[Qemu-devel] [RFC PATCH V4 1/4] vfio: introduce a new VFIO subregion for mdev device migration support

[Yulei Zhang]

New VFIO sub region VFIO_REGION_SUBTYPE_DEVICE_STATE is added
to fetch and restore the status of mdev device vGPU during the
live migration.

Signed-off-by: Yulei Zhang <yulei.zh...@intel.com>
---
 hw/vfio/pci.c              | 25 ++++++++++++++++++++++++-
 hw/vfio/pci.h              |  2 ++
 linux-headers/linux/vfio.h |  9 ++++++---
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index c977ee3..f98a9dd 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -32,6 +32,7 @@
 #include "pci.h"
 #include "trace.h"
 #include "qapi/error.h"
+#include "migration/blocker.h"
 
 #define MSIX_CAP_LENGTH 12
 
@@ -2821,6 +2822,25 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         vfio_vga_quirk_setup(vdev);
     }
 
+    struct vfio_region_info *device_state;
+    /* device state region setup */
+    if (!vfio_get_dev_region_info(&vdev->vbasedev,
+                VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
+                VFIO_REGION_SUBTYPE_DEVICE_STATE, &device_state)) {
+        memcpy(&vdev->device_state, device_state,
+               sizeof(struct vfio_region_info));
+        g_free(device_state);
+    } else {
+        error_setg(&vdev->migration_blocker,
+                "Migration disabled: cannot support device state region");
+        migrate_add_blocker(vdev->migration_blocker, &err);
+        if (err) {
+            error_propagate(errp, err);
+            error_free(vdev->migration_blocker);
+            goto error;
+        }
+    }
+
     for (i = 0; i < PCI_ROM_SLOT; i++) {
         vfio_bar_quirk_setup(vdev, i);
     }
@@ -2884,6 +2904,10 @@ out_teardown:
     vfio_teardown_msi(vdev);
     vfio_bars_exit(vdev);
 error:
+    if (vdev->migration_blocker) {
+        migrate_del_blocker(vdev->migration_blocker);
+        error_free(vdev->migration_blocker);
+    }
     error_prepend(errp, ERR_PREFIX, vdev->vbasedev.name);
 }
 
@@ -3009,7 +3033,6 @@ static Property vfio_pci_dev_properties[] = {
 
 static const VMStateDescription vfio_pci_vmstate = {
     .name = "vfio-pci",
-    .unmigratable = 1,
 };
 
 static void vfio_pci_dev_class_init(ObjectClass *klass, void *data)
diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 502a575..0ee1724 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -116,6 +116,8 @@ typedef struct VFIOPCIDevice {
     VFIOBAR bars[PCI_NUM_REGIONS - 1]; /* No ROM */
     VFIOVGA *vga; /* 0xa0000, 0x3b0, 0x3c0 */
     void *igd_opregion;
+    struct vfio_region_info device_state;
+    Error *migration_blocker;
     PCIHostDeviceAddress host;
     EventNotifier err_notifier;
     EventNotifier req_notifier;
diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
index 4312e96..e3380ad 100644
--- a/linux-headers/linux/vfio.h
+++ b/linux-headers/linux/vfio.h
@@ -297,9 +297,12 @@ struct vfio_region_info_cap_type {
 #define VFIO_REGION_TYPE_PCI_VENDOR_MASK       (0xffff)
 
 /* 8086 Vendor sub-types */
-#define VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION (1)
-#define VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG (2)
-#define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG  (3)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION         (1)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG         (2)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG          (3)
+
+/* Mdev sub-type for device state save and restore */
+#define VFIO_REGION_SUBTYPE_DEVICE_STATE       (4)
 
 /**
  * VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,
-- 
2.7.4