Re: [PATCH] PCI/portdrv: do not disable device on remove()

[Ryan Finnie]

On 05/22/2018 10:58 AM, Sinan Kaya wrote:
> 'Commit cc27b735ad3a ("PCI/portdrv: Turn off PCIe services during
> shutdown")' has been added to kernel to shutdown pending PCIe port
> service interrupts during reboot so that a newly started kexec kernel
> wouldn't observe pending interrupts.
> 
> pcie_port_device_remove() is disabling the root port and switches by
> calling pci_disable_device() after all PCIe service drivers are shutdown.
> 
> pci_disable_device() has a much wider impact then port service itself and
> it prevents all inbound transactions to reach to the system and impacts
> the entire PCI traffic behind the bridge.
> 
> Issue is that pcie_port_device_remove() doesn't maintain any coordination
> with the rest of the PCI device drivers in the system before clearing the
> bus master bit.
> 
> This has been found to cause crashes on HP DL360 Gen9 machines during
> reboot. Besides, kexec is already clearing the bus master bit in
> pci_device_shutdown() after all PCI drivers are removed.

FAOD, this problem has been observed on both DL360 Gen9 and DL380 Gen9,
in both EFI and legacy modes.  I suspect all Gen9 models with the P89
firmware base.

> Just remove the extra clear here.

Thank you!  Fix tested on:

- DL360 Gen9
- DL380 Gen9
- DL380 Gen10 (confirmed no regression)
- DL380 G7 (confirmed no regression)

> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=199779
> Fixes: cc27b735ad3a ("PCI/portdrv: Turn off PCIe services during shutdown")
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Ryan Finnie <ryan@xxxxxxxxxx>

Tested-by: Ryan Finnie <ryan@xxxxxxxxxx>