OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

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>
This commit is contained in:
Bjorn Helgaas 2019-01-19 11:35:04 -06:00
parent bfeffd1552
commit 51c48b3101
3 changed files with 59 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
drivers/pci/probe.c
View File

@ -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) {

45
drivers/pci/setup-bus.c
View File

@ -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

3
include/linux/pci.h
View File

@ -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 */