Blame SOURCES/kvm-tap-set-vhostfd-passed-from-qemu-cli-to-non-blocking.patch

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From 689a30f211939282ce6de9d3597c0fc6ad674a6e Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Fri, 26 Jul 2019 11:29:51 +0100
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Subject: [PATCH 13/14] tap: set vhostfd passed from qemu cli to non-blocking
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RH-Author: Laszlo Ersek <lersek@redhat.com>
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Message-id: <20190726112951.11834-2-lersek@redhat.com>
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Patchwork-id: 89734
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O-Subject: [RHEL-8.1.0 qemu-kvm PATCH 1/1] tap: set vhostfd passed from qemu cli to non-blocking
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Bugzilla: 1732642
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RH-Acked-by: Xiao Wang <jasowang@redhat.com>
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RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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From: Brijesh Singh <brijesh.singh@amd.com>
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A guest boot hangs while probing the network interface when
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iommu_platform=on is used.
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The following qemu cli hangs without this patch:
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# $QEMU \
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  -netdev tap,fd=3,id=hostnet0,vhost=on,vhostfd=4 3<>/dev/tap67 4<>/dev/host-net \
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  -device virtio-net-pci,netdev=hostnet0,id=net0,iommu_platform=on,disable-legacy=on \
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  ...
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Commit: c471ad0e9bd46 (vhost_net: device IOTLB support) took care of
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setting vhostfd to non-blocking when QEMU opens /dev/host-net but if
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the fd is passed from qemu cli then we need to ensure that fd is set
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to non-blocking.
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Fixes: c471ad0e9bd46 ("vhost_net: device IOTLB support")
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Cc: qemu-stable@nongnu.org
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Cc: Michael S. Tsirkin <mst@redhat.com>
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Cc: Jason Wang <jasowang@redhat.com>
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Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
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Signed-off-by: Jason Wang <jasowang@redhat.com>
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(cherry picked from commit d542800d1edc62f63f8a29cfa6bdd1a9536ae11c)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 net/tap.c | 2 ++
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 1 file changed, 2 insertions(+)
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diff --git a/net/tap.c b/net/tap.c
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index 2b3a36f..89c4e19 100644
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--- a/net/tap.c
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+++ b/net/tap.c
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@@ -40,6 +40,7 @@
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 #include "qemu-common.h"
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 #include "qemu/cutils.h"
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 #include "qemu/error-report.h"
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+#include "qemu/sockets.h"
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 #include "net/tap.h"
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@@ -693,6 +694,7 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
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                 }
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                 return;
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             }
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+            qemu_set_nonblock(vhostfd);
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         } else {
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             vhostfd = open("/dev/vhost-net", O_RDWR);
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             if (vhostfd < 0) {
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-- 
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1.8.3.1
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