[PATCH] vfio_pci: Replace pci_try_reset_function() with __pci_reset_function_locked() to ensure that the pci device configuration space is restored to its original state

From: hexin
Date: Thu Aug 15 2019 - 23:33:57 EST


In vfio_pci_enable(), save the device's initial configuration information
and then restore the configuration in vfio_pci_disable(). However, the
execution result is not the same. Since the pci_try_reset_function()
function saves the current state before resetting, the configuration
information restored by pci_load_and_free_saved_state() will be
overwritten. The __pci_reset_function_locked() function can be used
to prevent the configuration space from being overwritten.

Signed-off-by: hexin <hexin15@xxxxxxxxx>
Signed-off-by: Liu Qi <liuqi16@xxxxxxxxx>
Signed-off-by: Zhang Yu <zhangyu31@xxxxxxxxx>
---
drivers/vfio/pci/vfio_pci.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 703948c..3c93492 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -441,8 +441,14 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
* Try to reset the device. The success of this is dependent on
* being able to lock the device, which is not always possible.
*/
- if (vdev->reset_works && !pci_try_reset_function(pdev))
- vdev->needs_reset = false;
+ if (vdev->reset_works && pci_cfg_access_trylock(pdev)) {
+ if (device_trylock(&pdev->dev)) {
+ if (!__pci_reset_function_locked(pdev))
+ vdev->needs_reset = false;
+ device_unlock(&pdev->dev);
+ }
+ pci_cfg_access_unlock(pdev);
+ }

pci_restore_state(pdev);
out:
--
1.8.3.1