[Intel-xe] [PATCH v2 28/31] drm/xe: Allow dma-fences as in-syncs for compute / faulting VM

[Rodrigo Vivi]

On Mon, May 01, 2023 at 05:17:24PM -0700, Matthew Brost wrote:
> This is allowed per the dma-fencing rules.

it would be good a word saying 'why' we are doing this.
only because we can it doesn't mean we should...

> 
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_sync.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_sync.c b/drivers/gpu/drm/xe/xe_sync.c
> index 99f1ed87196d..1e4e4acb2c4a 100644
> --- a/drivers/gpu/drm/xe/xe_sync.c
> +++ b/drivers/gpu/drm/xe/xe_sync.c
> @@ -105,6 +105,7 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>  {
>  	struct drm_xe_sync sync_in;
>  	int err;
> +	bool signal;
>  
>  	if (copy_from_user(&sync_in, sync_user, sizeof(*sync_user)))
>  		return -EFAULT;
> @@ -113,9 +114,10 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>  			 ~(SYNC_FLAGS_TYPE_MASK | DRM_XE_SYNC_SIGNAL)))
>  		return -EINVAL;
>  
> +	signal = sync_in.flags & DRM_XE_SYNC_SIGNAL;
>  	switch (sync_in.flags & SYNC_FLAGS_TYPE_MASK) {
>  	case DRM_XE_SYNC_SYNCOBJ:
> -		if (XE_IOCTL_ERR(xe, no_dma_fences))
> +		if (XE_IOCTL_ERR(xe, no_dma_fences && signal))
>  			return -ENOTSUPP;
>  
>  		if (XE_IOCTL_ERR(xe, upper_32_bits(sync_in.addr)))
> @@ -125,7 +127,7 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>  		if (XE_IOCTL_ERR(xe, !sync->syncobj))
>  			return -ENOENT;
>  
> -		if (!(sync_in.flags & DRM_XE_SYNC_SIGNAL)) {
> +		if (!signal) {
>  			sync->fence = drm_syncobj_fence_get(sync->syncobj);
>  			if (XE_IOCTL_ERR(xe, !sync->fence))
>  				return -EINVAL;
> @@ -133,7 +135,7 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>  		break;
>  
>  	case DRM_XE_SYNC_TIMELINE_SYNCOBJ:
> -		if (XE_IOCTL_ERR(xe, no_dma_fences))
> +		if (XE_IOCTL_ERR(xe, no_dma_fences && signal))
>  			return -ENOTSUPP;
>  
>  		if (XE_IOCTL_ERR(xe, upper_32_bits(sync_in.addr)))
> @@ -146,7 +148,7 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>  		if (XE_IOCTL_ERR(xe, !sync->syncobj))
>  			return -ENOENT;
>  
> -		if (sync_in.flags & DRM_XE_SYNC_SIGNAL) {
> +		if (signal) {
>  			sync->chain_fence = dma_fence_chain_alloc();
>  			if (!sync->chain_fence)
>  				return -ENOMEM;
> @@ -168,7 +170,7 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
>  		break;
>  
>  	case DRM_XE_SYNC_USER_FENCE:
> -		if (XE_IOCTL_ERR(xe, !(sync_in.flags & DRM_XE_SYNC_SIGNAL)))
> +		if (XE_IOCTL_ERR(xe, !signal))
>  			return -ENOTSUPP;
>  
>  		if (XE_IOCTL_ERR(xe, sync_in.addr & 0x7))
> -- 
> 2.34.1
>