On 2024/11/28 5:45 PM, Mika Westerberg wrote:
External email: Use caution opening links or attachments
On Thu, Nov 28, 2024 at 04:40:39PM +0800, Kai-Heng Feng wrote:
Commit 7180c1d08639 ("PCI: Distribute available resources for root
buses, too") breaks BAR assignment on some devcies:
[ 10.021193] pci 0006:03:00.0: BAR 0 [mem 0x6300c0000000-0x6300c1ffffff 64bit pref]: assigned
[ 10.029880] pci 0006:03:00.1: BAR 0 [mem 0x6300c2000000-0x6300c3ffffff 64bit pref]: assigned
[ 10.038561] pci 0006:03:00.2: BAR 0 [mem size 0x00800000 64bit pref]: can't assign; no space
[ 10.047191] pci 0006:03:00.2: BAR 0 [mem size 0x00800000 64bit pref]: failed to assign
[ 10.055285] pci 0006:03:00.0: VF BAR 0 [mem size 0x02000000 64bit pref]: can't assign; no space
[ 10.064180] pci 0006:03:00.0: VF BAR 0 [mem size 0x02000000 64bit pref]: failed to assign
[ 10.072543] pci 0006:03:00.1: VF BAR 0 [mem size 0x02000000 64bit pref]: can't assign; no space
[ 10.081437] pci 0006:03:00.1: VF BAR 0 [mem size 0x02000000 64bit pref]: failed to assign
The apertures of domain 0006 before the commit:
6300c0000000-63ffffffffff : PCI Bus 0006:00
6300c0000000-6300c9ffffff : PCI Bus 0006:01
6300c0000000-6300c9ffffff : PCI Bus 0006:02
6300c0000000-6300c8ffffff : PCI Bus 0006:03
6300c0000000-6300c1ffffff : 0006:03:00.0
6300c0000000-6300c1ffffff : mlx5_core
6300c2000000-6300c3ffffff : 0006:03:00.1
6300c2000000-6300c3ffffff : mlx5_core
6300c4000000-6300c47fffff : 0006:03:00.2
6300c4800000-6300c67fffff : 0006:03:00.0
6300c6800000-6300c87fffff : 0006:03:00.1
6300c9000000-6300c9bfffff : PCI Bus 0006:04
6300c9000000-6300c9bfffff : PCI Bus 0006:05
6300c9000000-6300c91fffff : PCI Bus 0006:06
6300c9200000-6300c93fffff : PCI Bus 0006:07
6300c9400000-6300c95fffff : PCI Bus 0006:08
6300c9600000-6300c97fffff : PCI Bus 0006:09
After the commit:
6300c0000000-63ffffffffff : PCI Bus 0006:00
6300c0000000-6300c9ffffff : PCI Bus 0006:01
6300c0000000-6300c9ffffff : PCI Bus 0006:02
6300c0000000-6300c43fffff : PCI Bus 0006:03
6300c0000000-6300c1ffffff : 0006:03:00.0
6300c0000000-6300c1ffffff : mlx5_core
6300c2000000-6300c3ffffff : 0006:03:00.1
6300c2000000-6300c3ffffff : mlx5_core
6300c4400000-6300c4dfffff : PCI Bus 0006:04
6300c4400000-6300c4dfffff : PCI Bus 0006:05
6300c4400000-6300c45fffff : PCI Bus 0006:06
6300c4600000-6300c47fffff : PCI Bus 0006:07
6300c4800000-6300c49fffff : PCI Bus 0006:08
6300c4a00000-6300c4bfffff : PCI Bus 0006:09
We can see that the window of 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 bridges, hence makes the aperture
smaller than desired because calculation of io_per_b, mmio_per_b and
mmio_pref_per_b becomes incorrect.
Instead, distributing downstream bridges' own resources to resolve the
issue.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219540
Cc: Carol Soto <csoto@xxxxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Chris Chiu <chris.chiu@xxxxxxxxxxxxx>
Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Reviewed-by: Matthew R. Ochs <mochs@xxxxxxxxxx>
Reviewed-by: Koba Ko <kobak@xxxxxxxxxx>
Fixes: 7180c1d08639 ("PCI: Distribute available resources for root buses, too")
Signed-off-by: Kai-Heng Feng <kaihengf@xxxxxxxxxx>
---
drivers/pci/setup-bus.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 23082bc0ca37..2db19c17e824 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -2105,7 +2105,7 @@ pci_root_bus_distribute_available_resources(struct pci_bus *bus,
* in case of root bukjijs.
*/
if (bridge && pci_bridge_resources_not_assigned(dev))
- pci_bridge_distribute_available_resources(bridge,
+ pci_bridge_distribute_available_resources(dev,
add_list);
I think it looks better if you put this into one line instead:
pci_bridge_distribute_available_resources(dev, add_list);
Sure, will do.
Otherwise looks good. I wonder if you checked that this still works with
the cases 7180c1d08639 tried to solve? ;-)
That's why Chris is Cc'ed.
Chris, is it possible to give this patch a try to make sure this doesn't break
what 7180c1d08639 solved?
Will send v2 after your test result.
Kai-Heng
else
pci_root_bus_distribute_available_resources(b, add_list);
--
2.47.0
