From 16a75bbe480c3598b3af57a2504ea89b1e32c3ac 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 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 --- 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 9107fac8c3753..547977d535c56 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -4348,7 +4348,12 @@ 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; } -- 2.30.2