Commit 3ed181b8 authored by Harish Kasiviswanathan's avatar Harish Kasiviswanathan Committed by Alex Deucher
Browse files

drm/amdkfd: Ensure gpu_id is unique 



gpu_id needs to be unique for user space to identify GPUs via KFD
interface. In the current implementation there is a very small
probability of having non unique gpu_ids.

v2: Add check to confirm if gpu_id is unique. If not unique, find one
    Changed commit header to reflect the above
v3: Use crc16 as suggested-by: Lijo Lazar <lijo.lazar@amd.com>
    Ensure that gpu_id != 0

Signed-off-by: default avatarHarish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>
Reviewed-by: default avatarLijo Lazar <lijo.lazar@amd.com>
Reviewed-by: default avatarFelix Kuehling <felix.kuehling@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent b712d7c2

drivers/gpu/drm/amd/amdkfd/kfd_topology.c

+34 −6
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/log2.h>

#include <linux/dmi.h>

#include <linux/atomic.h>

#include <linux/crc16.h>



#include "kfd_priv.h"

#include "kfd_crat.h"
@@ -1091,14 +1092,17 @@ void kfd_topology_shutdown(void) 


static uint32_t kfd_generate_gpu_id(struct kfd_node *gpu)

{

	uint32_t hashout;

	uint32_t gpu_id;

	uint32_t buf[8];

	uint64_t local_mem_size;

	int i;

	struct kfd_topology_device *dev;

	bool is_unique;

	uint8_t *crc_buf;



	if (!gpu)

		return 0;



	crc_buf = (uint8_t *)&buf;

	local_mem_size = gpu->local_mem_info.local_mem_size_private +

			gpu->local_mem_info.local_mem_size_public;

	buf[0] = gpu->adev->pdev->devfn;
@@ -1111,10 +1115,34 @@ static uint32_t kfd_generate_gpu_id(struct kfd_node *gpu) 
	buf[6] = upper_32_bits(local_mem_size);

	buf[7] = (ffs(gpu->xcc_mask) - 1) | (NUM_XCC(gpu->xcc_mask) << 16);



	for (i = 0, hashout = 0; i < 8; i++)

		hashout ^= hash_32(buf[i], KFD_GPU_ID_HASH_WIDTH);

	gpu_id = crc16(0, crc_buf, sizeof(buf)) &

		 ((1 << KFD_GPU_ID_HASH_WIDTH) - 1);



	/* There is a very small possibility when generating a

	 * 16 (KFD_GPU_ID_HASH_WIDTH) bit value from 8 word buffer

	 * that the value could be 0 or non-unique. So, check if

	 * it is unique and non-zero. If not unique increment till

	 * unique one is found. In case of overflow, restart from 1

	 */



	down_read(&topology_lock);

	do {

		is_unique = true;

		if (!gpu_id)

			gpu_id = 1;

		list_for_each_entry(dev, &topology_device_list, list) {

			if (dev->gpu && dev->gpu_id == gpu_id) {

				is_unique = false;

				break;

			}

		}

		if (unlikely(!is_unique))

			gpu_id = (gpu_id + 1) &

				  ((1 << KFD_GPU_ID_HASH_WIDTH) - 1);

	} while (!is_unique);

	up_read(&topology_lock);



	return hashout;

	return gpu_id;

}

/* kfd_assign_gpu - Attach @gpu to the correct kfd topology device. If

 *		the GPU device is not already present in the topology device
@@ -1945,7 +1973,6 @@ int kfd_topology_add_device(struct kfd_node *gpu) 
	struct amdgpu_gfx_config *gfx_info = &gpu->adev->gfx.config;

	struct amdgpu_cu_info *cu_info = &gpu->adev->gfx.cu_info;



	gpu_id = kfd_generate_gpu_id(gpu);

	if (gpu->xcp && !gpu->xcp->ddev) {

		dev_warn(gpu->adev->dev,

			 "Won't add GPU to topology since it has no drm node assigned.");
@@ -1968,6 +1995,7 @@ int kfd_topology_add_device(struct kfd_node *gpu) 
	if (res)

		return res;



	gpu_id = kfd_generate_gpu_id(gpu);

	dev->gpu_id = gpu_id;

	gpu->id = gpu_id;