vfio: Add save and load functions for VFIO PCI devices

Added functions to save and restore PCI device specific data,
specifically config space of PCI device.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/vfio/pci.c

@@ -41,6 +41,7 @@
 #include "trace.h"
 #include "qapi/error.h"
 #include "migration/blocker.h"
+#include "migration/qemu-file.h"
 
 #define TYPE_VFIO_PCI_NOHOTPLUG "vfio-pci-nohotplug"
 
@@ -2401,11 +2402,61 @@ static Object *vfio_pci_get_object(VFIODevice *vbasedev)
     return OBJECT(vdev);
 }
 
+static bool vfio_msix_present(void *opaque, int version_id)
+{
+    PCIDevice *pdev = opaque;
+
+    return msix_present(pdev);
+}
+
+const VMStateDescription vmstate_vfio_pci_config = {
+    .name = "VFIOPCIDevice",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_PCI_DEVICE(pdev, VFIOPCIDevice),
+        VMSTATE_MSIX_TEST(pdev, VFIOPCIDevice, vfio_msix_present),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void vfio_pci_save_config(VFIODevice *vbasedev, QEMUFile *f)
+{
+    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
+
+    vmstate_save_state(f, &vmstate_vfio_pci_config, vdev, NULL);
+}
+
+static int vfio_pci_load_config(VFIODevice *vbasedev, QEMUFile *f)
+{
+    VFIOPCIDevice *vdev = container_of(vbasedev, VFIOPCIDevice, vbasedev);
+    PCIDevice *pdev = &vdev->pdev;
+    int ret;
+
+    ret = vmstate_load_state(f, &vmstate_vfio_pci_config, vdev, 1);
+    if (ret) {
+        return ret;
+    }
+
+    vfio_pci_write_config(pdev, PCI_COMMAND,
+                          pci_get_word(pdev->config + PCI_COMMAND), 2);
+
+    if (msi_enabled(pdev)) {
+        vfio_msi_enable(vdev);
+    } else if (msix_enabled(pdev)) {
+        vfio_msix_enable(vdev);
+    }
+
+    return ret;
+}
+
 static VFIODeviceOps vfio_pci_ops = {
     .vfio_compute_needs_reset = vfio_pci_compute_needs_reset,
     .vfio_hot_reset_multi = vfio_pci_hot_reset_multi,
     .vfio_eoi = vfio_intx_eoi,
     .vfio_get_object = vfio_pci_get_object,
+    .vfio_save_config = vfio_pci_save_config,
+    .vfio_load_config = vfio_pci_load_config,
 };
 
 int vfio_populate_vga(VFIOPCIDevice *vdev, Error **errp)

include/hw/vfio/vfio-common.h

@@ -120,6 +120,8 @@ struct VFIODeviceOps {
     int (*vfio_hot_reset_multi)(VFIODevice *vdev);
     void (*vfio_eoi)(VFIODevice *vdev);
     Object *(*vfio_get_object)(VFIODevice *vdev);
+    void (*vfio_save_config)(VFIODevice *vdev, QEMUFile *f);
+    int (*vfio_load_config)(VFIODevice *vdev, QEMUFile *f);
 };
 
 typedef struct VFIOGroup {