linux-kernel - [PATCH 3.16 087/305] PCI: Disable all BAR sizing for devices with non-compliant BARs

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Message-ID: <lsq.1471110171.589808778@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Prarit Bhargava" <prarit@...hat.com>,
	"Ingo Molnar" <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>,
	"Bjorn Helgaas" <bhelgaas@...gle.com>,
	"Andi Kleen" <ak@...ux.intel.com>,
	"Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 3.16 087/305] PCI: Disable all BAR sizing for devices with
 non-compliant BARs

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Prarit Bhargava <prarit@...hat.com>

commit ad67b437f187ea818b2860524d10f878fadfdd99 upstream.

b84106b4e229 ("PCI: Disable IO/MEM decoding for devices with non-compliant
BARs") disabled BAR sizing for BARs 0-5 of devices that don't comply with
the PCI spec.  But it didn't do anything for expansion ROM BARs, so we
still try to size them, resulting in warnings like this on Broadwell-EP:

  pci 0000:ff:12.0: BAR 6: failed to assign [mem size 0x00000001 pref]

Move the non-compliant BAR check from __pci_read_base() up to
pci_read_bases() so it applies to the expansion ROM BAR as well as
to BARs 0-5.

Note that direct callers of __pci_read_base(), like sriov_init(), will now
bypass this check.  We haven't had reports of devices with broken SR-IOV
BARs yet.

[bhelgaas: changelog]
Fixes: b84106b4e229 ("PCI: Disable IO/MEM decoding for devices with non-compliant BARs")
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/pci/probe.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -176,9 +176,6 @@ int __pci_read_base(struct pci_dev *dev,
 	struct pci_bus_region region, inverted_region;
 	bool bar_too_big = false, bar_too_high = false, bar_invalid = false;
 
-	if (dev->non_compliant_bars)
-		return 0;
-
 	mask = type ? PCI_ROM_ADDRESS_MASK : ~0;
 
 	/* No printks while decoding is disabled! */
@@ -330,6 +327,9 @@ static void pci_read_bases(struct pci_de
 {
 	unsigned int pos, reg;
 
+	if (dev->non_compliant_bars)
+		return;
+
 	for (pos = 0; pos < howmany; pos++) {
 		struct resource *res = &dev->resource[pos];
 		reg = PCI_BASE_ADDRESS_0 + (pos << 2);