This is a note to let you know that I've just added the patch titled
PCI: Disable IO/MEM decoding for devices with non-compliant BARs
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-disable-io-mem-decoding-for-devices-with-non-compliant-bars.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b84106b4e2290c081cdab521fa832596cdfea246 Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Date: Thu, 25 Feb 2016 14:35:57 -0600
Subject: PCI: Disable IO/MEM decoding for devices with non-compliant BARs
From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
commit b84106b4e2290c081cdab521fa832596cdfea246 upstream.
The PCI config header (first 64 bytes of each device's config space) is
defined by the PCI spec so generic software can identify the device and
manage its usage of I/O, memory, and IRQ resources.
Some non-spec-compliant devices put registers other than BARs where the
BARs should be. When the PCI core sizes these "BARs", the reads and writes
it does may have unwanted side effects, and the "BAR" may appear to
describe non-sensical address space.
Add a flag bit to mark non-compliant devices so we don't touch their BARs.
Turn off IO/MEM decoding to prevent the devices from consuming address
space, since we can't read the BARs to find out what that address space
would be.
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Tested-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/probe.c | 14 ++++++++++++++
include/linux/pci.h | 1 +
2 files changed, 15 insertions(+)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -179,6 +179,9 @@ int __pci_read_base(struct pci_dev *dev,
u16 orig_cmd;
struct pci_bus_region region, inverted_region;
+ if (dev->non_compliant_bars)
+ return 0;
+
mask = type ? PCI_ROM_ADDRESS_MASK : ~0;
/* No printks while decoding is disabled! */
@@ -1174,6 +1177,7 @@ void pci_msi_setup_pci_dev(struct pci_de
int pci_setup_device(struct pci_dev *dev)
{
u32 class;
+ u16 cmd;
u8 hdr_type;
int pos = 0;
struct pci_bus_region region;
@@ -1219,6 +1223,16 @@ int pci_setup_device(struct pci_dev *dev
/* device class may be changed after fixup */
class = dev->class >> 8;
+ if (dev->non_compliant_bars) {
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
+ dev_info(&dev->dev, "device has non-compliant BARs; disabling IO/MEM decoding\n");
+ cmd &= ~PCI_COMMAND_IO;
+ cmd &= ~PCI_COMMAND_MEMORY;
+ pci_write_config_word(dev, PCI_COMMAND, cmd);
+ }
+ }
+
switch (dev->hdr_type) { /* header type */
case PCI_HEADER_TYPE_NORMAL: /* standard header */
if (class == PCI_CLASS_BRIDGE_PCI)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -359,6 +359,7 @@ struct pci_dev {
unsigned int io_window_1k:1; /* Intel P2P bridge 1K I/O windows */
unsigned int irq_managed:1;
unsigned int has_secondary_link:1;
+ unsigned int non_compliant_bars:1; /* broken BARs; ignore them */
pci_dev_flags_t dev_flags;
atomic_t enable_cnt; /* pci_enable_device has been called */
Patches currently in stable-queue which might be from bhelgaas@xxxxxxxxxx are
queue-4.4/x86-pci-mark-broadwell-ep-home-agent-pcu-as-having-non-compliant-bars.patch
queue-4.4/pci-disable-io-mem-decoding-for-devices-with-non-compliant-bars.patch
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