vfio-pci: Log device requests more verbosely

Log some clues indicating whether the user is receiving device
request interfaces or not listening.  This can help indicate why a
driver unbind is blocked or explain why QEMU automatically unplugged
a device from the VM.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 69fab0fd15aec4a5cb05c870984dc7e4bc9dcad4..e9851add6f4ef251defba65a3bab9af359b60b3a 100644 (file)
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -907,8 +907,14 @@ static void vfio_pci_request(void *device_data, unsigned int count)
        mutex_lock(&vdev->igate);
 
        if (vdev->req_trigger) {
-               dev_dbg(&vdev->pdev->dev, "Requesting device from user\n");
+               if (!(count % 10))
+                       dev_notice_ratelimited(&vdev->pdev->dev,
+                               "Relaying device request to user (#%u)\n",
+                               count);
                eventfd_signal(vdev->req_trigger, 1);
+       } else if (count == 0) {
+               dev_warn(&vdev->pdev->dev,
+                       "No device request channel registered, blocked until released by user\n");
        }
 
        mutex_unlock(&vdev->igate);