linux-kernel - [PATCH 2/2] PCI: Resources outside their window must set IORESOURCE

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Message-Id: <20250924134228.1663-3-ilpo.jarvinen@linux.intel.com>
Date: Wed, 24 Sep 2025 16:42:28 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: linux-pci@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Krzysztof Wilczyński <kw@...ux.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	linux-kernel@...r.kernel.org
Cc: Lucas De Marchi <lucas.demarchi@...el.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 2/2] PCI: Resources outside their window must set IORESOURCE_UNSET

PNP resources are checked for conflicts with the other resource in the
system by quirk_system_pci_resources() that walks through all PCI
resources. quirk_system_pci_resources() correctly filters out resource
with IORESOURCE_UNSET.

Resources that do not reside within their bridge window, however, are
not properly initialized with IORESOURCE_UNSET resulting in bogus
conflicts detected in quirk_system_pci_resources():

pci 0000:00:02.0: VF BAR 2 [mem 0x00000000-0x1fffffff 64bit pref]
pci 0000:00:02.0: VF BAR 2 [mem 0x00000000-0xdfffffff 64bit pref]: contains BAR 2 for 7 VFs
...
pci 0000:03:00.0: VF BAR 2 [mem 0x00000000-0x1ffffffff 64bit pref]
pci 0000:03:00.0: VF BAR 2 [mem 0x00000000-0x3dffffffff 64bit pref]: contains BAR 2 for 31 VFs
...
pnp 00:04: disabling [mem 0xfc000000-0xfc00ffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xc0000000-0xcfffffff] because it overlaps 0000:00:02.0 BAR 9 [mem 0x00000000-0xdfffffff 64bit pref]
pnp 00:05: disabling [mem 0xfedc0000-0xfedc7fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xfeda0000-0xfeda0fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xfeda1000-0xfeda1fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xc0000000-0xcfffffff disabled] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xfed20000-0xfed7ffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xfed90000-0xfed93fff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xfed45000-0xfed8ffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]
pnp 00:05: disabling [mem 0xfee00000-0xfeefffff] because it overlaps 0000:03:00.0 BAR 9 [mem 0x00000000-0x3dffffffff 64bit pref]

Mark resources that are not contained within their bridge window with
IORESOURCE_UNSET in __pci_read_base() which resolves the false
positives for the overlap check in quirk_system_pci_resources().

Fixes: f7834c092c42 ("PNP: Don't check for overlaps with unassigned PCI BARs")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---

This change uses resource_contains() which will reject partial overlaps.
I don't know for sure if partial overlaps should be allowed or not (but
they feel as something FW didn't set things up properly so I chose to
mark them UNSET as well).

 drivers/pci/probe.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 7f9da8c41620..097389f25853 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -205,6 +205,26 @@ static void __pci_size_rom(struct pci_dev *dev, unsigned int pos, u32 *sizes)
 	__pci_size_bars(dev, 1, pos, sizes, true);
 }
 
+static struct resource *pbus_select_window_for_res_addr(
+					const struct pci_bus *bus,
+					const struct resource *res)
+{
+	unsigned long type = res->flags & IORESOURCE_TYPE_BITS;
+	struct resource *r;
+
+	pci_bus_for_each_resource(bus, r) {
+		if (!r || r == &ioport_resource || r == &iomem_resource)
+			continue;
+
+		if ((r->flags & IORESOURCE_TYPE_BITS) != type)
+			continue;
+
+		if (resource_contains(r, res))
+			return r;
+	}
+	return NULL;
+}
+
 /**
  * __pci_read_base - Read a PCI BAR
  * @dev: the PCI device
@@ -329,6 +349,18 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 			 res_name, (unsigned long long)region.start);
 	}
 
+	if (!(res->flags & IORESOURCE_UNSET)) {
+		struct resource *b_res;
+
+		b_res = pbus_select_window_for_res_addr(dev->bus, res);
+		if (!b_res ||
+		    b_res->flags & (IORESOURCE_UNSET | IORESOURCE_DISABLED)) {
+			pci_dbg(dev, "%s %pR: no initial claim (no window)\n",
+				res_name, res);
+			res->flags |= IORESOURCE_UNSET;
+		}
+	}
+
 	goto out;
 
 
-- 
2.39.5