[Qemu-devel] [RFC 3/5] vfio: introduce new VFIO ioctl VFIO_DEVICE_PCI_STATUS_SET

[Yulei Zhang <yulei.zhang@intel.com>]

New VFIO ioctl VFIO_DEVICE_PCI_STATUS_SET is added to change the
vfio pci device status during the migration, stop the device on
the source side before fetch its status and start the deivce on
the target side after restore its status.

Signed-off-by: Yulei Zhang <yulei.zhang@intel.com>
---
 hw/vfio/pci.c              | 17 +++++++++++++++++
 linux-headers/linux/vfio.h | 15 +++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 7de4eb4..605a473 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -38,6 +38,7 @@
 static void vfio_disable_interrupts(VFIOPCIDevice *vdev);
 static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled);
 static VMStateDescription vfio_pci_vmstate;
+static void vfio_vm_change_state_handler(void *pv, int running, RunState state);
 
 /*
  * Disabling BAR mmaping can be slow, but toggling it around INTx can
@@ -2866,6 +2867,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
     vfio_register_err_notifier(vdev);
     vfio_register_req_notifier(vdev);
     vfio_setup_resetfn_quirk(vdev);
+    qemu_add_vm_change_state_handler(vfio_vm_change_state_handler, vdev);
 
     return;
 
@@ -2948,6 +2950,21 @@ post_reset:
     vfio_pci_post_reset(vdev);
 }
 
+static void vfio_vm_change_state_handler(void *pv, int running, RunState state)
+{
+    VFIOPCIDevice *vdev = pv;
+    struct vfio_pci_status_set *vfio_status;
+    int argsz = sizeof(*vfio_status);
+
+    vfio_status = g_malloc0(argsz);
+    vfio_status->argsz = argsz;
+    vfio_status->flags = running ? VFIO_DEVICE_PCI_START :
+				  VFIO_DEVICE_PCI_STOP;
+
+    ioctl(vdev->vbasedev.fd, VFIO_DEVICE_PCI_STATUS_SET, vfio_status);
+    g_free(vfio_status);
+}
+
 static int vfio_device_put(QEMUFile *f, void *pv, size_t size, VMStateField *field,
                             QJSON *vmdesc)
 {
diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
index c87d05c..fa17848 100644
--- a/linux-headers/linux/vfio.h
+++ b/linux-headers/linux/vfio.h
@@ -487,6 +487,21 @@ struct vfio_pci_hot_reset {
 
 #define VFIO_DEVICE_PCI_HOT_RESET	_IO(VFIO_TYPE, VFIO_BASE + 13)
 
+/**
+ * VFIO_DEVICE_PCI_STATUS_SET - _IOW(VFIO_TYPE, VFIO_BASE + 14,
+ *				    struct vfio_pci_status_set)
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_pci_status_set{
+	__u32	argsz;
+	__u32	flags;
+#define VFIO_DEVICE_PCI_STOP  (1 << 0)
+#define VFIO_DEVICE_PCI_START (1 << 1)
+};
+
+#define VFIO_DEVICE_PCI_STATUS_SET	_IO(VFIO_TYPE, VFIO_BASE + 14)
+
 /* -------- API for Type1 VFIO IOMMU -------- */
 
 /**
-- 
2.7.4