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

[ Upstream commit b84106b4e2290c081cdab521fa832596cdfea246 ]

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
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index b326a13dcb776c634c16295915cbe41a74bf94e9..3f2d424c723fd9f965786c1ce61f1c7bf666f969 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -177,6 +177,9 @@ 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_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! */
@@ -1128,6 +1131,7 @@ 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;
@@ -1175,6 +1179,16 @@ 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 e54f11655590184555da5350c6f3fa247b150e0e..88f1faf3de43993ffeda8efd10dbd74a3ef8caf6 100644 (file)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -357,6 +357,7 @@ 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 */