From: Francisco Munoz <francisco.munoz.ruiz@xxxxxxxxxxxxxxx>
The reset was never applied in the current implementation because Intel
Bridges owned by VMD are parentless. Internally, pci_reset_bus applies
a reset to the parent of the pci device supplied as argument, but in this
case it failed because there wasn't a parent.
In more detail, this change allows the VMD driver to enumerate NVMe devices
in pass-through configurations when host reboots are performed. Commit id
“6aab5622296b990024ee67dd7efa7d143e7558d0” attempted to fix this, but
later we discovered that the code inside pci_reset_bus wasn’t triggering
secondary bus resets. Therefore, we updated the parameters passed to
it, and now NVMe SSDs attached to VMD bridges are properly enumerated in
VT-d pass-through scenarios.
Signed-off-by: Francisco Munoz <francisco.munoz.ruiz@xxxxxxxxxxxxxxx>
Reviewed-by: Nirmal Patel <nirmal.patel@xxxxxxxxxxxxxxx>
---
drivers/pci/controller/vmd.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index e06e9f4fc50f..34d6ba675440 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -859,8 +859,16 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
pci_scan_child_bus(vmd->bus);
vmd_domain_reset(vmd);
- list_for_each_entry(child, &vmd->bus->children, node)
- pci_reset_bus(child->self);
+
+ list_for_each_entry(child, &vmd->bus->children, node) {
+ if (!list_empty(&child->devices)) {
+ pci_reset_bus(list_first_entry(&child->devices,
+ struct pci_dev,
+ bus_list));
+ break;
+ }
+ }
+
pci_assign_unassigned_bus_resources(vmd->bus);
/*
--
2.25.1
Hi Bjorn,
I updated the commit message with more details. Hopefully, this will
clarify its purpose.
Thanks,
Francisco.
