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 guest reboots are performed. Commit id
6aab5622296b ("PCI: vmd: Clean up domain before enumeration") 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>
Reviewed-by: Jonathan Derrick <jonathan.derrick@xxxxxxxxx>
---
V3:
- Add WARN_ON
- Include Jonathan as reviewer
- Update commit message
V2:
- Update commit message
drivers/pci/controller/vmd.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index e06e9f4fc50f..2406be6644f3 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -859,8 +859,17 @@ 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)) {
+ ret = pci_reset_bus(list_first_entry(&child->devices,
+ struct pci_dev,
+ bus_list));
+ WARN_ON(ret);
+ break;
+ }
+ }
+
pci_assign_unassigned_bus_resources(vmd->bus);
/*
--
2.25.1
