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authorBjorn Helgaas <bhelgaas@google.com>2019-01-19 20:35:04 +0300
committerBjorn Helgaas <bhelgaas@google.com>2019-01-22 21:56:35 +0300
commit51c48b310183ab6ba5419edfc6a8de889cc04521 (patch)
tree3492cf9bfc81f046cd3259ee48d6d55231086b8a /drivers/pci/setup-bus.c
parentbfeffd155283772bbe78c6a05dec7c0128ee500c (diff)
downloadlinux-51c48b310183ab6ba5419edfc6a8de889cc04521.tar.xz
PCI: Probe bridge window attributes once at enumeration-time
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-wangzhou1@hisilicon.com Link: https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg02082.html Reported-by: Yandong Xu <xuyandong2@huawei.com> Tested-by: Yandong Xu <xuyandong2@huawei.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Ofer Hayut <ofer@lightbitslabs.com> Cc: Roy Shterman <roys@lightbitslabs.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Zhou Wang <wangzhou1@hisilicon.com>
Diffstat (limited to 'drivers/pci/setup-bus.c')
-rw-r--r--drivers/pci/setup-bus.c45
1 files changed, 4 insertions, 41 deletions
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