[PATCH] drm/amdkfd: Allocate doorbells only when needed

[Russell, Kent]

[AMD Official Use Only - General]

I can throw an Acked-by: Kent Russell <kent.russell at amd.com> since we don't have an RB yet.

 Kent

> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Felix
> Kuehling
> Sent: Wednesday, August 3, 2022 2:56 PM
> To: amd-gfx at lists.freedesktop.org
> Subject: [PATCH] drm/amdkfd: Allocate doorbells only when needed
> 
> Only allocate doorbells when the first queue is created on a GPU or the
> doorbells need to be mapped into CPU or GPU virtual address space. This
> avoids allocating doorbells unnecessarily and can allow more processes
> to use KFD on multi-GPU systems.
> 
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_chardev.c  | 13 +++++++++++++
>  drivers/gpu/drm/amd/amdkfd/kfd_doorbell.c |  9 +++++++++
>  drivers/gpu/drm/amd/amdkfd/kfd_process.c  |  5 -----
>  3 files changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> index 2b3d8bc8f0aa..907f4711abce 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> @@ -327,6 +327,12 @@ static int kfd_ioctl_create_queue(struct file *filep,
> struct kfd_process *p,
>  		goto err_bind_process;
>  	}
> 
> +	if (!pdd->doorbell_index &&
> +	    kfd_alloc_process_doorbells(dev, &pdd->doorbell_index) < 0) {
> +		err = -ENOMEM;
> +		goto err_alloc_doorbells;
> +	}
> +
>  	/* Starting with GFX11, wptr BOs must be mapped to GART for MES to
> determine work
>  	 * on unmapped queues for usermode queue oversubscription (no
> aggregated doorbell)
>  	 */
> @@ -404,6 +410,7 @@ static int kfd_ioctl_create_queue(struct file *filep, struct
> kfd_process *p,
>  	if (wptr_bo)
>  		amdgpu_amdkfd_free_gtt_mem(dev->adev, wptr_bo);
>  err_wptr_map_gart:
> +err_alloc_doorbells:
>  err_bind_process:
>  err_pdd:
>  	mutex_unlock(&p->mutex);
> @@ -1092,6 +1099,10 @@ static int kfd_ioctl_alloc_memory_of_gpu(struct file
> *filep,
>  			goto err_unlock;
>  		}
>  		offset = kfd_get_process_doorbells(pdd);
> +		if (!offset) {
> +			err = -ENOMEM;
> +			goto err_unlock;
> +		}
>  	} else if (flags & KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP) {
>  		if (args->size != PAGE_SIZE) {
>  			err = -EINVAL;
> @@ -2173,6 +2184,8 @@ static int criu_restore_memory_of_gpu(struct
> kfd_process_device *pdd,
>  			return -EINVAL;
> 
>  		offset = kfd_get_process_doorbells(pdd);
> +		if (!offset)
> +			return -ENOMEM;
>  	} else if (bo_bucket->alloc_flags &
> KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP) {
>  		/* MMIO BOs need remapped bus address */
>  		if (bo_bucket->size != PAGE_SIZE) {
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_doorbell.c
> b/drivers/gpu/drm/amd/amdkfd/kfd_doorbell.c
> index cb3d2ccc5100..b33798f89ef0 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_doorbell.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_doorbell.c
> @@ -157,6 +157,8 @@ int kfd_doorbell_mmap(struct kfd_dev *dev, struct
> kfd_process *process,
> 
>  	/* Calculate physical address of doorbell */
>  	address = kfd_get_process_doorbells(pdd);
> +	if (!address)
> +		return -ENOMEM;
>  	vma->vm_flags |= VM_IO | VM_DONTCOPY | VM_DONTEXPAND |
> VM_NORESERVE |
>  				VM_DONTDUMP | VM_PFNMAP;
> 
> @@ -275,6 +277,13 @@ uint64_t kfd_get_number_elems(struct kfd_dev *kfd)
> 
>  phys_addr_t kfd_get_process_doorbells(struct kfd_process_device *pdd)
>  {
> +	if (!pdd->doorbell_index) {
> +		int r = kfd_alloc_process_doorbells(pdd->dev,
> +						    &pdd->doorbell_index);
> +		if (r)
> +			return 0;
> +	}
> +
>  	return pdd->dev->doorbell_base +
>  		pdd->doorbell_index * kfd_doorbell_process_slice(pdd->dev);
>  }
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index 6c83a519b3a1..951b63677248 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -1499,11 +1499,6 @@ struct kfd_process_device
> *kfd_create_process_device_data(struct kfd_dev *dev,
>  	if (!pdd)
>  		return NULL;
> 
> -	if (kfd_alloc_process_doorbells(dev, &pdd->doorbell_index) < 0) {
> -		pr_err("Failed to alloc doorbell for pdd\n");
> -		goto err_free_pdd;
> -	}
> -
>  	if (init_doorbell_bitmap(&pdd->qpd, dev)) {
>  		pr_err("Failed to init doorbell for process\n");
>  		goto err_free_pdd;
> --
> 2.32.0