linux-kernel - Re: [PATCH] pci: account for sysfs-disabled reset in pci_{slot,bus}

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Message-ID: <Z5E1oHd8FQs46tZs@6121402-lcelt>
Date: Wed, 22 Jan 2025 12:14:56 -0600
From: Nishanth Aravamudan <naravamudan@...dia.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
	Alex Williamson <alex.williamson@...hat.com>,
	Raphael Norwitz <raphael.norwitz@...anix.com>,
	Amey Narkhede <ameynarkhede03@...il.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, Jason Gunthorpe <jgg@...dia.com>,
	Yishai Hadas <yishaih@...dia.com>,
	Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
	Kevin Tian <kevin.tian@...el.com>, kvm@...r.kernel.org
Subject: Re: [PATCH] pci: account for sysfs-disabled reset in
 pci_{slot,bus}_resettable

On Mon, Jan 13, 2025 at 05:25:40PM -0600, Bjorn Helgaas wrote:
> Please update subject line to match historical capitalization
> convention.

Thank you, I will fix in v2.

> 
> On Mon, Jan 06, 2025 at 03:52:31PM -0600, Nishanth Aravamudan wrote:
> > vfio_pci_ioctl_get_pci_hot_reset_info checks if either the vdev's slot
> > or bus is not resettable by calling pci_probe_reset_{slot,bus}. Those
> > functions in turn call pci_{slot,bus}_resettable() to see if the PCI
> > device supports reset.
> >
> > However, commit d88f521da3ef ("PCI: Allow userspace to query and set
> > device reset mechanism") added support for userspace to disable reset of
> > specific PCI devices (by echo'ing "" into reset_method) and
> > pci_{slot,bus}_resettable methods do not check pci_reset_supported() to
> > see if userspace has disabled reset. Therefore, if an administrator
> > disables PCI reset of a specific device, but then uses vfio-pci with
> > that device (e.g. with qemu), vfio-pci will happily end up issuing a
> > reset to that device.
> 
> Please consistently add "()" after function names.

Will fix in v2, as well.

-Nish