From dd64ec40a29739464cfe886818588bb9946b8d8d Mon Sep 17 00:00:00 2001
Message-Id: <dd64ec40a29739464cfe886818588bb9946b8d8d@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Fri, 27 Jan 2023 13:59:08 +0100
Subject: [PATCH] qemuProcessLaunch: Tighten rules for external devices wrt
 incoming migration
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When starting a guest, helper processes are started first. But
they need a bit of special handling. Just consider a regular cold
boot and an incoming migration. For instance, in case of swtpm
with its state on a shared volume, we want to set label on the
state for the cold boot case, but don't want to touch the label
in case of incoming migration (because the source very
specifically did not restore it either).

Until now, these two cases were differentiated by testing
@incoming against NULL. And while that makes sense for other
aspects of domain startup, for external devices we need a bit
more, because a restore from a save file is also 'incoming
migration'.

Now, there is a difference between regular migration and restore
from a save file. In the former case we do not want to set
seclabels in the save state. BUT, in the latter case we do need
to set them, because the code that saves the machine restored
seclabels.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2161557
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
(cherry picked from commit 5c4007ddc6c29632b5cc96ab4ef81ebb7797d1bb)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_process.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 2de87211fb..1217fb1856 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -7620,6 +7620,7 @@ qemuProcessLaunch(virConnectPtr conn,
     size_t nnicindexes = 0;
     g_autofree int *nicindexes = NULL;
     unsigned long long maxMemLock = 0;
+    bool incomingMigrationExtDevices = false;
 
     VIR_DEBUG("conn=%p driver=%p vm=%p name=%s id=%d asyncJob=%d "
               "incoming.uri=%s "
@@ -7674,7 +7675,13 @@ qemuProcessLaunch(virConnectPtr conn,
     if (qemuDomainSchedCoreStart(cfg, vm) < 0)
         goto cleanup;
 
-    if (qemuExtDevicesStart(driver, vm, incoming != NULL) < 0)
+    /* For external devices the rules of incoming migration are a bit stricter,
+     * than plain @incoming != NULL. They need to differentiate between
+     * incoming migration and restore from a save file.  */
+    incomingMigrationExtDevices = incoming &&
+        vmop == VIR_NETDEV_VPORT_PROFILE_OP_MIGRATE_IN_START;
+
+    if (qemuExtDevicesStart(driver, vm, incomingMigrationExtDevices) < 0)
         goto cleanup;
 
     if (!(cmd = qemuBuildCommandLine(vm,
-- 
2.39.1