Fix QEMU start when KVM is not loaded (rhbz#1875327)

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

0001-qemu_namespace-Be-tolerant-to-non-existent-files-whe.patch

@@ -0,0 +1,79 @@
+From 8abd1ffed18394a6212c469cb2c7b6cc28a122d2 Mon Sep 17 00:00:00 2001
+From: Michal Privoznik <mprivozn@redhat.com>
+Date: Thu, 3 Sep 2020 18:07:43 +0200
+Subject: [PATCH] qemu_namespace: Be tolerant to non-existent files when
+ populating /dev
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+In 6.7.0 release I've changed how domain namespace is built and
+populated. Previously it used to be done from a pre-exec hook
+(ran in the forked off child, just before dropping all privileges
+and exec()-ing QEMU), which not only meant we had to have two
+different code paths for creating a node in domain's namespace
+(one for this pre-exec hook, the other for hotplug ran from the
+daemon), it also proved problematic because it was leaking FDs
+into QEMU process.
+
+To mitigate this problem, we've not only ditched libdevmapper
+from the NS population process, I've also dropped the pre-exec
+code and let the NS be populated from the daemon (using the
+hotplug code). But, I was not careful when doing so, because the
+pre-exec code was tolerant to files that doesn't exist, while
+this new code isn't. For instance, the very first thing that is
+done when the new NS is created is it's populated with
+@defaultDeviceACL which contain files like /dev/null, /dev/zero,
+/dev/random and /dev/kvm (and others).  While the rest will
+probably exist every time, /dev/kvm might not and thus the new
+code I wrote has to be tolerant to that.
+
+Of course, users can override the @defaultDeviceACL (by setting
+cgroup_device_acl in qemu.conf) and remove /dev/kvm (which is
+acceptable workaround), but we definitely want libvirt to work
+out of the box even on hosts without KVM.
+
+Fixes: 9048dc4e627ddf33996084167bece7b5fb83b0bc
+Reported-by: Daniel P. Berrangé <berrange@redhat.com>
+Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
+Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
+Reviewed-by: Ján Tomko <jtomko@redhat.com>
+---
+ src/qemu/qemu_namespace.c | 12 +++++++++++-
+ 1 file changed, 11 insertions(+), 1 deletion(-)
+
+diff --git a/src/qemu/qemu_namespace.c b/src/qemu/qemu_namespace.c
+index 454d6a7b4d..87f4fd8d58 100644
+--- a/src/qemu/qemu_namespace.c
++++ b/src/qemu/qemu_namespace.c
+@@ -1094,6 +1094,9 @@ qemuNamespaceMknodItemInit(qemuNamespaceMknodItemPtr item,
+     item->file = file;
+ 
+     if (g_lstat(file, &item->sb) < 0) {
++        if (errno == ENOENT)
++            return -2;
++
+         virReportSystemError(errno,
+                              _("Unable to access %s"), file);
+         return -1;
+@@ -1168,9 +1171,16 @@ qemuNamespacePrepareOneItem(qemuNamespaceMknodDataPtr data,
+ 
+     while (1) {
+         qemuNamespaceMknodItem item = { 0 };
++        int rc;
+ 
+-        if (qemuNamespaceMknodItemInit(&item, cfg, vm, next) < 0)
++        rc = qemuNamespaceMknodItemInit(&item, cfg, vm, next);
++        if (rc == -2) {
++            /* @file doesn't exist. We can break here. */
++            break;
++        } else if (rc < 0) {
++            /* Some other (critical) error. */
+             return -1;
++        }
+ 
+         if (STRPREFIX(next, QEMU_DEVPREFIX)) {
+             for (i = 0; i < ndevMountsPath; i++) {
+-- 
+2.26.2
+

libvirt.spec

@@ -211,7 +211,7 @@
 Summary: Library providing a simple virtualization API
 Name: libvirt
 Version: 6.7.0
-Release: 1%{?dist}
+Release: 2%{?dist}
 License: LGPLv2+
 URL: https://libvirt.org/
 
@@ -219,6 +219,7 @@ URL: https://libvirt.org/
     %define mainturl stable_updates/
 %endif
 Source: https://libvirt.org/sources/%{?mainturl}libvirt-%{version}.tar.xz
+Patch1: 0001-qemu_namespace-Be-tolerant-to-non-existent-files-whe.patch
 
 Requires: libvirt-daemon = %{version}-%{release}
 Requires: libvirt-daemon-config-network = %{version}-%{release}
@@ -1964,6 +1965,9 @@ exit 0
 
 
 %changelog
+* Fri Sep  4 2020 Daniel P. Berrangé <berrange@redhat.com> - 6.7.0-2
+- Fix QEMU start when KVM is not loaded (rhbz#1875327)
+
 * Tue Sep 01 2020 Cole Robinson <crobinso@redhat.com> - 6.7.0-1
 - Update to version 6.7.0