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| author | Bjorn Helgaas <bhelgaas@google.com> | 2019-01-19 11:35:04 -0600 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2019-01-22 12:56:35 -0600 |
| commit | 51c48b310183ab6ba5419edfc6a8de889cc04521 (patch) | |
| tree | 3492cf9bfc81f046cd3259ee48d6d55231086b8a /include/linux/pci.h | |
| parent | bfeffd155283772bbe78c6a05dec7c0128ee500c (diff) | |
| download | lwn-51c48b310183ab6ba5419edfc6a8de889cc04521.tar.gz lwn-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 'include/linux/pci.h')
| -rw-r--r-- | include/linux/pci.h | 3 |
1 files changed, 3 insertions, 0 deletions
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 */ |