[PATCH] drm/amdkfd: clamp queue size to minimum

[Philip Yang]

On 2025-02-25 21:41, David Yat Sin wrote:
> If queue size is less than minimum, clamp it to minimum to prevent
> underflow when writing queue mqd.
>
> Signed-off-by: David Yat Sin <David.YatSin at amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 4 ++++
>   include/uapi/linux/kfd_ioctl.h           | 2 ++
>   2 files changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> index 433de9e9a77e..e90c3d1c8f8a 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> @@ -212,6 +212,8 @@ static int set_queue_properties_from_user(struct queue_properties *q_properties,
>   		return -EINVAL;
>   	}
>   
> +	args->ring_size = max(args->ring_size, KFD_MIN_QUEUE_RING_SIZE);
> +
>   	if (!access_ok((const void __user *) args->read_pointer_address,
>   			sizeof(uint32_t))) {
>   		pr_err("Can't access read pointer\n");
> @@ -461,6 +463,8 @@ static int kfd_ioctl_update_queue(struct file *filp, struct kfd_process *p,
>   		return -EINVAL;
>   	}
>   
> +	args->ring_size = max(args->ring_size, KFD_MIN_QUEUE_RING_SIZE);
> +
>   	properties.queue_address = args->ring_base_address;
>   	properties.queue_size = args->ring_size;
>   	properties.queue_percent = args->queue_percentage & 0xFF;
> diff --git a/include/uapi/linux/kfd_ioctl.h b/include/uapi/linux/kfd_ioctl.h
> index fa9f9846b88e..b0160b09987c 100644
> --- a/include/uapi/linux/kfd_ioctl.h
> +++ b/include/uapi/linux/kfd_ioctl.h
> @@ -62,6 +62,8 @@ struct kfd_ioctl_get_version_args {
>   #define KFD_MAX_QUEUE_PERCENTAGE	100
>   #define KFD_MAX_QUEUE_PRIORITY		15
>   
> +#define KFD_MIN_QUEUE_RING_SIZE		1024
> +

Maybe set to 4096, because hsaKmtAllocMemory and hsaKmtMapMemoryToGPU 
requires page_align size, it is impossible to use 1KB ring buffer.

This can pass user queue validation now because we skip the ring_bo size 
checking as (expected_size >> AMDGPU_GPU_PAGE_SHIFT) is 0.

Regards,

Philip

>   struct kfd_ioctl_create_queue_args {
>   	__u64 ring_base_address;	/* to KFD */
>   	__u64 write_pointer_address;	/* from KFD */