[PATCH v3 10/10] vfio: 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 | 35 ++++++++++++++++++++++++++++++++++-
 hw/vfio/pci.h |  2 ++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index c5e6fe61cb..64cf8e07d9 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -40,6 +40,9 @@
 #include "pci.h"
 #include "trace.h"
 #include "qapi/error.h"
+#include "migration/blocker.h"
+#include "qemu/option.h"
+#include "qemu/option_int.h"
 
 #define TYPE_VFIO_PCI "vfio-pci"
 #define PCI_VFIO(obj)    OBJECT_CHECK(VFIOPCIDevice, obj, TYPE_VFIO_PCI)
@@ -2698,6 +2701,12 @@ static void vfio_unregister_req_notifier(VFIOPCIDevice *vdev)
     vdev->req_enabled = false;
 }
 
+static int has_net_failover_arg(void *opaque, const char *name,
+                           const char *value, Error **errp)
+{
+    return (strcmp(name, "net_failover_pair_id") == 0);
+}
+
 static void vfio_realize(PCIDevice *pdev, Error **errp)
 {
     VFIOPCIDevice *vdev = PCI_VFIO(pdev);
@@ -2710,6 +2719,20 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     int groupid;
     int i, ret;
     bool is_mdev;
+    uint16_t class_id;
+
+    if (qemu_opt_foreach(pdev->qdev.opts, has_net_failover_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 ||
@@ -2812,6 +2835,14 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         goto error;
     }
 
+    if (vdev->net_failover_pair_id != NULL) {
+        class_id = pci_get_word(pdev->config + PCI_CLASS_DEVICE);
+        if (class_id != PCI_CLASS_NETWORK_ETHERNET) {
+            error_setg(errp, "failover device is not an Ethernet device");
+            goto error;
+        }
+    }
+
     /* vfio emulates a lot for us, but some bits need extra love */
     vdev->emulated_config_bits = g_malloc0(vdev->config_size);
 
@@ -3110,6 +3141,8 @@ static Property vfio_pci_dev_properties[] = {
                             display, ON_OFF_AUTO_OFF),
     DEFINE_PROP_UINT32("xres", VFIOPCIDevice, display_xres, 0),
     DEFINE_PROP_UINT32("yres", VFIOPCIDevice, display_yres, 0),
+    DEFINE_PROP_STRING("net_failover_pair_id", VFIOPCIDevice,
+            net_failover_pair_id),
     DEFINE_PROP_UINT32("x-intx-mmap-timeout-ms", VFIOPCIDevice,
                        intx.mmap_timeout, 1100),
     DEFINE_PROP_BIT("x-vga", VFIOPCIDevice, features,
@@ -3152,7 +3185,7 @@ 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 834a90d646..da4417071a 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -134,6 +134,7 @@ typedef struct VFIOPCIDevice {
     PCIHostDeviceAddress host;
     EventNotifier err_notifier;
     EventNotifier req_notifier;
+    char *net_failover_pair_id;
     int (*resetfn)(struct VFIOPCIDevice *);
     uint32_t vendor_id;
     uint32_t device_id;
@@ -168,6 +169,7 @@ 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