* [PATCH v3] vfio_pci: Restore original state on release
@ 2019-08-22 3:35 hexin
2019-08-23 20:45 ` Alex Williamson
0 siblings, 1 reply; 2+ messages in thread
From: hexin @ 2019-08-22 3:35 UTC (permalink / raw)
To: Alex Williamson, kvm, linux-pci, linux-kernel; +Cc: hexin, Liu Qi, Zhang Yu
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>
---
v2->v3:
- change commit log
v1->v2:
- add fixes tag
- add comment to warn
[1] https://lore.kernel.org/linux-pci/1565926427-21675-1-git-send-email-hexin15@baidu.com
[2] https://lore.kernel.org/linux-pci/1566042663-16694-1-git-send-email-hexin15@baidu.com
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 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:
--
1.8.3.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v3] vfio_pci: Restore original state on release
2019-08-22 3:35 [PATCH v3] vfio_pci: Restore original state on release hexin
@ 2019-08-23 20:45 ` Alex Williamson
0 siblings, 0 replies; 2+ messages in thread
From: Alex Williamson @ 2019-08-23 20:45 UTC (permalink / raw)
To: hexin; +Cc: kvm, linux-pci, linux-kernel, hexin, Liu Qi, Zhang Yu
On Thu, 22 Aug 2019 11:35:19 +0800
hexin <hexin.op@gmail.com> wrote:
> 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>
> ---
Applied to vfio next branch for v5.4. Thanks,
Alex
> v2->v3:
> - change commit log
> v1->v2:
> - add fixes tag
> - add comment to warn
>
> [1] https://lore.kernel.org/linux-pci/1565926427-21675-1-git-send-email-hexin15@baidu.com
> [2] https://lore.kernel.org/linux-pci/1566042663-16694-1-git-send-email-hexin15@baidu.com
>
> 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 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:
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-08-22 3:35 [PATCH v3] vfio_pci: Restore original state on release hexin
2019-08-23 20:45 ` Alex Williamson
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