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    Subject[PATCH 4.14 20/68] vfio_pci: Restore original state on release
    Date
    From: hexin <hexin.op@gmail.com>

    [ Upstream commit 92c8026854c25093946e0d7fe536fd9eac440f06 ]

    vfio_pci_enable() saves the device's initial configuration information
    with the intent that it is restored in vfio_pci_disable(). However,
    the commit referenced in Fixes: below 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. Reinstate use of __pci_reset_function_locked() to return to
    the desired behavior.

    Fixes: 890ed578df82 ("vfio-pci: Use pci "try" reset interface")
    Signed-off-by: hexin <hexin15@baidu.com>
    Signed-off-by: Liu Qi <liuqi16@baidu.com>
    Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
    Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/vfio/pci/vfio_pci.c | 17 +++++++++++++----
    1 file changed, 13 insertions(+), 4 deletions(-)

    diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
    index 6f5cc67e343e7..15b1cd4ef5a77 100644
    --- a/drivers/vfio/pci/vfio_pci.c
    +++ b/drivers/vfio/pci/vfio_pci.c
    @@ -363,11 +363,20 @@ 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:
    --
    2.20.1


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