From b84c055e38c1075af7ff51c9809977a48118ded2 Mon Sep 17 00:00:00 2001
Message-Id: <b84c055e38c1075af7ff51c9809977a48118ded2@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 4 Sep 2018 10:41:02 +0200
Subject: [PATCH] virDomainNetDefCheckABIStability: Check for MTU change too
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RHEL-7.6: https://bugzilla.redhat.com/show_bug.cgi?id=1623157
RHEL-8.0: https://bugzilla.redhat.com/show_bug.cgi?id=1623158

Changing MTU on a running guest is not possible and trying to do
so made us face many problems. That's why we forbid it in
5f44d7e357f61f7. However, there is still one possible path where
users can sneak in change: migration XML.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
(cherry picked from commit 4ea3693104c03ac40a6595f5b9bcda58fa18afe7)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/conf/domain_conf.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 35f944d92a..a881b43b51 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -21628,6 +21628,13 @@ virDomainNetDefCheckABIStability(virDomainNetDefPtr src,
         return false;
     }
 
+    if (src->mtu != dst->mtu) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target network card MTU %d does not match source %d"),
+                       dst->mtu, src->mtu);
+        return false;
+    }
+
     if (src->virtio && dst->virtio &&
         !virDomainVirtioOptionsCheckABIStability(src->virtio, dst->virtio))
         return false;
-- 
2.18.0