[libvirt] [PATCH v2] libvirt: xen: do not use ioemu type for any emulated NIC

[Stefan Bader]

> I think it would be better if we just centralized this logic, as in,
> only set that (type ioemu) bit in conditional rather than 2. Should
> be pretty straightforward.

Did you have something like below in mind?

-Stefan

>From a0e214fa6dea9bd66616f37246067a2c631f4184 Mon Sep 17 00:00:00 2001
From: Stefan Bader <stefan.bader at canonical.com>
Date: Thu, 12 Apr 2012 15:32:41 +0200
Subject: [PATCH] libvirt: xen: do not use ioemu type for any emulated NIC

When using the xm/xend stack to manage instances there is a bug
that causes the emulated interfaces to be unusable when the vif
config contains type=ioemu.

The current code already has a special quirk to not use this
keyword if no specific model is given for the emulated NIC
(defaulting to rtl8139).
Essentially it works because regardless of the type argument,i
the Xen stack always creates emulated and paravirt interfaces and
lets the guest decide which one to use. So neither xl nor xm stack
actually require the type keyword for emulated NICs.

[v2: move code around to have the exception in one case together]
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
 src/xenxs/xen_sxpr.c |   28 +++++++++++++++-------------
 src/xenxs/xen_xm.c   |   27 ++++++++++++++-------------
 2 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/src/xenxs/xen_sxpr.c b/src/xenxs/xen_sxpr.c
index e1bbd76..3a56345 100644
--- a/src/xenxs/xen_sxpr.c
+++ b/src/xenxs/xen_sxpr.c
@@ -1999,20 +1999,22 @@ xenFormatSxprNet(virConnectPtr conn,
         if (def->model != NULL)
             virBufferEscapeSexpr(buf, "(model '%s')", def->model);
     }
-    else if (def->model == NULL) {
-        /*
-         * apparently (type ioemu) breaks paravirt drivers on HVM so skip
-         * this from XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU
-         */
-        if (xendConfigVersion <= XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU)
-            virBufferAddLit(buf, "(type ioemu)");
-    }
-    else if (STREQ(def->model, "netfront")) {
-        virBufferAddLit(buf, "(type netfront)");
-    }
     else {
-        virBufferEscapeSexpr(buf, "(model '%s')", def->model);
-        virBufferAddLit(buf, "(type ioemu)");
+        if (def->model != NULL && STREQ(def->model, "netfront")) {
+            virBufferAddLit(buf, "(type netfront)");
+        }
+        else {
+            if (def->model != NULL) {
+                virBufferEscapeSexpr(buf, "(model '%s')", def->model);
+            }
+            /*
+             * apparently (type ioemu) breaks paravirt drivers on HVM so skip
+             * this from XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU
+             */
+            if (xendConfigVersion <= XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU) {
+                virBufferAddLit(buf, "(type ioemu)");
+            }
+        }
     }
 
     if (!isAttach)
diff --git a/src/xenxs/xen_xm.c b/src/xenxs/xen_xm.c
index d65e97a..93a26f9 100644
--- a/src/xenxs/xen_xm.c
+++ b/src/xenxs/xen_xm.c
@@ -1381,20 +1381,21 @@ static int xenFormatXMNet(virConnectPtr conn,
         if (net->model != NULL)
             virBufferAsprintf(&buf, ",model=%s", net->model);
     }
-    else if (net->model == NULL) {
-        /*
-         * apparently type ioemu breaks paravirt drivers on HVM so skip this
-         * from XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU
-         */
-        if (xendConfigVersion <= XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU)
-            virBufferAddLit(&buf, ",type=ioemu");
-    }
-    else if (STREQ(net->model, "netfront")) {
-        virBufferAddLit(&buf, ",type=netfront");
-    }
     else {
-        virBufferAsprintf(&buf, ",model=%s", net->model);
-        virBufferAddLit(&buf, ",type=ioemu");
+        if (net->model != NULL && STREQ(net->model, "netfront")) {
+            virBufferAddLit(&buf, ",type=netfront");
+        }
+        else {
+            if (net->model != NULL)
+                virBufferAsprintf(&buf, ",model=%s", net->model);
+
+            /*
+             * apparently type ioemu breaks paravirt drivers on HVM so skip this
+             * from XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU
+             */
+            if (xendConfigVersion <= XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU)
+                virBufferAddLit(&buf, ",type=ioemu");
+        }
     }
 
     if (net->ifname)
-- 
1.7.9.5