[libvirt] [PATCH 5/6] qemu: migration: warn if migrating with host-passthrough

[Jason J. Herne]

From: "Collin L. Walling" <walling at linux.vnet.ibm.com>

Warn the user when migrating a guest that is using the host-passthrough cpu
mode. host-passthrough is not migration safe because the host hypervisor is not
attempting to block features that may not exist on the destination host.

Signed-off-by: Collin L. Walling <walling at linux.vnet.ibm.com>
Signed-off-by: Jason J. Herne <jjherne at linux.vnet.ibm.com>
---
 src/qemu/qemu_migration.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index d4a55d8..f721de7 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -3151,6 +3151,10 @@ qemuMigrationBeginPhase(virQEMUDriverPtr driver,
     if (priv->job.asyncJob == QEMU_ASYNC_JOB_MIGRATION_OUT)
         qemuMigrationJobSetPhase(driver, vm, QEMU_MIGRATION_PHASE_BEGIN3);
 
+    if (vm->def->cpu && vm->def->cpu->mode == VIR_CPU_MODE_HOST_PASSTHROUGH)
+        VIR_WARN("cpu mode 'host-passthrough' may fail migration if destination"
+                 " machine is running an older cpu model.");
+
     if (!qemuMigrationIsAllowed(driver, vm, true, flags))
         goto cleanup;
 
-- 
1.9.1