From: Michal Privoznik <mprivozn@redhat.com>
Date: Fri, 28 Jun 2024 07:56:46 +0000 (+0200)
Subject: qemu_domain: Set 'passt' net backend if 'default' is unsupported
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=8f34fd0c4cb3549e5d834234a20425c380bb2511;p=libvirt.git

qemu_domain: Set 'passt' net backend if 'default' is unsupported

It may happen that QEMU is compiled without SLIRP but with
support for passt. In such case it is acceptable to alter user
provided configuration and switch backend to passt as it offers
all the features as SLIRP.

Resolves: https://issues.redhat.com/browse/RHEL-45518
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
---

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 1a90311ca5..2134b11038 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -5975,12 +5975,25 @@ qemuDomainDeviceNetDefPostParse(virDomainNetDef *net,
                                 virQEMUCaps *qemuCaps)
 {
     if (net->type == VIR_DOMAIN_NET_TYPE_VDPA &&
-        !virDomainNetGetModelString(net))
+        !virDomainNetGetModelString(net)) {
         net->model = VIR_DOMAIN_NET_MODEL_VIRTIO;
-    else if (net->type != VIR_DOMAIN_NET_TYPE_HOSTDEV &&
+    } else if (net->type != VIR_DOMAIN_NET_TYPE_HOSTDEV &&
         !virDomainNetGetModelString(net) &&
-        virDomainNetResolveActualType(net) != VIR_DOMAIN_NET_TYPE_HOSTDEV)
+        virDomainNetResolveActualType(net) != VIR_DOMAIN_NET_TYPE_HOSTDEV) {
         net->model = qemuDomainDefaultNetModel(def, qemuCaps);
+    }
+
+    if (net->type == VIR_DOMAIN_NET_TYPE_USER &&
+        net->backend.type == VIR_DOMAIN_NET_BACKEND_DEFAULT) {
+        virDomainCapsDeviceNet netCaps = { };
+
+        virQEMUCapsFillDomainDeviceNetCaps(qemuCaps, &netCaps);
+
+        if (!VIR_DOMAIN_CAPS_ENUM_IS_SET(netCaps.backendType, VIR_DOMAIN_NET_BACKEND_DEFAULT) &&
+            VIR_DOMAIN_CAPS_ENUM_IS_SET(netCaps.backendType, VIR_DOMAIN_NET_BACKEND_PASST)) {
+            net->backend.type = VIR_DOMAIN_NET_BACKEND_PASST;
+        }
+    }
 
     return 0;
 }