PCI: Disable IO/MEM decoding for devices with non-compliant BARs

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@google.com>
Tested-by: Andi Kleen <ak@linux.intel.com>
CC: stable@vger.kernel.org

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 6d7ab9bb0d5a6f002debd5a3b83e569f78c44c96..6b0056e9c33e0c092cdcf4411c1ceb1e7ef0e177 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -179,6 +179,9 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
        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! */
@@ -1171,6 +1174,7 @@ static void pci_msi_setup_pci_dev(struct pci_dev *dev)
 int pci_setup_device(struct pci_dev *dev)
 {
        u32 class;
+       u16 cmd;
        u8 hdr_type;
        int pos = 0;
        struct pci_bus_region region;
@@ -1214,6 +1218,16 @@ 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)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 27df4a6585daedcc6a74865bf048cfd06a0593ba..5f80661d351901c0f75de27617950cb63ab2f966 100644 (file)
--- 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 */