lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20250627162245.GA3513535-robh@kernel.org>
Date: Fri, 27 Jun 2025 11:22:45 -0500
From: Rob Herring <robh@...nel.org>
To: Herve Codina <herve.codina@...tlin.com>
Cc: Andrew Lunn <andrew@...n.ch>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Andi Shyti <andi.shyti@...nel.org>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Peter Rosin <peda@...ntia.se>,
	Derek Kiernan <derek.kiernan@....com>,
	Dragan Cvetic <dragan.cvetic@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Saravana Kannan <saravanak@...gle.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Mark Brown <broonie@...nel.org>, Len Brown <lenb@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Daniel Scally <djrscally@...il.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Wolfram Sang <wsa@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Davidlohr Bueso <dave@...olabs.net>,
	Dave Jiang <dave.jiang@...el.com>,
	Alison Schofield <alison.schofield@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Ira Weiny <ira.weiny@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	linux-kernel@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
	linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-spi@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-cxl@...r.kernel.org,
	Allan Nielsen <allan.nielsen@...rochip.com>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	Steen Hegelund <steen.hegelund@...rochip.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v3 18/28] of: property: Allow fw_devlink device-tree on
 x86 when PCI device-tree node creation is enabled

On Fri, Jun 13, 2025 at 03:47:58PM +0200, Herve Codina wrote:
> PCI drivers can use a device-tree overlay to describe the hardware
> available on the PCI board. This is the case, for instance, of the
> LAN966x PCI device driver.
> 
> Adding some more nodes in the device-tree overlay adds some more
> consumer/supplier relationship between devices instantiated from this
> overlay.
> 
> Those fw_node consumer/supplier relationships are handled by fw_devlink
> and are created based on the device-tree parsing done by the
> of_fwnode_add_links() function.
> 
> Those consumer/supplier links are needed in order to ensure a correct PM
> runtime management and a correct removal order between devices.
> 
> For instance, without those links a supplier can be removed before its
> consumers is removed leading to all kind of issue if this consumer still
> want the use the already removed supplier.
> 
> The support for the usage of an overlay from a PCI driver has been added
> on x86 systems in commit 1f340724419ed ("PCI: of: Create device tree PCI
> host bridge node").
> 
> In the past, support for fw_devlink on x86 had been tried but this
> support has been removed in commit 4a48b66b3f52 ("of: property: Disable
> fw_devlink DT support for X86"). Indeed, this support was breaking some
> x86 systems such as OLPC system and the regression was reported in [0].
> 
> Instead of disabling this support for all x86 system, a first approach
> would be to use a finer grain and disable this support only for the
> possible problematic subset of x86 systems (at least OLPC and CE4100).
> 
> This first approach could still leads to issues. Indeed, the list of
> possible problematic system and the way to identify them using Kconfig
> symbols is not well defined and so some system can be missed leading to
> kernel regressions on those missing systems.
> 
> Use an other way and enable the support on x86 system only when this
> support is needed by some specific feature. The usage of a device-tree
> overlay by a PCI driver and thus the creation of PCI device-tree nodes
> is a feature that needs it.
> 
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> Link: https://lore.kernel.org/lkml/3c1f2473-92ad-bfc4-258e-a5a08ad73dd0@web.de/ [0]
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/of/property.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index c1feb631e383..8b5cfee696e2 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -1605,7 +1605,7 @@ static int of_fwnode_add_links(struct fwnode_handle *fwnode)
>  	const struct property *p;
>  	struct device_node *con_np = to_of_node(fwnode);
>  
> -	if (IS_ENABLED(CONFIG_X86))
> +	if (IS_ENABLED(CONFIG_X86) && !IS_ENABLED(CONFIG_PCI_DYNAMIC_OF_NODES))

I really want CONFIG_PCI_DYNAMIC_OF_NODES to go away at some point, not 
add more users. 

I think this should instead check for specific platforms not with 
kconfig symbols but DT properties. For ce4100, you can just check the 
root compatible string. For OLPC, there isn't a root compatible (in the 
DT I have). You could check for /architecture == OLPC instead. There's 
some virtualization guests using DT now too. I would think their DT's 
are simple enough to avoid any fw_devlink issues. 

Alternatively, we could perhaps make x86 fw_devlink default off and then 
enable it only when you create nodes. Maybe it has to be restricted a 
sub tree of the DT to avoid any later interactions if devices are 
unbound and rebound. Not a fully fleshed out idea...

Rob

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ