From add80ba59a85aca4c5e2619dee95557d2ec14169 Mon Sep 17 00:00:00 2001 From: eperezma Date: Mon, 11 Jan 2021 14:36:14 -0500 Subject: intel_iommu: Skip page walking on device iotlb invalidations MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: eperezma Message-id: <20210111143615.303645-5-eperezma@redhat.com> Patchwork-id: 100572 O-Subject: [RHEL-AV-8.4.0 qemu-kvm PATCH 4/5] intel_iommu: Skip page walking on device iotlb invalidations Bugzilla: 1845758 RH-Acked-by: Xiao Wang RH-Acked-by: David Hildenbrand RH-Acked-by: Peter Xu Although they didn't reach the notifier because of the filtering in memory_region_notify_iommu_one, the vt-d was still splitting huge memory invalidations in chunks. Skipping it. This improves performance in case of netperf with vhost-net: * TCP_STREAM: From 1923.6Mbit/s to 2175.13Mbit/s (13%) * TCP_RR: From 8464.73 trans/s to 8932.703333 trans/s (5.5%) * UDP_RR: From 8562.08 trans/s to 9005.62/s (5.1%) * UDP_STREAM: No change observed (insignificant 0.1% improvement) Signed-off-by: Eugenio Pérez Acked-by: Jason Wang Message-Id: <20201116165506.31315-5-eperezma@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin (cherry picked from commit f7701e2c7983b680790af47117577b285b6a1aed) Signed-off-by: Eugenio Pérez Signed-off-by: Danilo C. L. de Paula --- hw/i386/intel_iommu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index edc3090f91..0cc71e4057 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -1478,6 +1478,10 @@ static int vtd_sync_shadow_page_table(VTDAddressSpace *vtd_as) VTDContextEntry ce; IOMMUNotifier *n; + if (!(vtd_as->iommu.iommu_notify_flags & IOMMU_NOTIFIER_IOTLB_EVENTS)) { + return 0; + } + ret = vtd_dev_to_context_entry(vtd_as->iommu_state, pci_bus_num(vtd_as->bus), vtd_as->devfn, &ce); -- 2.18.4