On Sat, 17 Aug 2019 19:51:03 +0800
hexin <hexin.op@xxxxxxxxx> wrote:
> 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.
>
> Fixes: 890ed578df82 ("vfio-pci: Use pci "try" reset interface")
> 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 | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
This looks good, but the subject is too long and I find the commit log
somewhat confusing. May I update these as follows?
vfio_pci: Restore original state on release
vfio_pci_enable() saves the device's initial configuration information
with the intent that it is restored in vfio_pci_disable(). However,
commit 890ed578df82 ("vfio-pci: Use pci "try" reset interface")
replaced the call to __pci_reset_function_locked(), which is not wrapped
in a state save and restore, with pci_try_reset_function(), which
overwrites the restored device state with the current state before
applying it to the device. Restore use of __pci_reset_function_locked()
to return to the desired behavior.
Thanks,
Alex
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 703948c..0220616 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -438,11 +438,20 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
> pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);
>
> /*
> - * Try to reset the device. The success of this is dependent on
> - * being able to lock the device, which is not always possible.
> + * Try to get the locks ourselves to prevent a deadlock. The
> + * success of this is dependent on being able to lock the device,
> + * which is not always possible.
> + * We can not use the "try" reset interface here, which will
> + * overwrite the previously restored configuration information.
> */
> - 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:
