[Qemu-devel] [PATCH 4/4] vfio/pci: unplug failover primary device before migration

[Jens Freimann <jfreimann@redhat.com>]

As usual block all vfio-pci devices from being migrated, but make an
exception for failover primary devices. This is achieved by setting
unmigratable to 0 but also add a migration blocker for all vfio-pci
devices except failover primary devices. These will be unplugged before
migration happens by the migration handler of the corresponding
virtio-net standby device.

Signed-off-by: Jens Freimann <jfreimann@redhat.com>
---
 hw/vfio/pci.c | 24 +++++++++++++++++++++++-
 hw/vfio/pci.h |  1 +
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 835249c61d..60cda7dbc9 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -34,6 +34,9 @@
 #include "pci.h"
 #include "trace.h"
 #include "qapi/error.h"
+#include "migration/blocker.h"
+#include "qemu/option.h"
+#include "qemu/option_int.h"
 
 #define MSIX_CAP_LENGTH 12
 
@@ -2803,6 +2806,12 @@ static void vfio_unregister_req_notifier(VFIOPCIDevice *vdev)
     vdev->req_enabled = false;
 }
 
+static int has_standby_arg(void *opaque, const char *name,
+                           const char *value, Error **errp)
+{
+    return strcmp(name, "standby") == 0;
+}
+
 static void vfio_realize(PCIDevice *pdev, Error **errp)
 {
     VFIOPCIDevice *vdev = PCI_VFIO(pdev);
@@ -2816,6 +2825,19 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     int i, ret;
     bool is_mdev;
 
+    if (qemu_opt_foreach(pdev->qdev.opts, has_standby_arg,
+                         (void *) pdev->qdev.opts, &err) == 0) {
+        error_setg(&vdev->migration_blocker,
+                "VFIO device doesn't support migration");
+        ret = migrate_add_blocker(vdev->migration_blocker, &err);
+        if (err) {
+            error_propagate(errp, err);
+            error_free(vdev->migration_blocker);
+        }
+    } else {
+        pdev->qdev.allow_unplug_during_migration = true;
+    }
+
     if (!vdev->vbasedev.sysfsdev) {
         if (!(~vdev->host.domain || ~vdev->host.bus ||
               ~vdev->host.slot || ~vdev->host.function)) {
@@ -3258,7 +3280,7 @@ static Property vfio_pci_dev_properties[] = {
 
 static const VMStateDescription vfio_pci_vmstate = {
     .name = "vfio-pci",
-    .unmigratable = 1,
+    .unmigratable = 0,
 };
 
 static void vfio_pci_dev_class_init(ObjectClass *klass, void *data)
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 1a87f91889..390ba2c767 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -170,6 +170,7 @@ typedef struct VFIOPCIDevice {
     bool no_vfio_ioeventfd;
     bool enable_ramfb;
     VFIODisplay *dpy;
+    Error *migration_blocker;
 } VFIOPCIDevice;
 
 uint32_t vfio_pci_read_config(PCIDevice *pdev, uint32_t addr, int len);
-- 
2.21.0