Older versions of skiboot only provide a single value in the device
tree property "ibm,mmio-atsd", even when multiple Address Translation
Shoot Down (ATSD) registers are present. This prevents NVLink2 devices
(other than the first) from being used with vfio-pci because vfio-pci
expects to be able to assign a dedicated ATSD register to each NVLink2
device.
However, ATSD registers can be shared among devices. This change
allows vfio-pci to fall back to sharing the register at index 0 if
necessary.
Signed-off-by: Sam Bobroff <sbobroff@xxxxxxxxxxxxx>
---
drivers/vfio/pci/vfio_pci_nvlink2.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_nvlink2.c b/drivers/vfio/pci/vfio_pci_nvlink2.c
index f2983f0f84be..851ba673882b 100644
--- a/drivers/vfio/pci/vfio_pci_nvlink2.c
+++ b/drivers/vfio/pci/vfio_pci_nvlink2.c
@@ -420,8 +420,17 @@ int vfio_pci_ibm_npu2_init(struct vfio_pci_device *vdev)
if (of_property_read_u64_index(hose->dn, "ibm,mmio-atsd", nvlink_index,
&mmio_atsd)) {
- dev_warn(&vdev->pdev->dev, "No available ATSD found\n");
- mmio_atsd = 0;
+ dev_warn(&vdev->pdev->dev,
+ "No ibm,mmio-atsd[%d] found: trying ibm,mmio-atsd[0]\n",
+ nvlink_index);
+ if (of_property_read_u64_index(hose->dn, "ibm,mmio-atsd", 0,
+ &mmio_atsd)) {
+ dev_warn(&vdev->pdev->dev, "No available ATSD found\n");
+ mmio_atsd = 0;
+ } else {
+ dev_warn(&vdev->pdev->dev,
+ "Using fallback ibm,mmio-atsd[0] for ATSD.\n");
+ }
}
if (of_property_read_u64(npu_node, "ibm,device-tgt-addr", &tgt)) {
--
2.22.0.216.g00a2a96fc9
