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authorBjorn Helgaas <bhelgaas@google.com>2019-01-19 18:35:04 +0100
committerBjorn Helgaas <bhelgaas@google.com>2019-01-22 19:56:35 +0100
commit51c48b310183ab6ba5419edfc6a8de889cc04521 (patch)
tree3492cf9bfc81f046cd3259ee48d6d55231086b8a /drivers/pci/probe.c
parentLinux 5.0-rc1 (diff)
downloadlinux-51c48b310183ab6ba5419edfc6a8de889cc04521.tar.xz
linux-51c48b310183ab6ba5419edfc6a8de889cc04521.zip
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/probe.c')
-rw-r--r--drivers/pci/probe.c52
1 files changed, 52 insertions, 0 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) {