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

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@google.com>
Tested-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 5b428db6a150106a322fbb5a07052ac06a0ff9b1..146b1375257236299737a9353490e9195f69047a 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -175,6 +175,9 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
        struct pci_bus_region region, inverted_region;
        bool bar_too_big = false, bar_disabled = false;
 
+       if (dev->non_compliant_bars)
+               return 0;
+
        mask = type ? PCI_ROM_ADDRESS_MASK : ~0;
 
        /* No printks while decoding is disabled! */
@@ -1074,6 +1077,7 @@ int pci_cfg_space_size(struct pci_dev *dev)
 int pci_setup_device(struct pci_dev *dev)
 {
        u32 class;
+       u16 cmd;
        u8 hdr_type;
        struct pci_slot *slot;
        int pos = 0;
@@ -1121,6 +1125,16 @@ 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 d662546f77d83fc6f13c02dec68c1070cc91c0f2..ecc6e129faa971aca9db4e4e9d86a46dca932f00 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -344,6 +344,7 @@ struct pci_dev {
        unsigned int    __aer_firmware_first:1;
        unsigned int    broken_intx_masking:1;
        unsigned int    io_window_1k:1; /* Intel P2P bridge 1K I/O windows */
+       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 */