[PATCH] vdpa/ifc: add live migration for block device

[Andy Pei <andy.pei@intel.com>]

When we use "sw-live-migration=1" in arguments, we run in SW assisted 
live migration mode.

In SW assisted live migration mode, driver will stop the device and
setup a mediated virtio ring to relay the communication between the
virtio driver and the VDPA device.

For block devices, we have to make sure that each IO is completed.
When we terminate the above mediated virtio ring, we stop 
notifying queue about new IOs, wait for all the in-flight IOs to 
be completed.

Signed-off-by: Andy Pei <andy.pei@intel.com>
---
 drivers/vdpa/ifc/ifcvf_vdpa.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/vdpa/ifc/ifcvf_vdpa.c b/drivers/vdpa/ifc/ifcvf_vdpa.c
index 49d68ad..17838ac 100644
--- a/drivers/vdpa/ifc/ifcvf_vdpa.c
+++ b/drivers/vdpa/ifc/ifcvf_vdpa.c
@@ -865,8 +865,30 @@ struct rte_vdpa_dev_info {
 	struct ifcvf_hw *hw = &internal->hw;
 	uint64_t m_vring_iova = IFCVF_MEDIATED_VRING;
 	uint64_t size, len;
+	u32 ring_state = 0;
 
 	vid = internal->vid;
+
+	/* to make sure no packet is lost for blk device
+	 * do not stop until last_avail_idx == last_used_idx
+	 */
+	if (internal->hw.device_type == IFCVF_BLK) {
+		for (i = 0; i < hw->nr_vring; i++) {
+			do {
+				if (hw->lm_cfg != NULL)
+					ring_state = *(u32 *)(hw->lm_cfg +
+						IFCVF_LM_RING_STATE_OFFSET +
+						i * IFCVF_LM_CFG_SIZE);
+				hw->vring[i].last_avail_idx =
+					(u16)(ring_state & IFCVF_16_BIT_MASK);
+				hw->vring[i].last_used_idx =
+					(u16)(ring_state >> 16);
+				usleep(10);
+			} while (hw->vring[i].last_avail_idx !=
+				hw->vring[i].last_used_idx);
+		}
+	}
+
 	ifcvf_stop_hw(hw);
 
 	for (i = 0; i < hw->nr_vring; i++) {
-- 
1.8.3.1