Re: [PATCH v6] drm/i915: return the correct usable aperture size under gvt environment

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On pe, 2017-05-26 at 09:37 +0800, Weinan Li wrote:
> I915_GEM_GET_APERTURE ioctl is used to probe aperture size from userspace.
> In gvt environment, each vm only use the ballooned part of aperture, so we
> should return the correct available aperture size exclude the reserved part
> by balloon.
> 
> v2: add 'reserved' in struct i915_address_space to record the reserved size
> in ggtt (Chris)
> 
> v3: remain aper_size as total, adjust aper_available_size exclude reserved
> and pinned. UMD driver need to adjust the max allocation size according to
> the available aperture size but not total size. KMD return the correct
> usable aperture size any time (Chris, Joonas)
> 
> v4: decrease reserved in deballoon (Joonas)
> 
> v5: add onion teardown in balloon, add vgt_deballoon_space (Joonas)
> 
> v6: change title name (Zhenyu)
> 
> Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
> Suggested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
> Signed-off-by: Weinan Li <weinan.z.li@intel.com>

<SNIP>

> @@ -156,8 +156,8 @@ int i915_mutex_lock_interruptible(struct drm_device *dev)
>  	mutex_unlock(&dev->struct_mutex);
>  
>  	args->aper_size = ggtt->base.total;
> -	args->aper_available_size = args->aper_size - pinned;
> -
> +	args->aper_available_size = args->aper_size -
> +		ggtt->base.reserved - pinned;

Wrong indentation here.

> +++ b/drivers/gpu/drm/i915/i915_vgpu.c
> @@ -92,6 +92,17 @@ struct _balloon_info_ {
>  
>  static struct _balloon_info_ bl_info;
>  
> +static void vgt_deballoon_space(struct i915_ggtt *ggtt,
> +			 struct drm_mm_node *node)

Ditto.

> +{
> +	DRM_INFO("deballoon space: range [ 0x%llx - 0x%llx ] %llu KiB.\n",
> +		 node->start, node->start + node->size, node->size / 1024);
> +
> +	ggtt->base.reserved -= node->size;
> +	drm_mm_remove_node(node);
> +	memset(node, 0, sizeof(*node));

memset() is not needed.

> @@ -127,9 +135,14 @@ static int vgt_balloon_space(struct i915_ggtt *ggtt,
>  
>  	DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
>  		 start, end, size / 1024);
> -	return i915_gem_gtt_reserve(&ggtt->base, node,
> +	ret = i915_gem_gtt_reserve(&ggtt->base, node,
>  				    size, start, I915_COLOR_UNEVICTABLE,
>  				    0);
> +	if (!ret)
> +		ggtt->base.reserved += size;
> +	else
> +		memset(node, 0, sizeof(*node));

memset() is not needed.

> +	return ret;
>  }
>  
>  /**
> @@ -215,14 +228,14 @@ int intel_vgt_balloon(struct drm_i915_private *dev_priv)
>  					ggtt->mappable_end, unmappable_base);
>  
>  		if (ret)
> -			goto err;
> +			goto err_out;

"err" is a good enough label for last level error path. "out" is used
when the path is also taken on a successful call of the function.

>  	}
>  
>  	if (unmappable_end < ggtt_end) {
>  		ret = vgt_balloon_space(ggtt, &bl_info.space[3],
>  					unmappable_end, ggtt_end);
>  		if (ret)
> -			goto err;
> +			goto err_deballoon_upon_mappable;

This function is about ballooning, so "deballoon" is bit verbose. Just
"err_upon_mappable".

I commented about the whitespace issues and memsets in previous
revisions already, so please go through the review comments
systematically to expedite further reviews.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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