On 31/03/2020 15:12, Sam Bobroff wrote:
> 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.
>
> Fixes: 7f92891778df ("vfio_pci: Add NVIDIA GV100GL [Tesla V100 SXM2] subdriver")
> Signed-off-by: Sam Bobroff <sbobroff@xxxxxxxxxxxxx>
Reviewed-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> ---
> Patch set v2:
> Patch 1/1: vfio-pci/nvlink2: Allow fallback to ibm,mmio-atsd[0]
> - Removed unnecessary warning.
> - Added Fixes tag.
>
> Patch set v1:
> Patch 1/1: vfio-pci/nvlink2: Allow fallback to ibm,mmio-atsd[0]
>
> drivers/vfio/pci/vfio_pci_nvlink2.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci_nvlink2.c b/drivers/vfio/pci/vfio_pci_nvlink2.c
> index f2983f0f84be..ae2af590e501 100644
> --- a/drivers/vfio/pci/vfio_pci_nvlink2.c
> +++ b/drivers/vfio/pci/vfio_pci_nvlink2.c
> @@ -420,8 +420,14 @@ 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;
> + 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)) {
>
--
Alexey
