vos: add BE and FE status synchronization

Add udm synchronization between BE and FE.
1. Add handshake. When the VM which UDM run in shutdown
and BE do not have change to notify FE, running FE can know the BE
status change by check handshake mask.
The handshake mask lays in virtio header in share memory BAR. It is
checked every 2 seconds.
2. Add event interrupt. When the backend application exits normally
or the VM where the backend resides is shut down normally, BE can
trigger a interrupt, and notify FE the event.
3. Create /dev/virtio_shmemX which set auto or manual unresigter
virtio device by 'VIRTIO_SHMEM_IOCTL_AUTO_REMOVE'.
In this state, APP in user space can unregister the device by
'VIRTIO_SHMEM_IOCTL_UNREGISTER'.

Signed-off-by: Yuanyuan Zhao <yuanyuan.zhao@intel.com>

Author: Yuanyuan Zhao

drivers/virtio/virtio_guest_shm.c

@@ -130,18 +130,12 @@ static int virtio_ivshmem_probe(struct pci_dev *pci_dev,
 	vi_dev->notify_peer = virtio_guest_shm_notify_peer;
 	vi_dev->early_irq_handler = virtio_guest_shm_early_irq_handler;
 	vi_dev->priv = vi_data;
+	vi_dev->virtio_registered = false;
 
 	ret = virtio_shmem_probe(vi_dev);
 	if (ret)
 		goto err_enable;
 
-	ret = register_virtio_device(&vi_dev->vdev);
-	if (ret) {
-		dev_err(&pci_dev->dev, "failed to register device\n");
-		put_device(&vi_dev->vdev.dev);
-		goto err_enable;
-	}
-
 #ifdef CONFIG_VIRTIO_IVSHMEM_DEBUG
 	vi_dev->shmem_sz_used = (vi_dev->virtio_header->size
 		+ (chunk_size - 1)) & ~(chunk_size - 1);
@@ -166,7 +160,7 @@ static void virtio_ivshmem_remove(struct pci_dev *pci_dev)
 	struct virtio_shmem_device *vi_dev = pci_get_drvdata(pci_dev);
 	struct device *dev = get_device(&vi_dev->vdev.dev);
 
-	unregister_virtio_device(&vi_dev->vdev);
+	virtio_shmem_remove(vi_dev);
 	pci_disable_device(pci_dev);
 	put_device(dev);
 	kfree(vi_dev);

drivers/virtio/virtio_ivshmem.c

@@ -34,30 +34,6 @@ static void virtio_ivshmem_notify_peer(struct virtio_shmem_device *vi_dev, unsig
 	writel((vi_dev->peer_id << 16), &vi_data->ivshm_regs->doorbell);
 }
 
-static int virito_ivshmem_check_virtio_supports(struct pci_dev *pdev)
-{
-	unsigned long bar_start, bar_len;
-	void __iomem *bar_addr;
-	int vendor, err = -1;
-
-	bar_start = pci_resource_start(pdev, 2);
-	bar_len = pci_resource_len(pdev, 2);
-	if (bar_start && bar_len) {
-		if (pci_resource_flags(pdev, 2) & IORESOURCE_MEM) {
-			bar_addr = pci_iomap(pdev, 2, bar_len);
-			if (!bar_addr) {
-				dev_err(&pdev->dev, "Could not map memory BAR #%d\n", 2);
-				return -1;
-			}
-			vendor = readw(bar_addr + IVSHMEM_VENDOR_OFFSET);
-			if (vendor == PCI_VENDOR_ID_REDHAT_QUMRANET)
-				err = 0;
-			pci_iounmap(pdev, bar_addr);
-		}
-	}
-	return err;
-}
-
 static int virtio_ivshmem_probe(struct pci_dev *pci_dev,
 				const struct pci_device_id *pci_id)
 {
@@ -95,12 +71,6 @@ static int virtio_ivshmem_probe(struct pci_dev *pci_dev,
 
 	vi_dev->this_id = readl(&vi_data->ivshm_regs->ivpos);
 
-	ret = virito_ivshmem_check_virtio_supports(pci_dev);
-	if (ret != 0) {
-		dev_err(&pci_dev->dev, "not a virtio device\n");
-		goto err_enable;
-	}
-
 	section_sz = pci_resource_len(pci_dev, 2);
 	if (section_sz == 0) {
 		dev_err(&pci_dev->dev, "missing shared memory\n");
@@ -118,18 +88,12 @@ static int virtio_ivshmem_probe(struct pci_dev *pci_dev,
 	vi_dev->shmem_sz = section_sz;
 	vi_dev->notify_peer = virtio_ivshmem_notify_peer;
 	vi_dev->priv = vi_data;
+	vi_dev->virtio_registered = false;
 
 	ret = virtio_shmem_probe(vi_dev);
 	if (ret)
 		goto err_enable;
 
-	ret = register_virtio_device(&vi_dev->vdev);
-	if (ret) {
-		dev_err(&pci_dev->dev, "failed to register device\n");
-		put_device(&vi_dev->vdev.dev);
-		goto err_enable;
-	}
-
 #ifdef CONFIG_VIRTIO_IVSHMEM_DEBUG
 	vi_dev->shmem_sz_used = (vi_dev->virtio_header->size + (chunk_size - 1))
 		& ~(chunk_size - 1);
@@ -154,7 +118,7 @@ static void virtio_ivshmem_remove(struct pci_dev *pci_dev)
 	struct virtio_shmem_device *vi_dev = pci_get_drvdata(pci_dev);
 	struct device *dev = get_device(&vi_dev->vdev.dev);
 
-	unregister_virtio_device(&vi_dev->vdev);
+	virtio_shmem_remove(vi_dev);
 	pci_disable_device(pci_dev);
 	put_device(dev);
 	kfree(vi_dev);