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Blame SOURCES/kvm-virtio-scsi-Configure-all-host-notifiers-in-a-single.patch

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From 5e7855d3c9d5a59d2c0ac05444428b058ca9abb8 Mon Sep 17 00:00:00 2001
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From: Greg Kurz <groug@kaod.org>
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Date: Wed, 26 May 2021 09:03:54 -0400
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Subject: [PATCH 14/15] virtio-scsi: Configure all host notifiers in a single
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 MR transaction
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RH-Author: Miroslav Rezanina <mrezanin@redhat.com>
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RH-MergeRequest: 5: Synchronize RHEL-AV 8.5 release 18 to RHEL 9 Beta
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RH-Commit: [11/12] f3c785c4b63aeb3a7b153f2fc17e86c983f98c23 (mrezanin/centos-src-qemu-kvm)
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RH-Bugzilla: 1957194
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RH-Acked-by: Danilo Cesar Lemes de Paula <ddepaula@redhat.com>
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: Greg Kurz <gkurz@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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This allows the virtio-scsi-pci device to batch the setup of all its
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host notifiers. This significantly improves boot time of VMs with a
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high number of vCPUs, e.g. from 6m5.563s down to 1m2.884s for a
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pseries machine with 384 vCPUs.
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Note that memory_region_transaction_commit() must be called before
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virtio_bus_cleanup_host_notifier() because the latter might close
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ioeventfds that the transaction still assumes to be around when it
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commits.
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Signed-off-by: Greg Kurz <groug@kaod.org>
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Message-Id: <20210407143501.244343-5-groug@kaod.org>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit c4f5dcc4360a02085a633fd7a90b7ac395ca1ba4)
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Signed-off-by: Greg Kurz <gkurz@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/scsi/virtio-scsi-dataplane.c | 16 ++++++++++++++++
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 1 file changed, 16 insertions(+)
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diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
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index b2cb3d9dcc..28e003250a 100644
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--- a/hw/scsi/virtio-scsi-dataplane.c
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+++ b/hw/scsi/virtio-scsi-dataplane.c
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@@ -152,6 +152,8 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
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         goto fail_guest_notifiers;
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     }
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+    memory_region_transaction_begin();
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+
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     rc = virtio_scsi_set_host_notifier(s, vs->ctrl_vq, 0);
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     if (rc != 0) {
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         goto fail_host_notifiers;
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@@ -173,6 +175,8 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
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         vq_init_count++;
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     }
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+    memory_region_transaction_commit();
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+
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     aio_context_acquire(s->ctx);
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     virtio_queue_aio_set_host_notifier_handler(vs->ctrl_vq, s->ctx,
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                                             virtio_scsi_data_plane_handle_ctrl);
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@@ -192,6 +196,11 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
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 fail_host_notifiers:
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     for (i = 0; i < vq_init_count; i++) {
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         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
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+    }
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+
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+    memory_region_transaction_commit();
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+
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+    for (i = 0; i < vq_init_count; i++) {
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         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
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     }
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     k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
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@@ -229,8 +238,15 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
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     blk_drain_all(); /* ensure there are no in-flight requests */
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+    memory_region_transaction_begin();
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+
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     for (i = 0; i < vs->conf.num_queues + 2; i++) {
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         virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
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+    }
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+
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+    memory_region_transaction_commit();
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+
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+    for (i = 0; i < vs->conf.num_queues + 2; i++) {
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         virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
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     }
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-- 
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2.27.0
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