On 11/3/2022 1:14 PM, francisco.munoz.ruiz@xxxxxxxxxxxxxxx wrote:
> 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);
>
> /*
Hi,
Just a gentle reminder for this one
Best wishes,
Francisco.
