> This reverts commit 43bb40c5b926 ("virtio_pci: Support surprise removal of
> virtio pci device").
>
> Virtio drivers and PCI devices have never fully supported true surprise (aka
> hot
> unplug) removal. Drivers historically continued processing and waiting for
> pending I/O and even continued synchronous device reset during surprise
> removal. Devices have also continued completing I/Os, doing DMA and allowing
> device reset after surprise removal to support such drivers.
>
> Supporting it correctly would require a new device capability and driver
> negotiation in the virtio specification to safely stop I/O and free queue
> memory.
> Failure to do so either breaks all the existing drivers with call trace
> listed in the
> commit or crashes the host on continuing the DMA. Hence, until such
> specification and devices are invented, restore the previous behavior of
> treating
> surprise removal as graceful removal to avoid regressions and maintain system
> stability same as before the commit 43bb40c5b926 ("virtio_pci: Support
> surprise
> removal of virtio pci device").
>
> As explained above, previous analysis of solving this only in driver was
> incomplete and non-reliable at [1] and at [2]; Hence reverting commit
> 43bb40c5b926 ("virtio_pci: Support surprise removal of virtio pci device") is
> still
> the best stand to restore failures of virtio net and block devices.
>
> [1]
> https://lore.kernel.org/virtualization/CY8PR12MB719506CC5613EB100BC6C638
> [email protected]/#t
> [2]
> https://lore.kernel.org/virtualization/[email protected]
> om/
>
> Fixes: 43bb40c5b926 ("virtio_pci: Support surprise removal of virtio pci
> device")
> Cc: [email protected]
> Reported-by: [email protected]
> Closes:
> https://lore.kernel.org/virtualization/c45dd68698cd47238c55fb73ca9b4741@b
> aidu.com/
> Signed-off-by: Parav Pandit <[email protected]>
Tested-by: Li RongQing <[email protected]>
Thanks
-Li
> ---
> drivers/virtio/virtio_pci_common.c | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c
> b/drivers/virtio/virtio_pci_common.c
> index d6d79af44569..dba5eb2eaff9 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -747,13 +747,6 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
> struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> struct device *dev = get_device(&vp_dev->vdev.dev);
>
> - /*
> - * Device is marked broken on surprise removal so that virtio upper
> - * layers can abort any ongoing operation.
> - */
> - if (!pci_device_is_present(pci_dev))
> - virtio_break_device(&vp_dev->vdev);
> -
> pci_disable_sriov(pci_dev);
>
> unregister_virtio_device(&vp_dev->vdev);
> --
> 2.26.2
