[PATCH] drm/amdkfd: Simplify the mmap offset related bit operations

[Kuehling, Felix]

On 2019-11-01 4:48 p.m., Zhao, Yong wrote:
> The new code is much cleaner and results in better readability.
>
> Change-Id: I0c1f7cca7e24ddb7b4ffe1cb0fa71943828ae373
> Signed-off-by: Yong Zhao <Yong.Zhao at amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 13 +++++++------
>   drivers/gpu/drm/amd/amdkfd/kfd_events.c  |  1 -
>   drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |  9 +++------
>   drivers/gpu/drm/amd/amdkfd/kfd_process.c |  3 +--
>   4 files changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> index b91993753b82..590138727ca9 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
> @@ -298,7 +298,6 @@ static int kfd_ioctl_create_queue(struct file *filep, struct kfd_process *p,
>   	/* Return gpu_id as doorbell offset for mmap usage */
>   	args->doorbell_offset = KFD_MMAP_TYPE_DOORBELL;
>   	args->doorbell_offset |= KFD_MMAP_GPU_ID(args->gpu_id);
> -	args->doorbell_offset <<= PAGE_SHIFT;
>   	if (KFD_IS_SOC15(dev->device_info->asic_family))
>   		/* On SOC15 ASICs, include the doorbell offset within the
>   		 * process doorbell frame, which could be 1 page or 2 pages.
> @@ -1938,20 +1937,22 @@ static int kfd_mmap(struct file *filp, struct vm_area_struct *vma)
>   {
>   	struct kfd_process *process;
>   	struct kfd_dev *dev = NULL;
> -	unsigned long vm_pgoff;
> +	unsigned long mmap_offset;
>   	unsigned int gpu_id;
>   
>   	process = kfd_get_process(current);
>   	if (IS_ERR(process))
>   		return PTR_ERR(process);
>   
> -	vm_pgoff = vma->vm_pgoff;
> -	vma->vm_pgoff = KFD_MMAP_OFFSET_VALUE_GET(vm_pgoff);
> -	gpu_id = KFD_MMAP_GPU_ID_GET(vm_pgoff);
> +	mmap_offset = vma->vm_pgoff << PAGE_SHIFT;
> +	gpu_id = KFD_MMAP_GET_GPU_ID(mmap_offset);
>   	if (gpu_id)
>   		dev = kfd_device_by_id(gpu_id);
>   
> -	switch (vm_pgoff & KFD_MMAP_TYPE_MASK) {
> +	/* only leave the offset segment */
> +	vma->vm_pgoff &= (1ULL << (KFD_MMAP_GPU_ID_SHIFT - PAGE_SHIFT)) - 1;

You're now open-coding what used to be done by the 
KFD_MMAP_OFFSET_VALUE_GET macro. I don't see how this is an improvement. 
Maybe better to update the macro to do this.


> +
> +	switch (mmap_offset & KFD_MMAP_TYPE_MASK) {
>   	case KFD_MMAP_TYPE_DOORBELL:
>   		if (!dev)
>   			return -ENODEV;
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> index 908081c85de1..1f8365575b12 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> @@ -346,7 +346,6 @@ int kfd_event_create(struct file *devkfd, struct kfd_process *p,
>   		ret = create_signal_event(devkfd, p, ev);
>   		if (!ret) {
>   			*event_page_offset = KFD_MMAP_TYPE_EVENTS;
> -			*event_page_offset <<= PAGE_SHIFT;
>   			*event_slot_index = ev->event_id;
>   		}
>   		break;
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> index 66bae8f2dad1..8eecd2cd1fd2 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
> @@ -59,24 +59,21 @@
>    * NOTE: struct vm_area_struct.vm_pgoff uses offset in pages. Hence, these
>    *  defines are w.r.t to PAGE_SIZE
>    */
> -#define KFD_MMAP_TYPE_SHIFT	(62 - PAGE_SHIFT)
> +#define KFD_MMAP_TYPE_SHIFT	(62)
>   #define KFD_MMAP_TYPE_MASK	(0x3ULL << KFD_MMAP_TYPE_SHIFT)
>   #define KFD_MMAP_TYPE_DOORBELL	(0x3ULL << KFD_MMAP_TYPE_SHIFT)
>   #define KFD_MMAP_TYPE_EVENTS	(0x2ULL << KFD_MMAP_TYPE_SHIFT)
>   #define KFD_MMAP_TYPE_RESERVED_MEM	(0x1ULL << KFD_MMAP_TYPE_SHIFT)
>   #define KFD_MMAP_TYPE_MMIO	(0x0ULL << KFD_MMAP_TYPE_SHIFT)
>   
> -#define KFD_MMAP_GPU_ID_SHIFT (46 - PAGE_SHIFT)
> +#define KFD_MMAP_GPU_ID_SHIFT (46)
>   #define KFD_MMAP_GPU_ID_MASK (((1ULL << KFD_GPU_ID_HASH_WIDTH) - 1) \
>   				<< KFD_MMAP_GPU_ID_SHIFT)
>   #define KFD_MMAP_GPU_ID(gpu_id) ((((uint64_t)gpu_id) << KFD_MMAP_GPU_ID_SHIFT)\
>   				& KFD_MMAP_GPU_ID_MASK)
> -#define KFD_MMAP_GPU_ID_GET(offset)    ((offset & KFD_MMAP_GPU_ID_MASK) \
> +#define KFD_MMAP_GET_GPU_ID(offset)    ((offset & KFD_MMAP_GPU_ID_MASK) \
>   				>> KFD_MMAP_GPU_ID_SHIFT)
>   
> -#define KFD_MMAP_OFFSET_VALUE_MASK	(0x3FFFFFFFFFFFULL >> PAGE_SHIFT)
> -#define KFD_MMAP_OFFSET_VALUE_GET(offset) (offset & KFD_MMAP_OFFSET_VALUE_MASK)

This macro is still useful. See above. I think you should just update 
the mask and continue using it for clarity.

Regards,
   Felix


> -
>   /*
>    * When working with cp scheduler we should assign the HIQ manually or via
>    * the amdgpu driver to a fixed hqd slot, here are the fixed HIQ hqd slot
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> index 6abfb77ae540..39dc49b8fd85 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> @@ -554,8 +554,7 @@ static int kfd_process_init_cwsr_apu(struct kfd_process *p, struct file *filep)
>   		if (!dev->cwsr_enabled || qpd->cwsr_kaddr || qpd->cwsr_base)
>   			continue;
>   
> -		offset = (KFD_MMAP_TYPE_RESERVED_MEM | KFD_MMAP_GPU_ID(dev->id))
> -			<< PAGE_SHIFT;
> +		offset = KFD_MMAP_TYPE_RESERVED_MEM | KFD_MMAP_GPU_ID(dev->id);
>   		qpd->tba_addr = (int64_t)vm_mmap(filep, 0,
>   			KFD_CWSR_TBA_TMA_SIZE, PROT_READ | PROT_EXEC,
>   			MAP_SHARED, offset);