[PATCH v2 2/3] virito_pci: add timeout to reset device operation

Max Gurtovoy
2021-04-08T08:11:19Z

According to the spec after writing 0 to device_status, the driver MUST
wait for a read of device_status to return 0 before reinitializing the
device. In case we have a device that won't return 0, the reset
operation will loop forever and cause the host/vm to stuck. Set timeout
for 3 minutes before giving up on the device.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
---
drivers/virtio/virtio_pci_modern.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index cc3412a96a17..dcee616e8d21 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -162,6 +162,7 @@ static int vp_reset(struct virtio_device *vdev)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
+ unsigned long timeout = jiffies + msecs_to_jiffies(180000);

/* 0 status means a reset. */
vp_modern_set_status(mdev, 0);
@@ -169,9 +170,16 @@ static int vp_reset(struct virtio_device *vdev)
* device_status to return 0 before reinitializing the device.
* This will flush out the status write, and flush in device writes,
* including MSI-X interrupts, if any.
+ * Set a timeout before giving up on the device.
*/
- while (vp_modern_get_status(mdev))
+ while (vp_modern_get_status(mdev)) {
+ if (time_after(jiffies, timeout)) {
+ dev_err(&vdev->dev, "virtio: device not ready. "
+ "Aborting. Try again later\n");
+ return -EAGAIN;
+ }
msleep(1);
+ }
/* Flush pending VQ/configuration callbacks. */
vp_synchronize_vectors(vdev);
return 0;
--
2.25.4