[PATCH] drm/amdkfd: fix no atomics settings in the kfd topology

[Felix Kuehling]

Am 2021-05-03 um 11:57 a.m. schrieb Jonathan Kim:
> To account for various PCIe and xGMI setups, check the no atomics settings
> for a device in relation to every direct peer.

Thanks, this looks reasonable. Some more nit-picks about naming and
coding style inline.


>
> Signed-off-by: Jonathan Kim <jonathan.kim at amd.com>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_topology.c | 55 ++++++++++++++---------
>  1 file changed, 34 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> index 30430aefcfc7..40ac7fe2a499 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
> @@ -1192,47 +1192,60 @@ static void kfd_fill_mem_clk_max_info(struct kfd_topology_device *dev)
>  		mem->mem_clk_max = local_mem_info.mem_clk_max;
>  }
>  
> -static void kfd_fill_iolink_non_crat_info(struct kfd_topology_device *dev)
> +static void kfd_set_iolink_no_atomics(struct kfd_topology_device *dev,
> +					struct kfd_topology_device *target_gpu_dev,
> +					struct kfd_iolink_properties *link)
>  {
> -	struct kfd_iolink_properties *link, *cpu_link;
> -	struct kfd_topology_device *cpu_dev;
> -	struct amdgpu_device *adev;
> -	uint32_t cap;
> -	uint32_t cpu_flag = CRAT_IOLINK_FLAGS_ENABLED;
> -	uint32_t flag = CRAT_IOLINK_FLAGS_ENABLED;
> -
> -	if (!dev || !dev->gpu)
> +	/* xgmi always supports atomics between links. */
> +	if (link->iolink_type == CRAT_IOLINK_TYPE_XGMI)
>  		return;
>  
> -	adev = (struct amdgpu_device *)(dev->gpu->kgd);
> -	if (!adev->gmc.xgmi.connected_to_cpu) {
> -		pcie_capability_read_dword(dev->gpu->pdev,
> +	/* check pcie support to set cpu(dev) flags for target_get_dev link. */
> +	if (target_gpu_dev) {
> +		uint32_t cap;
> +
> +		pcie_capability_read_dword(target_gpu_dev->gpu->pdev,
>  				PCI_EXP_DEVCAP2, &cap);
>  
>  		if (!(cap & (PCI_EXP_DEVCAP2_ATOMIC_COMP32 |
>  			     PCI_EXP_DEVCAP2_ATOMIC_COMP64)))
> -			cpu_flag |= CRAT_IOLINK_FLAGS_NO_ATOMICS_32_BIT |
> +			link->flags |= CRAT_IOLINK_FLAGS_NO_ATOMICS_32_BIT |
>  				CRAT_IOLINK_FLAGS_NO_ATOMICS_64_BIT;
> -	}
> -
> -	if (!adev->gmc.xgmi.num_physical_nodes) {
> +	/* set gpu (dev) flags. */
> +	} else {
>  		if (!dev->gpu->pci_atomic_requested ||
>  				dev->gpu->device_info->asic_family ==
>  							CHIP_HAWAII)
> -			flag |= CRAT_IOLINK_FLAGS_NO_ATOMICS_32_BIT |
> +			link->flags |= CRAT_IOLINK_FLAGS_NO_ATOMICS_32_BIT |
>  				CRAT_IOLINK_FLAGS_NO_ATOMICS_64_BIT;
>  	}
> +}
> +
> +static void kfd_fill_iolink_non_crat_info(struct kfd_topology_device *dev)
> +{
> +	struct kfd_iolink_properties *link, *cpu_link;
> +	struct kfd_topology_device *cpu_dev;

The names cpu_link and cpu_dev are still misleading. When GPUs have XGMI
links these links may, in fact, be other GPUs and the XGMI links from
those GPUs. I think a better name would be "peer_dev" and "inbound_link".


> +	uint32_t flag_enable = CRAT_IOLINK_FLAGS_ENABLED;

You don't need this variable. Just use CRAT_IOLINK_FLAGS_ENABLED below.


> +
> +	if (!dev || !dev->gpu)
> +		return;
>  
>  	/* GPU only creates direct links so apply flags setting to all */
>  	list_for_each_entry(link, &dev->io_link_props, list) {
> -		link->flags = flag;
> +		link->flags = flag_enable;
> +		kfd_set_iolink_no_atomics(dev, NULL, link);
>  		cpu_dev = kfd_topology_device_by_proximity_domain(
>  				link->node_to);
> +
>  		if (cpu_dev) {

To minimize indentation, I'd do

	if (!peer_dev)
		continue;

>  			list_for_each_entry(cpu_link,
> -					    &cpu_dev->io_link_props, list)
> -				if (cpu_link->node_to == link->node_from)
> -					cpu_link->flags = cpu_flag;
> +					    &cpu_dev->io_link_props, list) {
> +				if (cpu_link->node_to == link->node_from) {
> +					cpu_link->flags = flag_enable;

To minimize indentation, and to avoid unnecessary loop iterations, I'd do

	if (inbound_link->node_to != link->node_from)
		continue;
	inbound_link->flags = KFD_IOLINK_CRAT_FLAGS_ENABLED;
	kfd_set_iolink_no_atomics(peer_dev, dev, inbound_link);
	break;

Regards,
  Felix


> +					kfd_set_iolink_no_atomics(cpu_dev, dev,
> +								cpu_link);
> +				}
> +			}
>  		}
>  	}
>  }