** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Changed in: canonical-kernel-snaps
Status: New => Invalid
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https://bugs.launchpad.net/bugs/2122060
Title:
Please backport 1a596ad00ffe9b37fc60a93cbdd4daead3bf95f3 to 6.8, 6.11
kernels
Status in canonical-kernel-snaps:
Invalid
Status in linux package in Ubuntu:
New
Bug description:
Please backport 1a596ad00ffe9b37fc60a93cbdd4daead3bf95f3 to your 6.8 and 6.11
kernels.
This is generic.
The problem manifested on hardware that was a PCIe bridge that also had a
endpoint (a management interface BAR).
It has impacted customers using yourv6.8 kernel.
author Kai-Heng Feng <[email protected]> 2024-12-04 10:24:57
+0800
committer Bjorn Helgaas <[email protected]> 2025-02-18 14:46:55
-0600
commit 1a596ad00ffe9b37fc60a93cbdd4daead3bf95f3 (patch)
tree 4483304ec3fc0135852eb91f0b9e57fc7bf48063
parent addb30c5bd2755770e617e68bdcc0bf2a21770fa (diff)
download linux-1a596ad00ffe9b37fc60a93cbdd4daead3bf95f3.tar.gz
PCI: Use downstream bridges for distributing resources
7180c1d08639 ("PCI: Distribute available resources for root buses, too")
breaks BAR assignment on some devices:
pci 0006:03:00.0: BAR 0 [mem 0x6300c0000000-0x6300c1ffffff 64bit pref]:
assigned
pci 0006:03:00.1: BAR 0 [mem 0x6300c2000000-0x6300c3ffffff 64bit pref]:
assigned
pci 0006:03:00.2: BAR 0 [mem size 0x00800000 64bit pref]: can't assign; no
space
pci 0006:03:00.0: VF BAR 0 [mem size 0x02000000 64bit pref]: can't assign;
no space
pci 0006:03:00.1: VF BAR 0 [mem size 0x02000000 64bit pref]: can't assign;
no space
The apertures of domain 0006 before 7180c1d08639:
6300c0000000-63ffffffffff : PCI Bus 0006:00
6300c0000000-6300c9ffffff : PCI Bus 0006:01
6300c0000000-6300c9ffffff : PCI Bus 0006:02 # 160MB
6300c0000000-6300c8ffffff : PCI Bus 0006:03 # 144MB
6300c0000000-6300c1ffffff : 0006:03:00.0 # 32MB
6300c2000000-6300c3ffffff : 0006:03:00.1 # 32MB
6300c4000000-6300c47fffff : 0006:03:00.2 # 8MB
6300c4800000-6300c67fffff : 0006:03:00.0 # 32MB
6300c6800000-6300c87fffff : 0006:03:00.1 # 32MB
6300c9000000-6300c9bfffff : PCI Bus 0006:04 # 12MB
6300c9000000-6300c9bfffff : PCI Bus 0006:05 # 12MB
6300c9000000-6300c91fffff : PCI Bus 0006:06 # 2MB
6300c9200000-6300c93fffff : PCI Bus 0006:07 # 2MB
6300c9400000-6300c95fffff : PCI Bus 0006:08 # 2MB
6300c9600000-6300c97fffff : PCI Bus 0006:09 # 2MB
After 7180c1d08639:
6300c0000000-63ffffffffff : PCI Bus 0006:00
6300c0000000-6300c9ffffff : PCI Bus 0006:01
6300c0000000-6300c9ffffff : PCI Bus 0006:02 # 160MB
6300c0000000-6300c43fffff : PCI Bus 0006:03 # 68MB
6300c0000000-6300c1ffffff : 0006:03:00.0 # 32MB
6300c2000000-6300c3ffffff : 0006:03:00.1 # 32MB
--- no space --- : 0006:03:00.2 # 8MB
--- no space --- : 0006:03:00.0 # 32MB
--- no space --- : 0006:03:00.1 # 32MB
6300c4400000-6300c4dfffff : PCI Bus 0006:04 # 10MB
6300c4400000-6300c4dfffff : PCI Bus 0006:05 # 10MB
6300c4400000-6300c45fffff : PCI Bus 0006:06 # 2MB
6300c4600000-6300c47fffff : PCI Bus 0006:07 # 2MB
6300c4800000-6300c49fffff : PCI Bus 0006:08 # 2MB
6300c4a00000-6300c4bfffff : PCI Bus 0006:09 # 2MB
We can see that the window to 0006:03 gets shrunken too much and 0006:04
eats away the window for 0006:03:00.2.
The offending commit distributes the upstream bridge's resources multiple
times to every downstream bridge, hence makes the aperture smaller than
desired because calculation of io_per_b, mmio_per_b and mmio_pref_per_b
becomes incorrect.
Instead, distribute downstream bridges' own resources to resolve the
issue.
Link: https://lore.kernel.org/r/[email protected]
Fixes: 7180c1d08639 ("PCI: Distribute available resources for root buses,
too")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219540
Signed-off-by: Kai-Heng Feng <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Tested-by: Chia-Lin Kao (AceLan) <[email protected]>
Reviewed-by: Mika Westerberg <[email protected]>
Cc: Carol Soto <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Chris Chiu <[email protected]>
Diffstat
-rw-r--r-- drivers/pci/setup-bus.c 3
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 5e00cecf1f1af3..3d876d493faf2d 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -2102,8 +2102,7 @@ pci_root_bus_distribute_available_resources(struct
pci_bus *bus,
* in case of root bus.
*/
if (bridge && pci_bridge_resources_not_assigned(dev))
- pci_bridge_distribute_available_resources(bridge,
- add_list);
+ pci_bridge_distribute_available_resources(dev,
add_list);
else
pci_root_bus_distribute_available_resources(b,
add_list);
}
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