From: Bjorn Helgaas <bhelg...@google.com> pci_bridge_check_ranges() determines whether a bridge supports the optional I/O and prefetchable memory windows and sets the flag bits in the bridge resources. This *could* be done once during enumeration except that the resource allocation code completely clears the flag bits, e.g., in the pci_assign_unassigned_bridge_resources() path.
The problem with pci_bridge_check_ranges() in the resource allocation path is that we may allocate resources after devices have been claimed by drivers, and pci_bridge_check_ranges() *changes* the window registers to determine whether they're writable. This may break concurrent accesses to devices behind the bridge. Add a new pci_read_bridge_windows() to determine whether a bridge supports the optional windows, call it once during enumeration, remember the results, and change pci_bridge_check_ranges() so it doesn't touch the bridge windows but sets the flag bits based on those remembered results. Link: https://lore.kernel.org/linux-pci/1506151482-113560-1-git-send-email-wangzh...@hisilicon.com Link: https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg02082.html Reported-by: xuyandong <xuyando...@huawei.com> Tested-by: xuyandong <xuyando...@huawei.com> Cc: Sagi Grimberg <s...@grimberg.me> Cc: Ofer Hayut <o...@lightbitslabs.com> Cc: Roy Shterman <r...@lightbitslabs.com> Cc: Keith Busch <keith.bu...@intel.com> Cc: Zhou Wang <wangzh...@hisilicon.com> --- drivers/pci/probe.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/setup-bus.c | 45 ++++------------------------------------- include/linux/pci.h | 3 +++ 3 files changed, 59 insertions(+), 41 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 257b9f6f2ebb..2ef8b954c65a 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -348,6 +348,57 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom) } } +static void pci_read_bridge_windows(struct pci_dev *bridge) +{ + u16 io; + u32 pmem, tmp; + + pci_read_config_word(bridge, PCI_IO_BASE, &io); + if (!io) { + pci_write_config_word(bridge, PCI_IO_BASE, 0xe0f0); + pci_read_config_word(bridge, PCI_IO_BASE, &io); + pci_write_config_word(bridge, PCI_IO_BASE, 0x0); + } + if (io) + bridge->io_window = 1; + + /* + * DECchip 21050 pass 2 errata: the bridge may miss an address + * disconnect boundary by one PCI data phase. Workaround: do not + * use prefetching on this device. + */ + if (bridge->vendor == PCI_VENDOR_ID_DEC && bridge->device == 0x0001) + return; + + pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); + if (!pmem) { + pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, + 0xffe0fff0); + pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); + pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, 0x0); + } + if (!pmem) + return; + + bridge->pref_window = 1; + + if ((pmem & PCI_PREF_RANGE_TYPE_MASK) == PCI_PREF_RANGE_TYPE_64) { + + /* + * Bridge claims to have a 64-bit prefetchable memory + * window; verify that the upper bits are actually + * writable. + */ + pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &pmem); + pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, + 0xffffffff); + pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &tmp); + pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, pmem); + if (tmp) + bridge->pref_64_window = 1; + } +} + static void pci_read_bridge_io(struct pci_bus *child) { struct pci_dev *dev = child->self; @@ -1739,6 +1790,7 @@ int pci_setup_device(struct pci_dev *dev) pci_read_irq(dev); dev->transparent = ((dev->class & 0xff) == 1); pci_read_bases(dev, 2, PCI_ROM_ADDRESS1); + pci_read_bridge_windows(dev); set_pcie_hotplug_bridge(dev); pos = pci_find_capability(dev, PCI_CAP_ID_SSVID); if (pos) { diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index ed960436df5e..1941bb0a6c13 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -735,58 +735,21 @@ int pci_claim_bridge_resource(struct pci_dev *bridge, int i) base/limit registers must be read-only and read as 0. */ static void pci_bridge_check_ranges(struct pci_bus *bus) { - u16 io; - u32 pmem; struct pci_dev *bridge = bus->self; - struct resource *b_res; + struct resource *b_res = &bridge->resource[PCI_BRIDGE_RESOURCES]; - b_res = &bridge->resource[PCI_BRIDGE_RESOURCES]; b_res[1].flags |= IORESOURCE_MEM; - pci_read_config_word(bridge, PCI_IO_BASE, &io); - if (!io) { - pci_write_config_word(bridge, PCI_IO_BASE, 0xe0f0); - pci_read_config_word(bridge, PCI_IO_BASE, &io); - pci_write_config_word(bridge, PCI_IO_BASE, 0x0); - } - if (io) + if (bridge->io_window) b_res[0].flags |= IORESOURCE_IO; - /* DECchip 21050 pass 2 errata: the bridge may miss an address - disconnect boundary by one PCI data phase. - Workaround: do not use prefetching on this device. */ - if (bridge->vendor == PCI_VENDOR_ID_DEC && bridge->device == 0x0001) - return; - - pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); - if (!pmem) { - pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, - 0xffe0fff0); - pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); - pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, 0x0); - } - if (pmem) { + if (bridge->pref_window) { b_res[2].flags |= IORESOURCE_MEM | IORESOURCE_PREFETCH; - if ((pmem & PCI_PREF_RANGE_TYPE_MASK) == - PCI_PREF_RANGE_TYPE_64) { + if (bridge->pref_64_window) { b_res[2].flags |= IORESOURCE_MEM_64; b_res[2].flags |= PCI_PREF_RANGE_TYPE_64; } } - - /* double check if bridge does support 64 bit pref */ - if (b_res[2].flags & IORESOURCE_MEM_64) { - u32 mem_base_hi, tmp; - pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, - &mem_base_hi); - pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, - 0xffffffff); - pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &tmp); - if (!tmp) - b_res[2].flags &= ~IORESOURCE_MEM_64; - pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, - mem_base_hi); - } } /* Helper function for sizing routines: find first available diff --git a/include/linux/pci.h b/include/linux/pci.h index 65f1d8c2f082..40b327b814aa 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -373,6 +373,9 @@ struct pci_dev { bool match_driver; /* Skip attaching driver */ unsigned int transparent:1; /* Subtractive decode bridge */ + unsigned int io_window:1; /* Bridge has I/O window */ + unsigned int pref_window:1; /* Bridge has pref mem window */ + unsigned int pref_64_window:1; /* Pref mem window is 64-bit */ unsigned int multifunction:1; /* Multi-function device */ unsigned int is_busmaster:1; /* Is busmaster */
