On 14.08.2015, at 09:43, Will Deacon [off-list ref] wrote:

On Fri, Aug 14, 2015 at 05:40:51PM +0100, Bjorn Helgaas wrote:

quoted

On Fri, Aug 14, 2015 at 05:19:17PM +0100, Marc Zyngier wrote:

quoted

When pci-host-generic looks for the probe-only property, it seems
to trust the DT to be correctly written, and assumes that there
is a parameter to the property.

Unfortunately, this is not always the case, and some firmware expose
this property naked. The driver ends up making a decision based on
whatever the property pointer points to, which is likely to be junk.

Switch to the common of_pci.c implementation that doesn't suffer
from this problem.

Signed-off-by: Marc Zyngier <redacted>
---
drivers/pci/host/pci-host-generic.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
index 265dd25..545ff4e 100644
--- a/drivers/pci/host/pci-host-generic.c
+++ b/drivers/pci/host/pci-host-generic.c

@@ -210,7 +210,6 @@ static int gen_pci_probe(struct platform_device *pdev)

	int err;
	const char *type;
	const struct of_device_id *of_id;
-	const int *prop;
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct gen_pci *pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);

@@ -225,13 +224,7 @@ static int gen_pci_probe(struct platform_device *pdev)

		return -EINVAL;
	}

-	prop = of_get_property(of_chosen, "linux,pci-probe-only", NULL);
-	if (prop) {
-		if (*prop)
-			pci_add_flags(PCI_PROBE_ONLY);
-		else
-			pci_clear_flags(PCI_PROBE_ONLY);
-	}
+	of_pci_check_probe_only(of_chosen);

Do we need support for pci-probe-only in pci-host-generic at all?
You're removing the use in amd-overdrive.dts, and there are no other
DTs in the kernel tree that mention it.

If we can live without it, that would be nice.  It seems like a relic from
days when we couldn't reliably assign resources.  (I'm not saying we can do
that reliably even today, but I'd rather make it reliable than turn it
off.)

Kvmtool certainly uses it (and generates its own DT, hence why you don't
see it in mainline). Not sure about qemu, though.

QEMU definitely doesn't do proble-only. Is this driver used on real PPC machines too? In that case you also won't see the dt, because it comes with the hardware ;).


Alex