[RFC v5 3/3] intel_iommu: Do not notify regular iotlb to device-iotlb notifiers

["Eugenio Pérez" <eperezma@redhat.com>]

This improves performance in case of netperf with vhost-net:
* TCP_STREAM: From 1374.81Mbit/s to 1845Mbit/s (37%)
* TCP_RR: From 6559.36 trans/s to 7916.29/s (21%)
* UDP_RR: From 6705.39 trans/s to 8199.39/s (22%)
* UDP_STREAM: No change observed (not significant 0.1% improvement)

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/i386/intel_iommu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 2ad6b9d796..d539a9f281 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -1959,6 +1959,12 @@ static void vtd_iotlb_domain_invalidate(IntelIOMMUState *s, uint16_t domain_id)
     vtd_iommu_unlock(s);
 
     QLIST_FOREACH(vtd_as, &s->vtd_as_with_notifiers, next) {
+        if (vtd_as->iommu.iommu_notify_flags & IOMMU_NOTIFIER_DEVIOTLB) {
+            /* If IOMMU memory region is DEVICE IOTLB type, it does not make
+             * sense to send regular IOMMU notifications. */
+            continue;
+        }
+
         if (!vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus),
                                       vtd_as->devfn, &ce) &&
             domain_id == vtd_get_domain_id(s, &ce)) {
-- 
2.18.1