gather, iova, size); + /* + * We do not use page-selective IOTLB invalidation in flush queue, + * so there is no need to track page and sync iotlb. + */ + if (!iommu_iotlb_gather_queued(gather)) + iommu_iotlb_gather_add_page(domain, gather, iova, size); return size; }